Dynamic Link Exchange Protocol (DLEP)
draft-ietf-manet-dlep-06
The information below is for an old version of the document.
Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8175.
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Authors | Stan Ratliff , Bo Berry, Greg Harrison , Shawn Jury , Darryl Satterwhite | ||
Last updated | 2014-08-12 | ||
Replaces | draft-sratliff-manet-dlep | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-manet-dlep-06
Mobile Ad hoc Networks Working S. Ratliff Group B. Berry Internet-Draft G. Harrison Intended status: Standards Track S. Jury Expires: February 14, 2015 Cisco Systems D. Satterwhite Broadcom August 13, 2014 Dynamic Link Exchange Protocol (DLEP) draft-ietf-manet-dlep-06 Abstract When routing devices rely on modems to effect communications over wireless links, they need timely and accurate knowledge of the characteristics of the link (speed, state, etc.) in order to make forwarding decisions. In mobile or other environments where these characteristics change frequently, manual configurations or the inference of state through routing or transport protocols does not allow the router to make the best decisions. A bidirectional, event- driven communication channel between the router and the modem is necessary. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 14, 2014. Ratliff et al. Expires February 14, 2015 [Page 1] Internet-Draft DLEP August 2014 Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1 Requirements . . . . . . . . . . . . . . . . . . . . . . . 8 2. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3. Mandatory Versus Optional Items . . . . . . . . . . . . . . . . 9 4. Credits . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5. Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6. Extensions to DLEP . . . . . . . . . . . . . . . . . . . . . . 11 7. Normal Session Flow . . . . . . . . . . . . . . . . . . . . . 11 7.1 DLEP Router session flow - Discovery case . . . . . . . . . 11 7.2 DLEP Router session flow - Configured case . . . . . . . . . 12 7.3 DLEP Modem session flow . . . . . . . . . . . . . . . . . . 12 7.4 Common Session Flow . . . . . . . . . . . . . . . . . . . . 13 8. Mandatory Signals and Data Items . . . . . . . . . . . . . . . 14 9. Generic DLEP Signal Definition . . . . . . . . . . . . . . . . 15 10. DLEP Data Items . . . . . . . . . . . . . . . . . . . . . . . 16 10.1 DLEP Port . . . . . . . . . . . . . . . . . . . . . . . . 17 10.2 Peer Type . . . . . . . . . . . . . . . . . . . . . . . . 17 10.3 MAC Address . . . . . . . . . . . . . . . . . . . . . . . 18 10.4 IPv4 Address . . . . . . . . . . . . . . . . . . . . . . . 18 10.5 IPv6 Address . . . . . . . . . . . . . . . . . . . . . . . 19 10.6 Maximum Data Rate (Receive) . . . . . . . . . . . . . . . 20 10.7 Maximum Data Rate (Transmit) . . . . . . . . . . . . . . . 21 10.8 Current Data Rate (Receive) . . . . . . . . . . . . . . . 21 10.9 Current Data Rate (Transmit) . . . . . . . . . . . . . . . 22 10.10 Latency . . . . . . . . . . . . . . . . . . . . . . . . . 23 10.11 Resources (Receive) . . . . . . . . . . . . . . . . . . . 23 10.12 Resources (Transmit) . . . . . . . . . . . . . . . . . . 24 10.13 Relative Link Quality (Receive) . . . . . . . . . . . . . 25 10.14 Relative Link Quality (Transmit) . . . . . . . . . . . . 25 10.15 Status . . . . . . . . . . . . . . . . . . . . . . . . . 26 10.16 Heartbeat Interval . . . . . . . . . . . . . . . . . . . 26 Ratliff et al. Expires February 14, 2015 [Page 2] Internet-Draft DLEP August 2014 10.17 Link Characteristics ACK Timer . . . . . . . . . . . . . 27 10.18 Credit Window Status . . . . . . . . . . . . . . . . . . 28 10.19 Credit Grant Request . . . . . . . . . . . . . . . . . . 28 10.20 Credit Request . . . . . . . . . . . . . . . . . . . . . 29 10.22 DLEP Optional Signals Supported . . . . . . . . . . . . . 30 10.21 DLEP Optional Data Items Supported . . . . . . . . . . . 31 10.22 DLEP Vendor Extension . . . . . . . . . . . . . . . . . . 31 11. DLEP Protocol Signals . . . . . . . . . . . . . . . . . . . . 32 11.1 Signal TLV Values . . . . . . . . . . . . . . . . . . . . 32 11.2 Peer Discovery Signal . . . . . . . . . . . . . . . . . . . 33 11.3 Peer Offer Signal . . . . . . . . . . . . . . . . . . . . . 33 11.4 Peer Initialization Signal . . . . . . . . . . . . . . . . 34 11.5 Peer Initialization ACK Signal . . . . . . . . . . . . . . 34 11.6 Peer Update Signal . . . . . . . . . . . . . . . . . . . . 35 11.7 Peer Update ACK Signal . . . . . . . . . . . . . . . . . . 36 11.8 Peer Termination Signal . . . . . . . . . . . . . . . . . . 37 11.9 Peer Termination ACK Signal . . . . . . . . . . . . . . . . 37 11.10 Destination Up Signal . . . . . . . . . . . . . . . . . . 37 11.11 Destination Up ACK Signal . . . . . . . . . . . . . . . . 38 11.12 Destination Down Signal . . . . . . . . . . . . . . . . . 38 11.13 Destination Down ACK Signal . . . . . . . . . . . . . . . 39 11.14 Destination Update Signal . . . . . . . . . . . . . . . . 39 11.15 Heartbeat Signal . . . . . . . . . . . . . . . . . . . . . 40 11.16 Link Characteristics Request Signal . . . . . . . . . . . 40 11.17 Link Characteristics ACK Signal . . . . . . . . . . . . . 41 12. Security Considerations . . . . . . . . . . . . . . . . . . . 42 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 42 13.1 Registrations . . . . . . . . . . . . . . . . . . . . . . 42 13.2 Expert Review: Evaluation Guidelines . . . . . . . . . . . 42 13.3 Signal TLV Type Registration . . . . . . . . . . . . . . . 42 13.4 DLEP Data Item Registrations . . . . . . . . . . . . . . . 43 13.5 DLEP Well-known Port . . . . . . . . . . . . . . . . . . . 44 13.6 DLEP Multicast Address . . . . . . . . . . . . . . . . . . 44 14. Appendix A. . . . . . . . . . . . . . . . . . . . . . . . . . 44 14.1 Peer Level Signal Flows . . . . . . . . . . . . . . . . . 44 14.1.1 Modem Device Restarts Discovery . . . . . . . . . . . 44 14.1.2 Modem Device Detects Peer Offer Timeout . . . . . . . 44 14.1.3 Router Peer Offer Lost . . . . . . . . . . . . . . . . 46 14.1.4 Discovery Success . . . . . . . . . . . . . . . . . . 46 14.1.5 Router Detects a Heartbeat timeout . . . . . . . . . . 47 14.1.6 Modem Detects a Heartbeat timeout . . . . . . . . . . 47 14.1.7 Peer Terminate (from Modem) Lost . . . . . . . . . . . 48 14.1.8 Peer Terminate (from Router) Lost . . . . . . . . . . 48 14.2 Destination Specific Signal Flows . . . . . . . . . . . . 48 14.2.1 Modem Destination Up Lost . . . . . . . . . . . . . . 49 14.2.2 Router Detects Duplicate Destination Ups . . . . . . . 49 14.2.3 Destination Up, No Layer 3 Addresses . . . . . . . . . 50 14.2.4 Destination Up with IPv4, No IPv6 . . . . . . . . . . 50 Ratliff et al. Expires February 14, 2015 [Page 3] Internet-Draft DLEP August 2014 14.2.5 Destination Up with IPv4 and IPv6 . . . . . . . . . . 50 14.2.6 Destination Session Success . . . . . . . . . . . . . 51 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 51 Normative References . . . . . . . . . . . . . . . . . . . . . . . 52 Informative References . . . . . . . . . . . . . . . . . . . . . . 52 Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 52 1. Introduction There exist today a collection of modem devices that control links of variable datarate and quality. Examples of these types of links include line-of-sight (LOS) terrestrial radios, satellite terminals, and cable/DSL modems. Fluctuations in speed and quality of these links can occur due to configuration (in the case of cable/DSL modems), or on a moment-to-moment basis, due to physical phenomena like multipath interference, obstructions, rain fade, etc. It is also quite possible that link quality and datarate varies with respect to individual destinations on a link, and with the type of traffic being sent. As an example, consider the case of an 802.11g access point, serving 2 associated laptop computers. In this environment, the answer to the question "What is the datarate on the 802.11g link?" is "It depends on which associated laptop we're talking about, and on what kind of traffic is being sent." While the first laptop, being physically close to the access point, may have a datarate of 54Mbps for unicast traffic, the other laptop, being relatively far away, or obstructed by some object, can simultaneously have a datarate of only 32Mbps for unicast. However, for multicast traffic sent from the access point, all traffic is sent at the base transmission rate (which is configurable, but depending on the model of the access point, is usually 24Mbps or less). In addition to utilizing variable datarate links, mobile networks are challenged by the notion that link connectivity will come and go over time, without an effect on a router's interface state (Up or Down). Effectively utilizing a relatively short-lived connection is problematic in IP routed networks, as routing protocols tend to rely on interface state and independent timers at OSI Layer 3 to maintain network convergence (e.g. HELLO messages and/or recognition of DEAD routing adjacencies). These dynamic connections can be better utilized with an event-driven paradigm, where acquisition of a new neighbor (or loss of an existing one) is signaled, as opposed to a paradigm driven by timers and/or interface state. Another complicating factor for mobile networks are the different methods of physically connecting the modem devices to the router. Modems can be deployed as an interface card in a router's chassis, or as a standalone device connected to the router via Ethernet or serial link. In the case of Ethernet or serial attachment, with existing Ratliff et al. Expires February 14, 2015 [Page 4] Internet-Draft DLEP August 2014 protocols and techniques, routing software cannot be aware of convergence events occurring on the radio link (e.g. acquisition or loss of a potential routing neighbor), nor can the router be aware of the actual capacity of the link. This lack of awareness, along with the variability in datarate, leads to a situation where finding the (current) best route through the network to a given destination is difficult to establish and properly maintain. This is especially true of demand-based access schemes such as Demand Assigned Multiple Access (DAMA) implementations used on some satellite systems. With a DAMA-based system, additional datarate may be available, but will not be used unless the network devices emit traffic at rate higher than the currently established rate. Increasing the traffic rate does not guarantee additional datarate will be allocated; rather, it may result in data loss and additional retransmissions on the link. Addressing the challenges listed above, the authors have developed the Data Link Exchange Protocol, or DLEP. The DLEP protocol runs between a router and its attached modem devices, allowing the modem to communicate link characteristics as they change, and convergence events (acquisition and loss of potential routing destinations). The following diagrams are used to illustrate the scope of DLEP packets. |-------Local Node-------| |-------Remote Node------| | | | | +--------+ +-------+ +-------+ +--------+ | Router |=======| Modem |{~~~~~~~~}| Modem |=======| Router | | | | Device| | Device| | | +--------+ +-------+ +-------+ +--------+ | | | Link | | | |-DLEP--| | Protocol | |-DLEP--| | | | (e.g. | | | | | | 