Network Working Group C. Jacquenet Internet Draft France Telecom Document: draft-jacquenet-cops-te-00.txt February 2004 Category: Experimental Expires August 2004 A COPS Client-Type for Traffic Engineering <draft-jacquenet-cops-te-00.txt> Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC 2026 [1]. 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. Abstract This draft specifies a COPS (Common Open Policy Service) client-type designed for the enforcement of IP Routing and Traffic Engineering (TE) policies. The usage of this TE COPS client-type relies upon the activation of the COPS protocol for policy provisioning purposes. Table of Contents 1. Introduction...............................................2 2. Conventions used in this Document..........................3 3. Terminology Considerations.................................3 4. The Generic Model of an IP Routing/TE Policy Enforcement Scheme.......................................4 5. TE Client-Type Specific Information to be Carried in COPS Messages............................................6 5.1. Client-Type Field of the Common Header of Every COPS Message..................................................7 5.2. COPS Message Content.......................................7 5.2.1. Request Messages (REQ).....................................7 5.2.2. Decision Messages (DEC)....................................8 Jacquenet Experimental - Expires August 2004 [Page 1]
Internet Draft COPS Usage for Traffic Engineering February 2004 5.2.3. Report Messages (RPT)......................................8 5.3. Backward Compatibility Issues..............................9 6. COPS-PR Usage of the TE Client-Type.......................10 7. IANA Considerations.......................................11 8. Security Considerations...................................11 9. References................................................11 10. Acknowledgments...........................................12 11. Author's Address..........................................12 12. Full Copyright Statement..................................13 1. Introduction The deployment of value-added IP services over the Internet has become one of the most competing challenges for service providers, as well as a complex technical issue, from a (dynamic) resource provisioning perspective. To address such technical issue, the COPS protocol ([2]) and its usage for the support of Policy Provisioning ([3]) is one of the specification efforts of the Resource Allocation Protocol (rap) Working Group of the IETF that should help service providers by introducing a high level of automation for the dynamic production of a wide range of services and policies. Such policies include routing and traffic engineering policies. They aim at appropriately provisioning, allocating/de-allocating, and using the switching and the transmission resources of an IP network (i.e. the routers and the links that connect these routers, respectively), according to a set of constraints like Quality of Service (QoS) requirements (e.g. rate, one-way delay, inter-packet delay variation, etc.) that have been possibly negotiated between the customers and the service providers, as well as routing metrics, which can reflect the network conditions. Within the scope of this document, the actual enforcement of IP routing and traffic engineering policies is primarily based upon the activation of both intra- and inter-domain routing protocols (e.g. [4], [5], not to mention the use of multicast routing protocols [6]) that will be activated in the network to appropriately select, install, maintain and possibly withdraw routes that will comply with the aforementioned QoS requirements and/or specific routing constraints, depending on the type of traffic that will be conveyed along these routes. It is therefore necessary to provide the route selection processes with the information that will depict the routing policies that are to be enforced within a domain, including the aforementioned constraints and metrics, given the dynamic routing protocols actually support traffic engineering capabilities for the calculation and the selection of such routes. Jacquenet Experimental - Expires August 2004 [Page 2]