802.11) | | | Figure 1: DLEP Network In Figure 1, when the local modem detects the presence of a remote node, it (the local modem) sends a signal to its router via the DLEP protocol. Upon receipt of the signal, the local router may take whatever action it deems appropriate, such as initiating discovery protocols, and/or issuing HELLO messages to converge the network. On a continuing, as-needed basis, the modem devices utilize DLEP to report any characteristics of the link (datarate, latency, etc) that have changed. DLEP is independent of the link type and topology supported by the modem. Note that the DLEP protocol is specified to run only on the local link between router and modem. Some over the air signaling may be necessary between the local and remote modem in order to provide some parameters in DLEP signals between the local modem and local router, but DLEP does not specify how such over the Ratliff et al. Expires February 14, 2015 [Page 5] Internet-Draft DLEP August 2014 air signaling is carried out. Over the air signaling is purely a matter for the modem implementer. Figure 2 shows how DLEP can support a configuration where routers are connected with different link types. In this example, Modem A implements a point-to-point link, and Modem B is connected via a shared medium. In both cases, the DLEP protocol is used to report the characteristics of the link (datarate, latency, etc.) to routers. The modem is also able to use the DLEP session to notify the router when the remote node is lost, shortening the time required to re-converge the network. +--------+ +--------+ +----+ Modem A| | Modem A+---+ | | Device | <===== // ======> | Device | | | +--------+ P-2-P Link +--------+ | +---+----+ +---+----+ | Router | | Router | | | | | +---+----+ +---+----+ | +--------+ +--------+ | +-----+ Modem B| | Modem B| | | Device | o o o o o o o o | Device +--+ +--------+ o Shared o +--------+ o Medium o o o o o o o o +--------+ | Modem B| | Device | +---+----+ | | +---+----+ | Router | | | +--------+ Figure 2: DLEP Network with Multiple Modem Devices Ratliff et al. Expires February 14, 2015 [Page 6] Internet-Draft DLEP August 2014 DLEP defines a set of signals used by modems and their attached routers. The signals are used to communicate events that occur on the physical link(s) managed by the modem: for example, a remote node entering or leaving the network, or that the link has changed. Associated with these signals are a set of data items - information that describes the remote node (e.g., address information), and/or the characteristics of the link to the remote node. The protocol is defined as a collection of type-length-value (TLV) based formats, specifying the signals that are exchanged between a router and a modem, and the data items associated with the signal. This document specifies transport of DLEP signals and data items via the TCP transport, with a UDP-based discovery mechanism. Other transports for the protocol are possible, but are outside the scope of this document. DLEP signals are further defined as mandatory or optional. Signals will additionally have mandatory and optional data items. Implementations MUST support all mandatory signals and their mandatory data items to be considered compliant. Implementations MAY also support some, or all, of the optional signals and data items. DLEP uses a session-oriented paradigm between the modem device and its associated router. If multiple modem devices are attached to a router (as in Figure 2), a separate DLEP session MUST exist for each modem. If a modem device supports multiple connections to a router (via multiple logical or physical interfaces), or supports connections to multiple routers, a separate DLEP session MUST exist for each connection. This router/modem session provides a carrier for information exchange concerning "destinations" that are available via the modem device. A "destination" can be either physical (as in the case of a specific far-end router), or a logical destination (as in a Multicast group). As such, all of the destination-level exchanges in DLEP can be envisioned as building an information base concerning the remote nodes, and the link characteristics to those nodes. Any DLEP signal that is NOT understood by a receiver MUST result in an error indication being sent to the originator, and also MUST result in termination of the session between the DLEP peers. Any data item that is NOT understood by a receiver MUST be ignored. Multicast traffic destined for the variable-quality network (the network accessed via the DLEP modem) is handled in IP networks by deriving a Layer 2 MAC address based on the Layer 3 address. Leveraging on this scheme, Multicast traffic is supported in DLEP simply by treating the derived MAC address as any other "destination" (albeit a logical one) in the network. To support these logical destinations, one of the DLEP participants (typically, the router) Ratliff et al. Expires February 14, 2015 [Page 7] Internet-Draft DLEP August 2014 informs the other as to the existence of the logical neighbor. The modem, once it is aware of the existence of this logical neighbor, reports link characteristics just as it would for any other destination in the network. The specific algorithms a modem would use to report metrics on multicast (or logical) destinations is outside the scope of this specification, and is left to specific implementations to decide. 1.1 Requirements The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC 2119 [RFC2119]. 2. Assumptions Routers and modems that exist as part of the same node (e.g., that are locally connected) can utilize a discovery technique to locate each other, thus avoiding a-priori configuration. The router is responsible for initialing the discovery process, using the Peer Discovery signal. DLEP utilizes a session-oriented paradigm. A router and modem form a session by completing the discovery process. This router-modem session persists unless or until it either (1) times out, based on the timeout values supplied, or (2) is explicitly torn down by one of the participants. Note that while use of timers in DLEP is OPTIONAL, it is strongly recommended that implementations choose to run with timers enabled. DLEP assumes that participating modems, and their physical links, act as a transparent IEEE 802.1D bridge. Specifically, the assumption is that the destination MAC address for data traffic (frames destined for the far-end node, as opposed to the DLEP control traffic itself) in any frame emitted by the router should be the MAC address of a device in the remote node. DLEP also assumes that MAC addresses are unique within the context of the router-modem session. This document refers to a remote node as a "Destination". Destinations can be identified by either the router or the modem, and represent a specific destination (e.g., an address) that exists on the link(s) managed by the modem. A destination MUST contain a MAC address, it MAY optionally include a Layer 3 address (or addresses). Destinations MAY refer either to physical devices in the network, or to logical destinations, as in a derived multicast MAC address associated with a group. As "destinations" are discovered, DLEP routers and modems build an information base on destinations Ratliff et al. Expires February 14, 2015 [Page 8] Internet-Draft DLEP August 2014 accessible via the modem. Changes in link characteristics MAY then be reported as being "modem-wide" (effecting ALL destinations accessed via the modem) or MAY be neighbor (destination) specific. The DLEP signals concerning destinations thus become the way for routers and modems to maintain, and notify each other about, an information base representing the physical and logical (e.g., multicast) destinations accessible via the modem device. The information base would contain addressing information (e.g., MAC address, and OPTIONALLY, Layer 3 addresses), link characteristics (metrics), and OPTIONALLY, flow control information (credits). DLEP assumes that security on the session (e.g. authentication of session partners, encryption of traffic, or both) is dealt with by the underlying transport mechanism (e.g., by using a transport such as TLS [TLS]). This document specifies an implementation of the DLEP signals and data items running over the TCP transport. It is assumed that DLEP running over other transport mechanisms would be documented separately. 3. Mandatory Versus Optional Items As mentioned above, DLEP defines a core set of signals and data items as mandatory. Support for those signals and data items MUST exist in an implementation to guarantee interoperability and therefore make an implementation DLEP compliant. However, a mandatory signal or data item is not necessarily REQUIRED - as an example, consider the data item entitled "DLEP Optional Signals Supported", defined in section 10.22 of this document. The data item allows a DLEP implementation to list all optional behavior it supports, and is sent as a part of the Peer Initialization signal. Receiving implementations MUST be capable of parsing and understanding the optional signals that are offered. However, if the sending implementation has chosen NOT to implement ANY optional functionality, this data item would NOT be included in the Peer Initialization (e.g., absence of the mandatory data item would not be considered a protocol error, but as support for the core DLEP signals ONLY). Therefore, care should be taken to differentiate the notion of a mandatory data item versus one that is REQUIRED. 4. Credits DLEP includes an OPTIONAL credit-windowing scheme analogous to the one documented in [RFC5578]. In this scheme, traffic between the router and modem is treated as two unidirectional windows. This Ratliff et al. Expires February 14, 2015 [Page 9] Internet-Draft DLEP August 2014 document identifies these windows as the "Modem Receive Window", or MRW, and the "Router Receive Window", or RRW. If the OPTIONAL credit-windowing scheme is used, credits MUST be granted by the receiver on a given window - that is, on the "Modem Receive Window" (MRW), the modem is responsible for granting credits to the router, allowing it (the router) to send data to the modem. Likewise, the router is responsible for granting credits on the RRW, which allows the modem to send data to the router. DLEP expresses all credit data in number of octets. The total number of credits on a window, and the increment to add to a grant, are always expressed as a 64-bit unsigned quantity. If used, credits are managed on a neighbor-specific basis; that is, separate credit counts are maintained for each neighbor requiring the service. Credits do not apply to the DLEP session that exists between routers and modems. 