Internet Draft COPS Usage for Traffic Engineering February 2004 These capabilities are currently being specified in [7] and [8] for the OSPF (Open Shortest Path First) and the IS-IS (Intermediate System to Intermediate System routing protocol, [9]) interior routing protocols respectively, while there is an equivalent specification effort for the BGP4 (Border Gateway Protocol, version 4) protocol, as described in [10], for example. To provide the routers that will participate in the dynamic enforcement of an IP routing and/or traffic engineering policy with the appropriate configuration information (such as metrics' values), one possibility is to use the COPS protocol and its usage for policy provisioning. To do so, a new COPS client-type is specified, called the "Traffic Engineering" client-type, and this specification effort is the purpose of this draft. This document is organized into the following sections: - Section 3 introduces terminology as well as basic assumptions, - Section 4 introduces the generic architecture, - Section 5 defines the contents of the COPS messages that MUST include the TE client-type specific information, - Section 6 defines the usage of the TE client-type, including its mode of operation with the PDP (Policy Decision Point, [11]) with whom a COPS communication has been established, - Finally, sections 7 and 8 introduce IANA and some security considerations, respectively. 2. Conventions used in this Document 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 RFC 2119 [12]. 3. Terminology Considerations The enforcement of an IP routing/TE policy is based upon the processing of configuration information that reflects the characteristics of these policies (IGP metric values, BGP attributes' values, QoS requirements and/or constraints, etc.). This information is called the "QoS-related" information within the context of this draft. Then, this QoS-related information must be taken into account by the routing processes that will participate in the calculation, the selection, the installation and the maintenance of the routes that will comply with the aforementioned requirements. The algorithms invoked by the routing processes take into account the cost metrics (whose corresponding values can possibly be inferred by a DSCP (DiffServ Code Point, [13]) value) that have been assigned by the network administrators. Jacquenet Experimental - Expires August 2004 [Page 3]
Internet Draft COPS Usage for Traffic Engineering February 2004 This metric-related information is called the "TE"-related information within the context of this draft. Thus, this draft makes a distinction between QoS-related information and TE-related information, where: - QoS-related information is negotiated between customers and service providers, - TE-related configuration information is dynamically provided to routers, and is exchanged between routers so that they can compute, select, install, and maintain the (traffic-engineered) routes accordingly. From this perspective, QoS-related information provides information on the traffic (both unicast and multicast) to be forwarded in the network (such as source address, destination address, protocol identification, DSCP marking, etc.), whereas TE-related information provides information for the routing processes that will indicate the routers of the network how to forward the aforementioned traffic, i.e. compute and select the routes that will convey such traffic. Given these basic assumptions, this draft aims at specifying a COPS- based TE client-type that has the following characteristics: - The TE client-type is supported by the PEP (Policy Enforcement Point) capability that allows a router to enforce a collection of policies, thanks to a COPS communication that has been established between the PEP and the PDP, - The actual enforcement of an IP routing/TE policy is based upon the TE-related configuration information that will be exchanged between the PDP and the PEP, and that will be used by the router for selecting, installing, maintaining and possibly withdrawing IP TE routes. 4. The Generic Model of an IP Routing/TE Policy Enforcement Scheme The use of the COPS protocol for dynamically enforcing an IP routing/TE policy yields the generic model depicted in figure 1. Jacquenet Experimental - Expires August 2004 [Page 4]
Internet Draft COPS Usage for Traffic Engineering February 2004 +----------------+ | | | IP Router | | | | +-----+ | COPS-PR +-----+ +-----------+ | | PEP |<---|-------------->| PDP |<-->| IP TE PIB | | +-----+ | +-----+ +-----------+ | | | | | | | +-----+ | | | LPDP| | | +-----+ | | | | | | | | /-------\ | | | | | | +-----+ +-----+| | | RIB |.| RIB || | +-----+ +-----+| | | | | | | | | | \-------/ | | | | | +-----+ | | | FIB | | | +-----+ | +----------------+ Figure 1: Generic model of an IP routing/TE policy enforcement scheme. As depicted in figure 1, the routers embed the following components: - A PEP capability, which supports the TE client-type. The support of the TE client-type is notified by the PEP to the PDP, and is unique for the area covered by the IP routing/traffic engineering policy, so that the PEP can treat all the COPS client-types it supports as non-overlapping and independent namespaces, - A Local Policy Decision Point (LPDP), which can be somewhat compared to the routing processes that have been activated in the router. The LPDP will therefore contribute to the computation and the selection of the IP routes (see section 6 of this draft), - Several instances of Routing Information Bases (RIB), according to the different (unicast and multicast) routing processes that have been activated - one can easily assume the activation of at least one IGP (Interior Gateway Protocol, like OSPF) and BGP4, - Conceptually one Forwarding Information Base (FIB), which will store the routes that have been selected by the routing processes, but this draft makes no assumption about the number of FIBs that Jacquenet Experimental - Expires August 2004 [Page 5]