5. Metrics DLEP includes the ability for the router and modem to communicate metrics that reflect the characteristics (e.g. datarate, latency) of the variable-quality link in use. DLEP does NOT specify how a given metric value is to be calculated, rather, the protocol assumes that metrics have been calculated with a "best effort", incorporating all pertinent data that is available to the modem device. As mentioned in the introduction section of this document, metrics have to be used within a context - for example, metrics to a unicast address in the network. DLEP allows for metrics to be sent within two contexts - metrics for a specific destination within the network (e.g., a specific router), and "modem-wide" (those that apply to all destinations accessed via the modem). Metrics are further subdivided into transmit and receive metrics. Metrics supplied on DLEP Peer signals are, by definition, modem-wide; metrics supplied on Destination signals are, by definition, used for the specific neighbor only. DLEP modem implementations MUST announce all supported metric items, and provide default values for those metrics, in the Peer Initialization signal. In order to introduce a new metric type, DLEP modem implementations MUST terminate the session with the router (via the Peer Terminate signal), and re-establish the session. It is left to implementations to choose sensible default values based on their specific characteristics. Modems having static (non- changing) link metric characteristics MAY report metrics only once Ratliff et al. Expires February 14, 2015 [Page 10] Internet-Draft DLEP August 2014 for a given neighbor (or once on a modem-wide basis, if all connections via the modem are of this static nature). The approach of allowing for different contexts for metric data increases both the flexibility and the complexity of using metric data. This document details the mechanism whereby the data is transmitted, however, the specific algorithms (precedence, etc) for utilizing the dual-context metrics is out of scope and not addressed by this document. 6. Extensions to DLEP While this draft represents the best efforts of the co-authors, and the working group, to be functionally complete, it is recognized that extensions to DLEP will in all likelihood be necessary as more link types are utilized. To allow for future innovation, the draft allocates numbering space for experimental implementations of both signals and data items. DLEP implementations MUST be capable of parsing and acting on the mandatory signals and data items as documented in this specification. DLEP signals/data items that are optional, or are in the experimental numbering range SHOULD be silently dropped by an implementation if they are not understood. The intent of the optional signals and data items, as well as the experimental numbering space, is to allow for further development of DLEP protocol features and function. Having experimental space reserved for both signals and data items gives maximum flexibility for extending the protocol as conditions warrant. For example, experimental data items could be used by implementations to send additional metrics. A combination of experimental signals, and associated data items, could be used to implement new flow control schemes. If subsequent research and development define new features and function, then it should be standardized either as an update to this document, or as an additional stand-alone specification. 7. Normal Session Flow Normal session flow is slightly different, depending on whether the implementation represents a modem or a router, and whether discovery techniques are used. The normal flow by DLEP partner type is: 7.1 DLEP Router session flow - Discovery case If the DLEP router implementation is utilizing the optional discovery mechanism, then the implementation will initialize a UDP socket, Ratliff et al. Expires February 14, 2015 [Page 11] Internet-Draft DLEP August 2014 binding it to an arbitrary port. This UDP socket is used to send the Peer Discovery signal to the DLEP link-local multicast address and port (TBD). The implementation then waits on receipt of a Peer Offer signal, which MUST contain the unicast address and port for TCP-based communication with a DLEP modem. The Peer Offer signal MAY contain multiple address/port combinations. If more than one address/port combination is in the Peer Offer, the DLEP router implementation SHOULD consider the list to be in priority sequence, with the "most desired" address/port combination listed first. However, router implementations MAY use their own heuristics to determine the best address/port combination. At this point, the router implementation MAY either destroy the UDP socket, or continue to issue Peer Discovery signals to the link-local address/port combination. In either case, the TCP session initialization occurs as in the configured case. 7.2 DLEP Router session flow - Configured case When a DLEP router implementation has the address and port information for a TCP connection to a modem (obtained either via configuration or via the discovery process described above), the router will initialize and bind a TCP socket. This socket is used to connect to the DLEP modem software. After a successful TCP connect, the modem implementation MUST issue a Peer Initialization signal to the DLEP router. The Peer Initialization signal MUST contain TLVs for ALL supported metrics from this modem (e.g. all MANDATORY metrics plus all OPTIONAL metrics supported by the implementation), along with the default values of those metrics. After sending the Peer Initialization, the modem implementation should wait for receipt of a Peer Initialization ACK signal from the router. Receipt of the Peer Initialization ACK indicates that the router has received and processed the Peer Initialization, and the session MUST transition to the "in session" state. At this point, signals regarding destinations in the network, and/or Peer Update signals, can flow on the DLEP session between modem and router. The "in session" state is maintained until one of the following conditions occur: o The session is explicitly terminated (using Peer Termination), or o The session times out, based on supplied timeout values. 7.3 DLEP Modem session flow DLEP modem implementations MUST support the discovery mechanism. Therefore, the normal flow is as follows: The implementation will initialize a UDP socket, binding that socket to the DLEP link-local multicast address (TBD) and the DLEP well- Ratliff et al. Expires February 14, 2015 [Page 12] Internet-Draft DLEP August 2014 known port number (also TBD). The implementation will then initialize a TCP socket, on a unicast address and port. This socket is used to listen for incoming TCP connection requests. When the modem implementation receives a Peer Discovery signal on the UDP socket, it responds by issuing a Peer Offer signal to the sender of the Peer Discovery. The Peer Offer signal MUST contain the unicast address and port of the TCP listen socket, described above. A DLEP modem implementation MAY respond with ALL address/port combinations that have an active TCP listen posted. If multiple address/port combinations are listed, the receiver of the Peer Offer MAY connect on any available address/port pair. Anything other than Peer Discovery signals received on the UDP socket MUST be silently dropped. When the DLEP modem implementation accepts a connection via TCP, it MUST send a Peer Initialization signal. The Peer Initialization MUST contain metric TLVs for ALL mandatory metrics, and MUST contain metric TLVs for ANY optional metrics supported by the modem. If a new metric is to be introduced, the DLEP session between router and modem MUST be terminated and restarted, and the new metric described in a Peer Initialization signal. 7.4 Common Session Flow In order to maintain the session between router and modem, periodic "Heartbeat" signals MAY be exchanged. These signals are intended to keep the session alive, and to verify bidirectional connectivity between the two participants. DLEP also provides an OPTIONAL Peer Update signal, intended to communicate some change in status (e.g., a change of layer 3 address parameters, or a modem-wide link change). In addition to the local (Peer level) signals above, the participants will transmit DLEP signals concerning destinations in the network. These signals trigger creation/maintenance/deletion of destinations in the information base of the recipient. For example, a modem will inform its attached router of the presence of a new destination via the "Destination Up" signal. Receipt of a Destination Up causes the router to allocate the necessary resources, creating an entry in the information base with the specifics (e.g., MAC Address, Latency, Data Rate, etc) of the neighbor. The loss of a destination is communicated via the "Destination Down" signal, and changes in status to the destination (e.g. varying link quality, or addressing changes) are communicated via the "Destination Update" signal. The information on a given neighbor will persist in the router's information base until (1) a "Destination Down" is received, indicating that the modem has lost contact with the remote node, or (2) the router/modem session Ratliff et al. Expires February 14, 2015 [Page 13] Internet-Draft DLEP August 2014 terminates, indicating that the router has lost contact with its own local modem. Again, metrics can be expressed within the context of a specific neighbor via the Destination Update signal, or on a modem-wide basis via the Peer Update signal. In cases where metrics are provided on the router/modem session, the receiver MUST propagate the metrics to all destinations in its information base that are accessed via the originator. A DLEP participant MAY send metrics both in a router/modem session context (via the Peer Update signal) and a specific neighbor context (via Destination Update) at any time. The heuristics for applying received metrics is left to implementations. In addition to receiving metrics about the link, DLEP provides an OPTIONAL signal allowing a router to request a different datarate, or latency, from the modem. This signal is referred to as the Link Characteristics Signal, and gives the router the ability to deal with requisite increases (or decreases) of allocated datarate/latency in demand-based schemes in a more deterministic manner. 8. Mandatory Signals and Data Items The following DLEP signals are considered core to the specification; implementations MUST support these signals, and the associated data items, in order to be considered compliant: Signal Data Items ====== ========== Peer Discovery (Router Only) None Peer Offer (Modem Only) IPv4 Address IPv6 address DLEP Port Peer Initialization Maximum Data Rate (Receive) Maximum Data Rate (Transmit) Current Data Rate (Receive) Current Data Rate (Transmit) Latency Relative Link Quality (Receive) Relative Link Quality (Transmit) DLEP Optional Signal Support DLEP Optional Data Item Support Peer Initialization ACK Status Peer Termination Status Ratliff et al. Expires February 14, 2015 [Page 14] Internet-Draft DLEP August 2014 Peer Termination ACK Status Destination Up MAC Address Maximum Data Rate (Receive) Maximum Data Rate (Transmit) Current Data Rate (Receive) Current Data Rate (Transmit) Latency Relative Link Quality (Receive) Relative Link Quality (Transmit) Destination Update MAC Address Maximum Data Rate (Receive) Maximum Data Rate (Transmit) Current Data Rate (Receive) Current Data Rate (Transmit) Latency Relative Link Quality (Receive) Relative Link Quality (Transmit) Destination Down MAC Address All other DLEP signals and data items are OPTIONAL. Implementations MAY choose to provide them. Implementations that do not support optional signals MUST report an error condition and terminate the router/modem session upon receipt of any such signal received. OPTIONAL data items received that are not supported MUST be silently dropped. 9. Generic DLEP Signal Definition The Generic DLEP Signal consists of a sequence of TLVs. The first TLV represents the signal being communicated (e.g., a "Destination Up", or a "Peer Offer"). Subsequent TLVs contain the data items pertinent to the signal (e.g., Maximum Data Rate, or Latency, etc). The Generic DLEP Packet Definition contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Signal TLV Type | Length | DLEP data items... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Signal - One of the DLEP Signal TLV type values defined in this document. Length - The length, expressed as a 16-bit Ratliff et al. Expires February 14, 2015 [Page 15] Internet-Draft DLEP August 2014 quantity, of all of the DLEP data items associated with this signal. DLEP data items - One or more data items, encoded in TLVs, as defined in this document. 10. DLEP Data Items As mentioned earlier, DLEP protocol signals are transported as a collection of TLVs. The first TLV present in a DLEP signal MUST be one of the Signal TLVs, documented in section 10. The signals are followed by one or more data items, indicating the specific changes that need to be instantiated in the receiver's information base. Valid DLEP Data Items are: TLV TLV Value Description ========================================= TBD DLEP Port TBD Peer Type TBD IPv4 Address TBD IPv6 Address TBD Maximum Data Rate (Receive) (MDRR) TBD Maximum Data Rate (Transmit) (MDRT) TBD Current Data Rate (Receive) (CDRR) TBD Current Data Rate (Transmit) (CDRT) TBD Latency TBD Receive Resources TBD Transmit Resources TBD Relative Link Quality (Receive) (RLQR) TBD Relative Link Quality (Transmit) (RLQT) TBD Status TBD Heartbeat Interval/Threshold TBD Neighbor down ACK timer TBD Link Characteristics ACK timer TBD Credit Window Status TBD Credit Grant TBD Credit Request TBD DLEP Optional Signals Supported TBD DLEP Optional Data Items Supported TBD DLEP Vendor Extension DLEP data item TLVs contain the following fields: 0 1 2 3 Ratliff et al. Expires February 14, 2015 [Page 16] Internet-Draft DLEP August 2014 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV Type | Length | Value... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - An 8-bit unsigned integer field specifying the data item being sent. Length - An 8-bit length of the value field of the data item Value - A field of length <Length> which contains data specific to a particular data item. 10.1 DLEP Port The DLEP Port TLV is a MANDATORY TLV in the Peer Offer signal. The DLEP Port TLV is used to indicate the TCP Port number on the DLEP server available for connections. The receiver MUST use this information to perform the TCP connect to the DLEP server. The DLEP Port TLV contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length=2 | TCP Port Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - Length is 2 TCP Port Number - TCP Port number on the DLEP server. 10.2 Peer Type The Peer Type TLV is an OPTIONAL TLV in both the Peer Discovery and Peer Offer signals. The Peer Type TLV is used by the router and modem to give additional information as to its type. The peer type is a string and is envisioned to be used for informational purposes (e.g. as output in a display command). The Peer Type TLV contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 Ratliff et al. Expires February 14, 2015 [Page 17] Internet-Draft DLEP August 2014 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length= peer |Peer Type String | | |type string len| | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - Length of peer type string. Peer Type String - Non-Null terminated string, using UTF-8 encoding. For example, a satellite modem might set this variable to 'Satellite terminal'. 10.3 MAC Address The MAC address TLV MUST appear in all destination-oriented signals (e.g. Destination Up, Destination Up ACK, Destination Down, Destination Down ACK, Destination Update, Link Characteristics Request, and Link Characteristics ACK). The MAC Address TLV contains the address of the destination on the remote node. The MAC address MAY be either a physical or a virtual destination. Examples of a virtual destination would be a multicast MAC address, or the broadcast MAC (0xFFFFFFFFFFFF). 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 6 | MAC Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MAC Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 6 MAC Address - MAC Address of the destination (either physical or virtual). 10.4 IPv4 Address The IPv4 Address TLV is an optional TLV. If supported, it MAY appear in Destination Up, Destination Update, Peer Initialization, and Peer Update signals. When included in Destination signals, the IPv4 Address TLV contains the IPv4 address of the destination, as well as a subnet mask value. In the Peer Update signal, it contains the IPv4 address of the originator of the signal. In either case, the TLV also Ratliff et al. Expires February 14, 2015 [Page 18] Internet-Draft DLEP August 2014 contains an indication of whether this is a new or existing address, or is a deletion of a previously known address. The IPv4 Address TLV contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 6 | Add/Drop | IPv4 Address | | | | Indicator | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 Address | Subnet Mask | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 6 Add/Drop - Value indicating whether this is a new or existing address (0x01), or a withdrawal of an address (0x02). IPv4 Address - The IPv4 address of the destination or peer. Subnet Mask - A subnet mask (0-32) to be applied to the IPv4 address. 10.5 IPv6 Address The IPv6 Address TLV is an optional TLV. If supported, it MAY be used in the Destination Up, Destination Update, Peer Initialization, and Peer Update Signals. When included in Destination signals, this data item contains the IPv6 address of the destination. In the Peer Discovery and Peer Update, it contains the IPv6 address of the originating peer. In either case, the data item also contains an indication of whether this is a new or existing address, or is a deletion of a previously known address, as well as a subnet mask. The IPv6 Address TLV contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 18 | Add/Drop | IPv6 Address | | | | Indicator | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Ratliff et al. Expires February 14, 2015 [Page 19] Internet-Draft DLEP August 2014 | IPv6 Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 Address | Subnet Mask | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 18 Add/Drop - Value indicating whether this is a new or existing address (0x01), or a withdrawal of an address (0x02). IPv6 Address - IPv6 Address of the destination or peer. Subnet Mask - A subnet mask value (0-128) to be applied to the Ipv6 address. 10.6 Maximum Data Rate (Receive) The Maximum Data Rate Receive (MDRR) TLV is a mandatory data item, used in Destination Up, Destination Update, Peer Initialization, Peer Update, and Link Characteristics ACK Signals to indicate the maximum theoretical data rate, in bits per second, that can be achieved while receiving data on the link. When metrics are reported via the signals listed above, the maximum data rate receive MUST be reported. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 8 | MDRR (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MDRR (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MDRR (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 8 Maximum Data Rate Receive - A 64-bit unsigned number, representing the maximum theoretical data rate, in bits per second (bps), that can be achieved while receiving on the link. Ratliff et al. Expires February 14, 2015 [Page 20] Internet-Draft DLEP August 2014 10.7 Maximum Data Rate (Transmit) The Maximum Data Rate Transmit (MDRT) TLV is a mandatory data item, used in Destination Up, Destination Update, Peer Initialization, Peer Update, and Link Characteristics ACK Signals to indicate the maximum theoretical data rate, in bits per second, that can be achieved while transmitting data on the link. When metrics are reported via the signals listed above, the maximum data rate transmit MUST be reported. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 8 | MDRT (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MDRT (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MDRT (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 8 Maximum Data Rate Transmit - A 64-bit unsigned number, representing the maximum theoretical data rate, in bits per second (bps), that can be achieved while transmitting on the link. 10.8 Current Data Rate (Receive) The Current Data Rate Receive (CDRR) TLV is a mandatory data item, used in Destination Up, Destination Update, Peer Initialization, Peer Update, Link Characteristics Request, and Link Characteristics ACK signals to indicate the rate at which the link is currently operating for receiving traffic. In the case of the Link Characteristics Request, CDRR represents the desired receive data rate for the link. When metrics are reported via the signals above (e.g. Destination Update), the current data rate receive MUST be reported. The Current Data Rate Receive TLV contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |TLV Flags=0x10 |Length = 8 |CDRR (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Ratliff et al. Expires February 14, 2015 [Page 21] Internet-Draft DLEP August 2014 | CDRR (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | CDRR (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 8 Current Data Rate Receive - A 64-bit unsigned number, representing the current data rate, in bits per second, that is currently be achieved while receiving traffic on the link. When used in the Link Characteristics Request, CDRR represents the desired receive rate, in bits per second, on the link. If there is no distinction between current and maximum receive data rates, current data rate receive SHOULD be set equal to the maximum data rate receive. 10.9 Current Data Rate (Transmit) The Current Data Rate Receive (CDRT) TLV is a mandatory data item, used in Destination Up, Destination Update, Peer Initialization, Peer Update, Link Characteristics Request, and Link Characteristics ACK signals to indicate the rate at which the link is currently operating for transmitting traffic. In the case of the Link Characteristics Request, CDRT represents the desired transmit data rate for the link. When metrics are reported via the signals above (e.g. Destination Update), the current data rate transmit MUST be reported. The Current Data Rate Transmit TLV contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |TLV Flags=0x10 |Length = 8 |CDRT (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | CDRT (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | CDRT (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 8 Ratliff et al. Expires February 14, 2015 [Page 22] Internet-Draft DLEP August 2014 Current Data Rate Transmit - A 64-bit unsigned number, representing the current data rate, in bits per second, that is currently be achieved while transmitting traffic on the link. When used in the Link Characteristics Request, CDRT represents the desired transmit rate, in bits per second, on the link. If there is no distinction between current and maximum transmit data rates, current data rate transmit MUST be set equal to the maximum data rate transmit. 