Internet Draft COPS Usage for Traffic Engineering February 2004 can be supported by a router (e.g. within the context of an IP VPN (Virtual Private Network) service offering). As suggested in [14], the enforcement of an IP routing/traffic engineering policy is based upon the use of a policy server (the PDP in the above figure) that sends IP TE-related information towards the PEP capability embedded in the IP router. The TE-related information is stored and maintained in an TE Policy Information Base ([15]), which will be accessed by the PDP to retrieve and update the TE-related information whenever necessary (see section 6 of this draft). Also, this TE-related information is conveyed between the PDP and the PEP thanks to the establishment of a COPS-PR connection between these two entities. The COPS-PR protocol assumes a named data structure (the PIB), so as to identify the type and purpose of the policy information that is sent by the PDP to the PEP for the provisioning of a given policy. Within the context of this draft, the data structure of the PIB refers to the IP routing/TE policy that is described in the PIB as a collection of PRovisioning Classes (PRC). Furthermore, these classes contain attributes that actually describe the TE-related policy provisioning data that will be sent by the PDP to the PEP. Some of these attributes consist of the link and traffic engineering metrics that will be manipulated by the routing processes being activated in the routers to compute the IP routes. The TE classes are instantiated as multiple PRI (PRovisioning Instance) instances, each of which being identified by PRovisioning Instance iDentifier (PRID). A given PRI specifies the data content carried in the TE client specific objects. A TE PRI typically contains a value for each attribute that has been defined for the TE PRC. Currently, the TE PIB has identified a per-DSCP TE PRC instantiation scheme, because the DSCP value conveyed in each IP datagram that will be processed by the routers privileges the notion of "DSCP-based" routing. Such a routing scheme aims at reflecting the IP routing/TE policies that have been defined by a service provider, assuming a restricted number of DSCP-identified classes of service that will service the customers' requirements. 5. TE Client-Type Specific Information to be Carried in COPS Messages This section describes the formalism that is specific to the use of a TE client-type, given that only the COPS messages that require a TE client-type specific definition are described in this section, i.e. the other COPS messages to be exchanged between a PEP that supports the TE client-type and a PDP, and which do not need to carry TE Jacquenet Experimental - Expires August 2004 [Page 6]
Internet Draft COPS Usage for Traffic Engineering February 2004 client-type specific information, are those described in the corresponding [2] and [3] documents, without any further elaboration. It must be noted that, whatever the contents of the COPS messages that MAY be exchanged between the PEP supporting the TE client-type and the PDP, the actual calculation, selection, installation, maintenance and possible withdrawal of IP routes in the router's FIB is left to the routers. Nevertheless, the information contained in the router's FIB MUST be consistent with the information contained in the TE PIB: this is done thanks to the synchronization features of the COPS architecture, as defined in [2]. 5.1. Client-Type Field of the Common Header of Every COPS Message All of the TE client-type COPS messages MUST contain the COPS Common Header with the 2-byte encoded Client-Type field valued with the yet- to-be assigned IANA number (see section 7 of this draft) for the TE client-type. 5.2. COPS Message Content 5.2.1. Request Messages (REQ) The REQ message is sent by the TE client-type to issue a configuration request to the PDP, as specified in the COPS Context Object. The REQ message includes the current configuration information related to the enforcement of an IP routing/TE policy. Such configuration information is encoded according to the ClientSI format that is defined for the Named ClientSI object of the REQ message. The configuration information is encoded as a collection of bindings that associate a PRID object and an Encoded Provisioning Instance Data (EPD). Such information MAY consist of: - The identification information of the router, e.g. the identification information that is conveyed in OSPF LSA (Link State Advertisement) Type 1 messages. The use of a loopback interface's IP address is highly recommended for the instantiation of the corresponding EPD, - The link metric values that have been currently assigned to each (physical/logical) interface of the router, as described in [4] for example. Such values MAY vary with an associated DSCP value, i.e. the link metric assigned to an interface is a function of the DSCP value encoded in each IP datagram that this router may have to forward, Jacquenet Experimental - Expires August 2004 [Page 7]