10.10 Latency The Latency TLV is a mandatory data item. It is used in Peer Initialization, Destination Up, Destination Update, Peer Initialization, Peer Update, Link Characteristics Request, and Link Characteristics ACK signals to indicate the amount of latency on the link, or in the case of the Link Characteristics Request, to indicate the maximum latency required on the link. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 4 | Latency in microseconds | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Latency (Cont.) microsecs | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 4 Latency - A 32-bit unsigned value, representing the transmission delay that a packet encounters as it is transmitted over the link. In Destination Up, Destination Update, and Link Characteristics ACK, this value is reported as delay, in microseconds. The calculation of latency is implementation dependent. For example, the latency may be a running average calculated from the internal queuing. If a device cannot calculate latency, this TLV SHOUD NOT be issued. In the Link Characteristics Request Signal, this value represents the maximum delay, in microseconds, expected on the link. 10.11 Resources (Receive) Ratliff et al. Expires February 14, 2015 [Page 23] Internet-Draft DLEP August 2014 The Receive Resources TLV is an optional data item. If supported, it is used in Destination Up, Destination Update, Peer Initialization, Peer Update, and Link Characteristics ACK signals to indicate a percentage (0-100) amount of resources (e.g. battery power), committed to receiving data, remaining on the originating peer. The Resources TLV contains the following fields: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 1 | Rcv Resources| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 1 Receive Resources - A percentage, 0-100, representing the amount of remaining resources, such as battery power, allocated to receiving data. If a device cannot calculate receive resources, this TLV SHOULD NOT be issued. 10.12 Resources (Transmit) The Transmit Resources TLV is an optional data item. If supported, it is used in Destination Up, Destination Update, Peer Initialization, Peer Update, and Link Characteristics ACK signals to indicate a percentage (0-100) amount of resources (e.g. battery power), committed to transmitting data, remaining on the originating peer. The Resources TLV contains the following fields: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 1 | Xmt Resources| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 1 Transmit Resources - A percentage, 0-100, representing the amount of remaining resources, such as battery power, allocated to transmitting data. If the transmit resources cannot be calculated, then the TLV SHOULD Ratliff et al. Expires February 14, 2015 [Page 24] Internet-Draft DLEP August 2014 NOT be issued. 10.13 Relative Link Quality (Receive) The Relative Link Quality Receive (RLQR) TLV is an optional data item. If supported, it is used in Peer Initialization, Destination Up, Destination Update, Peer Initialization, Peer Update, and Link Characteristics ACK signals to indicate the quality of the link for receiving data as calculated by the originating peer. The Relative Link Quality (Receive) TLV contains the following fields: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 1 |RCV Rel. Link | | | |Quality (RLQR) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 1 Relative Link Quality (Receive) - A non-dimensional number, 1-100, representing relative link quality. A value of 100 represents a link of the highest quality. If a device cannot calculate the RLQR, this TLV SHOULD NOT be issued. 10.14 Relative Link Quality (Transmit) The Transmit Link Quality Receive (RLQT) TLV is an optional data item. It is used in Peer Initialization, Destination Up, Destination Update, Peer Initialization, Peer Update, and Link Characteristics ACK signals to indicate the quality of the link for transmitting data as calculated by the originating peer. The Relative Link Quality (Transmit) TLV contains the following fields: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 1 |XMT Rel. Link | Ratliff et al. Expires February 14, 2015 [Page 25] Internet-Draft DLEP August 2014 | | |Quality (RLQR) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 1 Relative Link Quality (Transmit) - A non-dimensional number, 1-100, representing relative link quality. A value of 100 represents a link of the highest quality. If a device cannot calculate the RLQT, this TLV SHOULD NOT be issued. 10.15 Status The Status TLV is sent as part of an acknowledgement signal, from either the modem or the router, to indicate the success or failure of a given request. The Status TLV contains the following fields: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 1 | Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 1 Termination Code - 0 = Success, Non-zero = Failure. Specific values of a non-zero termination code depend on the operation requested (e.g. Destination Up, Destination Down, etc). 10.16 Heartbeat Interval The Heartbeat Interval TLV is a mandatory TLV. It MUST be sent during Peer Initialization to indicate the desired Heartbeat timeout window. The receiver MUST either accept the timeout interval supplied by the sender, or reject the Peer Initialization, and close the socket. Implementations MUST implement heuristics such that DLEP signals sent/received reset the timer interval. The Interval is used to specify a period (in seconds) for Heartbeat Ratliff et al. Expires February 14, 2015 [Page 26] Internet-Draft DLEP August 2014 Signals (See Section 11.15). By specifying an Interval value of 0, implementations MAY indicates the desire to disable Heartbeat signals entirely (e.g., the Interval is set to an infinite value), however, it is strongly recommended that implementations use non 0 timer values. A DLEP session will be considered inactive, and MUST be torn down, by an implementation detecting that two (2) Heartbeat intervals have transpired without receipt of any DLEP signals. The Heartbeat Interval TLV contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 2 | Interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 2 Interval - 0 = Do NOT use heartbeats on this peer-to-peer session. Non-zero = Interval, in seconds, for heartbeat signals. 10.17 Link Characteristics ACK Timer The Link Characteristics ACK Timer TLV is an optional TLV. If supported, it MAY be sent during Peer Initialization to indicate the desired number of seconds to wait for a response to a Link Characteristics Request. If this TLV is omitted, implementations supporting the Link Characteristics Request SHOULD choose a default value. The Link Characteristics ACK Timer TLV contains the following fields: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 1 | Interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 1 Interval - 0 = Do NOT use timeouts for Link Characteristics Ratliff et al. Expires February 14, 2015 [Page 27] Internet-Draft DLEP August 2014 requests on this router/modem session. Non-zero = Interval, in seconds, to wait before considering a Link Characteristics Request has been lost. 10.18 Credit Window Status The Credit Window Status TLV is an optional TLV. If credits are supported by the DLEP participants (both the router and the modem), the Credit Window Status TLV MUST be sent by the participant receiving a Credit Grant Request for a given destination. The Credit Window Status TLV contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 16 | Modem Receive Window Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Modem Receive Window Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Modem Receive Window Value | Router Receive Window Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Router Receive Window Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Router Receive Window Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 16 Modem Receive Window Value - A 64-bit unsigned number, indicating the current (or initial) number of credits available on the Modem Receive Window. Router Receive Window Value - A 64-bit unsigned number, indicating the current (or initial) number of credits available on the Router Receive Window. 10.19 Credit Grant Request The Credit Grant Request TLV is an optional TLV. If credits are supported, the Credit Grant Request TLV is sent from a DLEP participant to grant an increment to credits on a window. The Credit Grant TLV is sent as a data item in either the Destination Up or Ratliff et al. Expires February 14, 2015 [Page 28] Internet-Draft DLEP August 2014 Destination Update signals. The value in a Credit Grant TLV represents an increment to be added to any existing credits available on the window. Upon successful receipt and processing of a Credit Grant TLV, the receiver MUST respond with a signal containing a Credit Window Status TLV to report the updated aggregate values for synchronization purposes. In the Destination Up signal, when credits are desired, the originating peer MUST set the initial credit value of the window it controls (e.g. the Modem Receive Window, or Router Receive Window) to an initial, non-zero value. If the receiver of a Destination Up signal with a Credit Grant Request TLV supports credits, the receiver MUST either reject the use of credits, via a Destination Up ACK response with the correct Status TLV, or set the initial value from the data contained in the Credit Window Status TLV. If the initialization completes successfully, the receiver MUST respond to the Destination Up signal with a Destination Up ACK signal that contains a Credit Window Status TLV, initializing its receive window. The Credit Grant TLV contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 8 | Credit Increment | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Credit Increment | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Credit Increment | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 8 Reserved - A 64-bit unsigned number representing the additional credits to be assigned to the credit window. Since credits can only be granted by the receiver on a window, the applicable credit window (either the MRW or the RRW) is derived from the sender of the grant. The Credit Increment MUST NOT cause the window to overflow; if this condition occurs, implementations MUST set the credit window to the maximum value contained in a 64-bit quantity. 10.20 Credit Request Ratliff et al. Expires February 14, 2015 [Page 29] Internet-Draft DLEP August 2014 The Credit Request TLV is an optional TLV. If credits are supported, the Credit Request TLV MAY be sent from either DLEP participant, via a Destination Update signal, to indicate the desire for the partner to grant additional credits in order for data transfer to proceed on the session. If the corresponding Destination Up signal for this session did NOT contain a Credit Window Status TLV, indicating that credits are to be used on the session, then the Credit Request TLV MUST be rejected by the receiver via a Destination Update ACK signal. The Credit Request TLV contains the following fields: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 1 | Reserved, MUST| | | | be set to 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 1 Reserved - This field is currently unused and MUST be set to 0. 10.22 DLEP Optional Signals Supported The DLEP Optional Signals Supported TLV is a mandatory data item. If optional signals (e.g., the Link Characteristics Request Signal) are supported, they MUST be enumerated with this data item inserted into the Peer Initialization and Peer Initialization ACK signals. Failure to indicate optional signals indicates to a receiving peer that the sending implementation ONLY supports the core (mandatory) items listed in this specification. Optional signals that are NOT enumerated in this data item when issuing Peer Initialization or Peer Initialization ACK MUST NOT be used during the DLEP session. The DLEP Optional Signals Supported TLV contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 2 + |List of optional signals ... | | |number of opt. | | | |signals. | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Ratliff et al. Expires February 14, 2015 [Page 30] Internet-Draft DLEP August 2014 Length - 2 + the number of optional signals supported List - An enumeration of the optional signal TLV Types supported by the implementation. 10.21 DLEP Optional Data Items Supported The DLEP Optional Data Items Supported TLV is a mandatory data item. If optional data items (e.g., Resources) are supported, they MUST be enumerated with this data item inserted into the Peer Initialization and Peer Initialization ACK signals. Failure to indicate optional data items indicates to a receiving peer that the sending implementation ONLY supports the core (mandatory) data items listed in this specification. Optional data items that are NOT listed in this data item MUST NOT be used during the DLEP session. The DLEP Optional Data Items Supported TLV contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 2 + |List of optional data items ...| | |number of opt. | | | |signals. | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 2 + the number of optional data items supported List - An enumeration of the optional data item TLV Types supported by the implementation. 10.22 DLEP Vendor Extension The DLEP Vendor Extension data item is an optional data item, and allows for vendor-defined information to be passed between DLEP participants. The precise data carried in the payload portion of the data item is vendor-specific, however, the payload MUST adhere to a Type-Length-Value format. This optional data item is ONLY valid on Peer Initialization ACK, and if present, SHOULD contain device- specific information geared to optimizing data transmission/reception over the modem's link. The DLEP Vendor Extension Data Item TLV contains the following fields: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 Ratliff et al. Expires February 14, 2015 [Page 31] Internet-Draft DLEP August 2014 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type = TBD | Length |OUI Length | Vendor OUI + | | | | | payload... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 3 + length of OUI (in octets) + payload length Vendor OUI - The vendor OUI, as specified in [IEEE] Payload - Vendor-specific payload, formatted as Type, Length, Value construct(s). 11. DLEP Protocol Signals DLEP signals are encoded as a string of Type-Length-Value (TLV) constructs. The first TLV in a DLEP signal MUST be a valid DLEP signal, as defined in section 11.1 of this document. Following the signal TLV is 0 or more TLVs, representing the data items that are appropriate for the signal. The layout of a DLEP signal is thus: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DLEP Signal |DLEP Signal length (3 + length |Start of DLEP | | Type value |of all data items) |data item TLVs | | (value TBD) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ All DLEP signals begin with this structure. Therefore, in the following descriptions of specific signals, this header structure is assumed, and will not be replicated. 11.1 Signal TLV Values As mentioned above, all DLEP signals begin with the Type value. Valid DLEP signals are: TLV TLV Value Description ========================================= TBD Peer Discovery TBD Peer Offer TBD Peer Initialization TBD Peer Update Ratliff et al. Expires February 14, 2015 [Page 32] Internet-Draft DLEP August 2014 TBD Peer Update ACK TBD Peer Termination TBD Peer Termination ACK TBD Destination Up TBD Destination Up ACK TBD Destination Down TBD Destination Down ACK TBD Destination Update TBD Heartbeat TBD Link Characteristics Request TBD Link Characteristics ACK 11.2 Peer Discovery Signal The Peer Discovery Signal is sent by a router to discover DLEP routers in the network. The Peer Offer signal is required to complete the discovery process. Implementations MAY implement their own retry heuristics in cases where it is determined the Peer Discovery Signal has timed out. Given the packet format described in section 11, the initial TLV Type value is set to DLEP_PEER_DISCOVERY (value TBD). There are NO Data Item TLVs associated with the Peer Discovery signal. 11.3 Peer Offer Signal The Peer Offer Signal is sent by a DLEP modem in response to a Peer Discovery Signal. Upon receipt, and processing, of a Peer Offer signal, the router responds by issuing a TCP connect to the address/port combination specified in the received Peer Offer. The Peer Offer signal MUST be sent to the unicast address of the originator of Peer Discovery. To construct a Peer Offer signal, the initial TLV type value is set to DLEP_PEER_OFFER (value TBD). The signal TLV is then followed by all MANDATORY Data Item TLVs, then by any OPTIONAL Data Item TLVs the implementation supports: Mandatory Data Item TLVs: - Heartbeat Interval - At least one (1) IPv4 or IPv6 Address TLV - DLEP Port Optional Data Item TLVs: - Peer Type Ratliff et al. Expires February 14, 2015 [Page 33] Internet-Draft DLEP August 2014 - Status 11.4 Peer Initialization Signal The Peer Initialization signal is sent by a router to start the DLEP TCP session. It is sent by the router after a TCP connect to an address/port combination that was obtained either via receipt of a Peer Offer, or from a-priori configuration. If any optional signals or data items are supported by the implementation, they MUST be enumerated in the DLEP Optional Signals Supported and DLEP Optional Data Items Supported items. Mandatory Data Item TLVs: - Heartbeat Interval - Optional Signals Supported - Optional Data Items Supported Optional Data Item TLVs: - Peer Type Note that optional signals and data items supported MUST be supplied with the Peer Initialization, so that the modem may determine what optional support is available within the router. If the Optional Signals Supported (or the Optional Data Items Supported) TLV is absent in Peer Initialization, the receiver of the signal MUST conclude that there is NO optional support in the sender. 11.5 Peer Initialization ACK Signal The Peer Initialization ACK signal is a mandatory signal, sent in response to a received Peer Initialization signal. The Peer Initialization ACK signal completes the TCP-level DLEP session establishment; the sender of the signal should transition to an "in- session" state when the signal is sent, and the receiver should transition to the "in-session" state upon receipt (and successful parsing) of Peer Initialization ACK. All supported metric data items MUST be included in the Peer Initialization ACK signal, with default values to be used on a "modem-wide" basis. This can be viewed as the modem "declaring" all supported metrics at DLEP session initialization. Receipt of any DLEP signal containing a metric data item NOT included in Peer Initialization ACK MUST be treated as an error, resulting in termination of the DLEP session between router and modem. If optional signals and/or data items are supported by the modem, they MUST be enumerated in the DLEP Optional Signals supported and DLEP Optional data items supported TLVs. The Peer Initialization ACK signal MAY contain the DLEP Vendor Extension data item, as documented in section 10.22 Ratliff et al. Expires February 14, 2015 [Page 34] Internet-Draft DLEP August 2014 After the Peer Initialization/Peer Initialization ACK signals have been successfully exchanged, implementations SHOULD only utilize options that are supported in BOTH peers (e.g. router and modem). Any attempt by a DLEP session peer to send an optional signal to a peer without support MUST result in an error which terminates the session. Any optional data item sent to a peer without support will be ignored and silently dropped. To construct a Peer Initialization ACK signal, the initial TLV type value is set to DLEP_PEER_INIT_ACK (value TBD). The signal TLV is then followed by the required data items: Mandatory Data Item TLVs: - Heartbeat Interval - Maximum Data Rate Receive - Maximum Data Rate Transmit - Current Data Rate Receive - Current Data Rate Transmit - Latency - Relative Link Quality Receive - Relative Link Quality Transmit - DLEP Optional Signals Supported - DLEP Optional Data Items Supported - Status Optional Data Item TLVs: - Peer Type - DLEP Vendor Extension 11.6 Peer Update Signal The Peer Update signal is an optional signal, sent by a DLEP peer to indicate local Layer 3 address changes, or for metric changes on a modem-wide basis. For example, addition of an IPv4 address to the router MAY prompt a Peer Update signal to its attached DLEP modems. Also, a modem that changes its Maximum Data Rate for all destinations MAY reflect that change via a Peer Update Signal to its attached router(s). Concerning Layer 3 addresses, if the modem is capable of understanding and forwarding this information (via proprietary mechanisms), the address update would prompt any remote DLEP modems (DLEP-enabled modems in a remote node) to issue a "Destination Update" signal to their local routers with the new (or deleted) addresses. Modems that do not track Layer 3 addresses SHOULD silently parse and ignore the Peer Update Signal. Modems that track Layer 3 addresses MUST acknowledge the Peer Update with a Peer Update ACK signal. Routers receiving a Peer Update with metric changes MUST apply the new metric to all destinations (remote nodes) accessible Ratliff et al. Expires February 14, 2015 [Page 35] Internet-Draft DLEP August 2014 via the modem. Supporting implementations are free to employ heuristics to retransmit Peer Update signals. The sending of Peer Update Signals for Layer 3 address changes SHOULD cease when a either participant (router or modem) determines that the other implementation does NOT support Layer 3 address tracking. If metrics are supplied with the Peer Update signal (e.g. Maximum Data Rate), these metrics are considered to be modem-wide, and therefore MUST be applied to all destinations in the information base associated with the router/modem session. To construct a Peer Update signal, the initial TLV type value is set to DLEP_PEER_UPDATE (value TBD). The Signal TLV is followed by any OPTIONAL Data Item TLVs. Optional Data Item TLVs: - IPv4 Address - IPv6 Address - Maximum Data Rate (Receive) - Maximum Data Rate (Transmit) - Current Data Rate (Receive) - Current Data Rate (Transmit) - Latency - Resources (Receive) - Resources (Transmit) - Relative Link Quality (Receive) - Relative Link Quality (Transmit) 11.7 Peer Update ACK Signal The Peer Update ACK signal is an optional signal, and is sent