Internet Draft COPS Usage for Traffic Engineering February 2004 - The traffic engineering metric values that specify the link metric values for traffic engineering purposes, as defined in [7], for example. These values MAY be different from the above-mentioned link metric values and they MAY also vary according to DSCP values. 5.2.2. Decision Messages (DEC) The DEC messages are used by the PDP to send TE policy provisioning data to the TE client-type. DEC messages are sent in response to a REQ message received from the PEP, or they can be unsolicited, e.g. subsequent DEC messages can be sent at any time after, to supply the PEP with additional or updated TE policy configuration information without the solicited message flag set in the COPS message header, since such messages correspond to unsolicited decisions. DEC messages typically consist of "install" and/or "remove" decisions, and, when there is no Decision Flags set, the DEC message includes the Named Decision Data (Provisioning) object. Apart from the aforementioned identification information, and according to the kind of (PRID, EPD) bindings that MAY be processed by the PEP (see section 5.2.1. of the draft), DEC messages MAY refer to the following decision examples: - Assign new link/traffic engineering metric values each time a new interface is installed/created on the router. These new values will obviously yield the generation of LSA messages in the case of the activation of the OSPF protocol, and/or the generation of BGP4 UPDATE messages (e.g. in the case of a new instantiation of the MULTI_EXIT_DISC (MED) attribute). This will in turn yield the computation of (new) IP routes that MAY be installed in the router's FIB, - Modify previously assigned metric values, thanks to a remove/install decision procedure (this may yield a modification of the router's FIB as well, obviously), - Remove assigned metric values, e.g. the corresponding interfaces may not be taken into consideration by the routing algorithms anymore (or during a specific period of time, e.g. for maintenance purposes). 5.2.3. Report Messages (RPT) The Report message allows the PEP to notify the PDP with a particular set of IP routing/TE policy provisioning instances that have been successfully or unsuccessfully installed/removed. When the PEP receives a DEC message from the PDP, it MUST send back a RPT message towards the PDP. The RPT message will contain one of the following Report-Types: Jacquenet Experimental - Expires August 2004 [Page 8]
Internet Draft COPS Usage for Traffic Engineering February 2004 "Failure": Notification of errors that occurred during the processing of the (PRID, EPD) bindings contained in the DEC message. Such a notification procedure can include a failure report in assigning an updated value of a given metric for example, "Success": Notification of successful assignment of metric values, and/or successful installation of IP routes in the router's FIB. From this perspective, there MAY be routes that will be installed in the router's FIB without any explicit decision sent by the PDP to the PEP regarding the calculation/installation of the aforementioned route. This typically reflects a normal dynamic routing procedure, whenever route advertisement messages are received by the router, including messages related to a topology change. In any case (i.e. whatever the effect that yielded the installation of a route in the router's FIB), a RPT message MUST be sent by the PEP towards the PDP to notify such an event, so that the TE PIB will be updated by the PDP accordingly. "Accounting": The accounting RPT message will carry statistical information related to the traffic that will transit through the router. This statistical information MAY be used by the PDP to possibly modify the metric values that have been assigned when thresholds have been crossed: for example, if the RPT message reports that x % of the available rate associated to a given interface have been reached, then the PDP MAY send an unsolicited DEC message in return, so that potential bottlenecks be avoided. 5.3. Backward Compatibility Issues In the case where the IP network is composed of COPS-aware routers (which embed a PEP capability that supports the TE client-type), as well as COPS-unaware routers, the activation of a link state routing protocol (like OSPF) together with the reporting mechanism that has been described in section 5.2. of this draft addresses the backward compatibility issue. Indeed, the flooding mechanism that is used by the OSPF protocol for the propagation of the LSA messages assumes that, in particular, the COPS-aware routers will receive these update messages. Upon receipt of such messages, the PEP will have the ability to notify the PDP with the corresponding changes (e.g. by using a "Success" report-type that will reflect the installation of new routes in the router's FIB), so that the TE PIB can be updated accordingly. Jacquenet Experimental - Expires August 2004 [Page 9]