by implementations supporting Layer 3 address tracking and/or modem-wide metrics to indicate whether a Peer Update Signal was successfully processed. If the Peer Update ACK is issued, it MUST contain a Status data item, indicating the success or failure of processing the received Peer Update. To construct a Peer Update ACK signal, the initial TLV type value is set to DLEP_PEER_UPDATE_ACK (value TBD). The Status data item TLV is placed in the packet next, completing the Peer Update ACK. Mandatory Data Item TLVs: - Status Note that there are NO optional data item TLVs specified for this signal. Ratliff et al. Expires February 14, 2015 [Page 36] Internet-Draft DLEP August 2014 11.8 Peer Termination Signal The Peer Termination Signal is sent by a DLEP participant when the router/modem session needs to be terminated. Implementations receiving a Peer Termination signal MUST send a Peer Termination ACK signal to confirm the termination process. The sender of a Peer Termination signal is free to define its heuristics in event of a timeout. The receiver of a Peer Termination Signal MUST release all resources allocated for the router/modem session, and MUST eliminate all destinations in the information base accessible via the router/modem pair represented by the session. Router and modem state machines are returned to the "discovery" state. No Destination Down signals are sent. To construct a Peer Termination signal, the initial TLV type value is set to DLEP_PEER_TERMINATION (value TBD). The signal TLV is followed by any OPTIONAL Data Item TLVs the implementation supports: Optional Data Item TLVs: - Status 11.9 Peer Termination ACK Signal The Peer Termination Signal ACK is sent by a DLEP peer in response to a received Peer Termination order. Receipt of a Peer Termination ACK signal completes the teardown of the router/modem session. To construct a Peer Termination ACK signal, the initial TLV type value is set to DLEP_PEER_TERMINATION_ACK (value TBD). The Identification data item TLV is placed in the packet next, followed by any OPTIONAL TLVs the implementation supports: Optional Data Item TLVs: - Status 11.10 Destination Up Signal A DLEP participant sends the Destination Up signal to report that a new destination has been detected. A Destination Up ACK Signal is required to confirm a received Destination Up. A Destination Up signal can be sent either by the modem, to indicate that a new remote node has been detected, or by the router, to indicate the presence of a new logical destination (e.g., a Multicast group) exists in the network. The sender of the Destination Up Signal is free to define its retry Ratliff et al. Expires February 14, 2015 [Page 37] Internet-Draft DLEP August 2014 heuristics in event of a timeout. When a Destination Up signal is received and successfully parsed, the receiver should add knowledge of the new destination to its information base, indicating that the destination is accessible via the modem/router pair. To construct a Destination Up signal, the initial TLV type value is set to DLEP_DESTINATION_UP (value TBD). The MAC Address data item TLV is placed in the packet next, followed by any supported optional Data Item TLVs into the packet: Optional Data Item TLVs: - IPv4 Address - IPv6 Address - Maximum Data Rate (Receive) - Maximum Data Rate (Transmit) - Current Data Rate (Receive) - Current Data Rate (Transmit) - Latency - Resources (Receive) - Resources (Transmit) - Relative Link Factor (Receive) - Relative Link Factor (Transmit) - Credit Window Status 11.11 Destination Up ACK Signal A DLEP participant sends the Destination Up ACK Signal to indicate whether a Destination Up Signal was successfully processed. To construct a Destination Up ACK signal, the initial TLV type value is set to DLEP_DESTINATION_UP_ACK (value TBD). The MAC Address data item TLV is placed in the packet next, containing the MAC address of the DLEP destination. The implementation would then place any supported optional Data Item TLVs into the packet: Optional Data Item TLVs: - Credit Window Status 11.12 Destination Down Signal A DLEP peer sends the Destination Down signal to report when a destination (a remote node or a multicast group) is no longer reachable. The Destination Down signal MUST contain the MAC Address data item TLV. Other TLVs as listed are OPTIONAL, and MAY be present if an implementation supports them. A Destination Down ACK Signal MUST be sent by the recipient of a Destination Down signal to confirm that the relevant data has been removed from the information base. Ratliff et al. Expires February 14, 2015 [Page 38] Internet-Draft DLEP August 2014 The sender of the Destination Down signal is free to define its retry heuristics in event of a timeout. To construct a Destination Down signal, the initial TLV type value is set to DLEP_DESTINATION_DOWN (value TBD). The signal TLV is followed by the mandatory MAC Address data item TLV. Note that there are NO OPTIONAL data item TLVs for this signal. 11.13 Destination Down ACK Signal A DLEP participant sends the Destination Down ACK Signal to indicate whether a received Destination Down Signal was successfully processed. If successfully processed, the sender of the ACK MUST have removed all entries in the information base that pertain to the referenced destination. As with the Destination Down signal, there are NO OPTIONAL Data Item TLVs defined for the Destination Down ACK signal. To construct a Destination Down signal, the initial TLV type value is set to DLEP_DESTINATION_DOWN_ACK (value TBD). The mandatory data item TLVs follow: - MAC Address Data item - Status data item 11.14 Destination Update Signal A DLEP participant sends the Destination Update signal when it detects some change in the information base for a given destination (remote node or multicast group). Some examples of changes that would prompt a Destination Update signal are: - Change in link metrics (e.g., Data Rates) - Layer 3 addressing change (for implementations that support it) To construct a Destination Update signal, the initial TLV type value is set to DLEP_DESTINATION_UPDATE (value TBD). Following the signal TLV are the mandatory Data Item TLVs: MAC Address data item TLV After placing the mandatory data item TLV into the packet, the implementation would place any supported OPTIONAL data item TLVs. Possible OPTIONAL data item TLVs are: Ratliff et al. Expires February 14, 2015 [Page 39] Internet-Draft DLEP August 2014 - IPv4 Address - IPv6 Address - Maximum Data Rate (Receive) - Maximum Data Rate (Transmit) - Current Data Rate (Receive) - Current Data Rate (Transmit) - Latency - Resources (Receive) - Resources (Transmit) - Relative Link Quality (Receive) - Relative Link Quality (Transmit) - Credit Window Status - Credit Grant - Credit Request 11.15 Heartbeat Signal A Heartbeat Signal is sent by a DLEP participant every N seconds, where N is defined in the "Heartbeat Interval" field of the Peer Initialization signal. Note that implementations setting the Heartbeat Interval to 0 effectively set the interval to an infinite value, therefore, in those cases, this signal would NOT be sent. The signal is used by participants to detect when a DLEP session partner (either the modem or the router) is no longer communicating. Participants SHOULD allow two (2) heartbeat intervals to expire with no traffic on the router/modem session before initiating DLEP session termination procedures. To construct a Heartbeat signal, the initial TLV type value is set to DLEP_PEER_HEARTBEAT (value TBD). The signal TLV is followed by the mandatory Heartbeat Interval/Threshold data item. Note that there are NO OPTIONAL data item TLVs for this signal. 11.16 Link Characteristics Request Signal The Link Characteristics Request Signal is an optional signal, and is sent by the router to request that the modem initiate changes for specific characteristics of the link. The request can reference either a real (e.g., a remote node), or a logical (e.g., a multicast group) destination within the network. The Link Characteristics Request signal contains either a Current Data Rate (CDRR or CDRT) TLV to request a different datarate than what is currently allocated, a Latency TLV to request that traffic delay on the link not exceed the specified value, or both. A Link Ratliff et al. Expires February 14, 2015 [Page 40] Internet-Draft DLEP August 2014 Characteristics ACK Signal is required to complete the request. Implementations are free to define their retry heuristics in event of a timeout. Issuing a Link Characteristics Request with ONLY the MAC Address TLV is a mechanism a peer MAY use to request metrics (via the Link Characteristics ACK) from its partner. To construct a Link Characteristics Request signal, the initial TLV type value is set to DLEP_Destination_LINK_CHAR_REQ (value TBD). Following the signal TLV is the mandatory Data Item TLV: MAC Address data item TLV After placing the mandatory data item TLV into the packet, the implementation would place any supported OPTIONAL data item TLVs. Possible optional data item TLVs are: Current Data Rate - If present, this value represents the NEW (or unchanged, if the request is denied) Current Data Rate in bits per second (bps). Latency - If present, this value represents the maximum desired latency (e.g., it is a not-to-exceed value) in microseconds on the link. 11.17 Link Characteristics ACK Signal The LInk Characteristics ACK signal is an optional signal, and is sent by modems supporting it to the router letting the router know the success or failure of a requested change in link characteristics. The Link Characteristics ACK signal SHOULD contain a complete set of metric data item TLVs. It MUST contain the same TLV types as the request. The values in the metric data item TLVs in the Link Characteristics ACK signal MUST reflect the link characteristics after the request has been processed. To construct a Link Characteristics Request ACK signal, the initial TLV type value is set to DLEP_Destination_LINK_CHAR_ACK (value TBD). Following the signal TLV is the mandatory Data Item TLV: MAC Address data item TLV After placing the mandatory data item TLV into the packet, the implementation would place any supported OPTIONAL data item TLVs. Possible OPTIONAL data item TLVs are: Current Data Rate - If present, this value represents the requested data rate in bits per second (bps). Ratliff et al. Expires February 14, 2015 [Page 41] Internet-Draft DLEP August 2014 Latency - If present, this value represents the NEW maximum latency (or unchanged, if the request is denied), expressed in microseconds, on the link. 12. Security Considerations The protocol does not contain any mechanisms for security (e.g. authentication or encryption). The protocol assumes that any security would be implemented in the underlying transport (for example, by use of DTLS or some other mechanism), and is therefore outside the scope of this document. 13. IANA Considerations This section specifies requests to IANA. 13.1 Registrations This specification defines: o A new repository for DLEP signals, with fifteen values currently assigned. o Reservation of numbering space for Experimental DLEP signals. o A new repository for DLEP Data Items, with twenty-one values currently assigned. o Reservation of numbering space in the Data Items repository for experimental data items. o A request for allocation of a well-known port for DLEP communication. o A request for allocation of a multicast address for DLEP discovery. 13.2 Expert Review: Evaluation Guidelines No additional guidelines for expert review are anticipated. 13.3 Signal TLV Type Registration A new repository must be created with the values of the DLEP signals. Ratliff et al. Expires February 14, 2015 [Page 42] Internet-Draft DLEP August 2014 Valid signals are: o Peer Discovery o Peer Offer o Peer Initialization o Peer Initialization ACK o Peer Update o Peer Update ACK o Peer Termination o Peer Termination ACK o Destination Up o Destination Up ACK o Destination Down o Destination Down ACK o Destination Update o Heartbeat o Link Characteristics Request o Link Characteristics ACK It is also requested that the repository contain space for experimental signal types. 13.4 DLEP Data Item Registrations A new repository for DLEP Data Items must be created. Valid Data Items are: o Peer Type o MAC Address o IPv4 Address o IPv6 Address o Maximum Data Rate (Receive) o Maximum Data Rate (Transmit) o Current Data Rate (Receive) o Current Data Rate (Transmit) o Latency o Resources (Receive) o Resources (Transmit) o Relative Link Quality (Receive) o Relative Link Quality (Transmit) o Status o Heartbeat Interval/Threshold o Link Characteristics ACK Timer o Credit Window Status o Credit Grant o Credit Request o DLEP Optional Signals Supported Ratliff et al. Expires February 14, 2015 [Page 43] Internet-Draft DLEP August 2014 o DLEP Optional Data Items Supported o DLEP Vendor Extension It is also requested that the registry allocation contain space for experimental data items. 13.5 DLEP Well-known Port It is requested that IANA allocate a well-known port number for DLEP communication. 13.6 DLEP Multicast Address It is requested that IANA allocate a multicast address for DLEP discovery signals. 14. Appendix A. 14.1 Peer Level Signal Flows 14.1.1 Modem Device Restarts Discovery Router Modem Signal Description ==================================================================== <-------Peer Discovery--------- Modem initiates discovery ---------Peer Offer-----------> Router detects a problem, sends w/ Non-zero Status TLV Peer Offer w/Status TLV indicating the error. Modem accepts failure, restarts discovery process. <-------Peer Discovery--------- Modem initiates discovery ---------Peer Offer-----------> Router accepts, sends Peer Offer w/ Zero Status TLV w/ Status TLV indicating success. Discovery completed. 14.1.2 Modem Device Detects Peer Offer Timeout Ratliff et al. Expires February 14, 2015 [Page 44] Internet-Draft DLEP August 2014 Router Modem Signal Description ==================================================================== <-------Peer Discovery--------- Modem initiates discovery, starts a guard timer. Modem guard timer expires. Modem restarts discovery process. <-------Peer Discovery--------- Modem initiates discovery, starts a guard timer. ---------Peer Offer-----------> Router accepts, sends Peer Offer w/ Zero Status TLV w/ Status TLV indicating success. Discovery completed. Ratliff et al. Expires February 14, 2015 [Page 45] Internet-Draft DLEP August 2014 14.1.3 Router Peer Offer Lost Router Modem Signal Description ==================================================================== <-------Peer Discovery--------- Modem initiates discovery, starts a guard timer. ---------Peer Offer-------|| Router offers availability Modem times out on Peer Offer, restarts discovery process. <-------Peer Discovery--------- Modem initiates discovery ---------Peer Offer-----------> Router detects subsequent discovery, internally terminates the previous, accepts the new association, sends Peer Offer w/Status TLV indicating success. Discovery completed. 14.1.4 Discovery Success Router Modem Signal Description ==================================================================== <-------Peer Discovery--------- Modem initiates discovery ---------Peer Offer-----------> Router offers availability <-----Peer Initialization------ Modem Connects on TCP Port <------Peer Heartbeat---------- -------Peer Heartbeat---------> <==============================> Signal flow about destinations (i.e. Destination Up, Destination Down, Destination update) <-------Peer Heartbeat--------- -------Peer Heartbeat---------> Ratliff et al. Expires February 14, 2015 [Page 46] Internet-Draft DLEP August 2014 --------Peer Term Req---------> Terminate Request <--------Peer Term Res--------- Terminate Response 14.1.5 Router Detects a Heartbeat timeout Router Modem Signal Description ==================================================================== <-------Peer Heartbeat--------- -------Peer Heartbeat---------> ||---Peer Heartbeat--------- ~ ~ ~ ~ ~ ~ ~ -------Peer Heartbeat---------> ||---Peer Heartbeat--------- Router Heartbeat Timer expires, detects missing heartbeats. Router takes down all destination sessions and terminates the Peer association. ------Peer Terminate ---------> Peer Terminate Request Modem takes down all destination sessions, then acknowledges the Peer Terminate <----Peer Terminate ACK--------- Peer Terminate ACK 14.1.6 Modem Detects a Heartbeat timeout Router Modem Signal Description ==================================================================== <-------Peer Heartbeat--------- -------Peer Heartbeat------|| <-------Peer Heartbeat--------- ~ ~ ~ ~ ~ ~ ~ -------Peer Heartbeat------|| Ratliff et al. Expires February 14, 2015 [Page 47] Internet-Draft DLEP August 2014 <-------Peer Heartbeat--------- Modem Heartbeat Timer expires, detects missing heartbeats. Modem takes down all destination sessions <-------Peer Terminate-------- Peer Terminate Request Router takes down all destination sessions, then acknowledges the Peer Terminate ------Peer Terminate ACK-----> Peer Terminate ACK 14.1.7 Peer Terminate (from Modem) Lost Router Modem Signal Description ==================================================================== ||------Peer Terminate-------- Modem Peer Terminate Request Router Heartbeat times out, terminates association. --------Peer Terminate-------> Router Peer Terminate <-----Peer Terminate ACK------ Modem sends Peer Terminate ACK 14.1.8 Peer Terminate (from Router) Lost Router Modem Signal Description ==================================================================== -------Peer Terminate--------> Router Peer Terminate Request Modem HB times out, terminates association. <------Peer Terminate-------- Modem Peer Terminate ------Peer Terminate ACK-----> Peer Terminate ACK 14.2 Destination Specific Signal Flows Ratliff et al. Expires February 14, 2015 [Page 48] Internet-Draft DLEP August 2014 14.2.1 Modem Destination Up Lost Router Modem Signal Description ==================================================================== ||-----Destination Up ------------ Modem sends Destination Up Modem timesout on ACK <------Destination Up ------------ Modem sends Destination Up ------Destination Up ACK---------> Router accepts the destination session <------Destination Update--------- Modem Destination Metrics . . . . . . . . <------Destination Update--------- Modem Destination Metrics 14.2.2 Router Detects Duplicate Destination Ups Router Modem Signal Description ==================================================================== <------Destination Up ------------ Modem sends Destination Up ------Destination Up ACK-------|| Router accepts the destination session Modem timesout on ACK <------Destination Up ------------ Modem resends Destination Up Router detects duplicate Destination, takes down the previous, accepts the new Destination. ------Destination Up ACK---------> Router accepts the destination session <------Destination Update--------- Modem Destination Metrics . . . . . . . . <------Destination Update--------- Modem Destination Metrics Ratliff et al. Expires February 14, 2015 [Page 49] Internet-Draft DLEP August 2014 14.2.3 Destination Up, No Layer 3 Addresses Router Modem Signal Description ==================================================================== <------Destination Up ------------ Modem sends Destination Up ------Destination Up ACK---------> Router accepts the destination session Router ARPs for IPv4 if defined. Router drives ND for IPv6 if defined. <------Destination Update--------- Modem Destination Metrics . . . . . . . . <------Destination Update--------- Modem Destination Metrics 14.2.4 Destination Up with IPv4, No IPv6 Router Modem Signal Description ==================================================================== <------Destination Up ------------ Modem sends Destination Up with the IPv4 TLV ------Destination Up ACK---------> Router accepts the destination session Router drives ND for IPv6 if defined. <------Destination Update--------- Modem Destination Metrics . . . . . . . . <------Destination Update--------- Modem Destination Metrics 14.2.5 Destination Up with IPv4 and IPv6 Router Modem Signal Description ==================================================================== <------Destination Up ------------ Modem sends Destination Up with the IPv4 and IPv6 TLVs ------Destination Up ACK---------> Router accepts the destination session Ratliff et al. Expires February 14, 2015 [Page 50] Internet-Draft DLEP August 2014 <------Destination Update--------- Modem Destination Metrics . . . . . . . . 14.2.6 Destination Session Success Router Modem Signal Description ==================================================================== ---------Peer Offer-----------> Router offers availability -------Peer Heartbeat---------> <------Destination Up ----------- Modem ------Destination Up ACK--------> Router <------Destination Update--------- Modem . . . . . . . . <------Destination Update--------- Modem Modem initiates the terminate <------Destination Down ---------- Modem ------Destination Down ACK-------> Router or Router initiates the terminate ------Destination Down ----------> Router <------Destination Down ACK------- Modem Acknowledgements The authors would like to acknowledge and thank the members of the DLEP design team, who have provided invaluable insight. The members of the design team are: Teco Boot, Bow-Nan Cheng, John Dowdell, Henning Rogge, and Rick Taylor. The authors would also like to acknowledge the influence and contributions of Chris Olsen, Martin Duke, Subir Das, Jaewon Kang, Vikram Kaul, and Nelson Powell. Ratliff et al. Expires February 14, 2015 [Page 51] Internet-Draft DLEP August 2014 Normative References [RFC5578] Berry, B., Ed., "PPPoE with Credit Flow and Metrics", RFC 5578, February 2010. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [IEEE] http://standards.ieee.org/develop/regauth/oui/index.html Informative References [TLS] Dierks, T. and Rescorla, E. "The Transport Layer Security (TLS) Protocol", RFC 5246, August 2008. Author's Addresses Stan Ratliff Cisco 170 West Tasman Drive San Jose, CA 95134 USA EMail: sratliff@cisco.com Bo Berry Cisco 170 West Tasman Drive San Jose, CA 95134 USA EMail: Greg Harrison Cisco 170 West Tasman Drive San Jose, CA 95134 USA EMail: greharri@cisco.com Shawn Jury Cisco 170 West Tasman Drive San Jose, CA 95134 USA Email: sjury@cisco.com Darryl Satterwhite Broadcom USA Ratliff et al. Expires February 14, 2015 [Page 52] Internet-Draft DLEP August 2014 Email: dsatterw@broadcom.com Ratliff et al. Expires February 14, 2015 [Page 53]