Internet Draft COPS Usage for Traffic Engineering February 2004 The same observation can be made within the context of the activation of the BGP4 protocol, because of the iBGP full-mesh topology that is required to allow the routers of a given domain to get a homogeneous view of the "outside" world. 6. COPS-PR Usage of the TE Client-Type After having opened a COPS connection with the PDP, the PEP sends a REQ message towards the PDP that will contain a Client Handle. The Client Handle is used to identify a specific request state associated to the TE client-type supported by the PEP. The REQ message will contain a "Configuration Request" context object. This REQ message will also carry the named client specific information (including the (default) configuration information), as described in section 5.2.1.of the draft. Default configuration information includes the information available during the bootstrap procedures of the routers. The routes that have been installed in the router's FIB MAY be conveyed in specific (PRID, EPD) bindings in the REQ message as well. Upon receipt of the REQ message, the PDP will send back a DEC message towards the PEP. This DEC message will carry TE Named Decision Data object that will convey all the appropriate installation/removal of (PRID, EPD), as described in section 5.2.2 of this draft. One of the basic goals of this named Decision objects consists in making the routers enforce a given IP routing/TE policy. Upon receipt of a DEC message, the TE-capable PEP will (try to) apply the corresponding decisions, by making the network device (and its associated implementation-specific Command Line Interface, if necessary) install the named TE policy data (e.g. assign a metric value to a recently-installed interface). Then, the PEP will notify the PDP about the actual enforcement of the named TE policy decision data, by sending the appropriate RPT message back to the PDP. Depending on the report-type that will be carried in the RPT message, the contents of the message MAY include: - Successfully/unsuccessfully assigned new/updated metric values, - Successfully installed routes from the router's FIB. Note that the notion of "unsuccessfully installed routes" is meaningless, - Successfully/unsuccessfully withdrawn routes from the router's FIB. Route withdrawal is not only subject to the normal IGP and BGP4 procedures (thus yielding the generation of the corresponding advertisement messages), but also subject to named TE policy decision data (carried in a specific DEC message), like those data related to the lifetime of a service. Jacquenet Experimental - Expires August 2004 [Page 10]
Internet Draft COPS Usage for Traffic Engineering February 2004 The RPT message MAY also carry the "Accounting" report-type, as described in section 5.2.3.of this draft. 7. IANA Considerations Section 5.1 of this draft has identified the need for the assignment of a specific number that will uniquely identify the TE client-type in every COPS message to be exchanged between a PEP and a PDP. This value SHOULD be chosen in the range of 0x8000 - 0xFFFF,according to a First Come First Served policy, as mentioned in both [2] and [16]. 8. Security Considerations This draft specifies a new client-type that will make use of the COPS protocol for the provisioning and the enforcement of IP routing/TE policies. As such, it introduces no new security issues over the COPS protocol itself, or its usage for policy provisioning. Nevertheless, it is recommended that the TE client-type systematically uses the Message Integrity Object (Integrity) for the authentication and the validation of every COPS message it may exchange with the PDP with whom it has established a COPS communication. The Message Integrity Object also prevents from replay attacks. In addition, the IP Security ([17]) protocol suite may be activated, and the IPSec Authentication Header (AH) should be used for the validation of the COPS connection, while the Encapsulated Security Payload (ESP) may be used to provide both validation and secrecy, as stated in [2]. 9. References [1] Bradner, S.,"The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. [2] Boyle, J., Cohen, R., Durham, D., Herzog, S., Raja R., Sastry A., "The COPS (Common Open Policy Service) Protocol", RFC 2748, January 2000. [3] Ho Chan, K., Durham, D., Gai, S., Herzog, S., McLoghrie, K., Reichmeyer, F., Seligson, J., Smith, A., Yavatkar, R., "COPS Usage for Policy Provisioning (COPS-PR)", RFC 3084, March 2001. [4] Moy, J.,"OSPF Version 2", RFC 2328, April 1998. [5] Rekhter, Y., Li T., "A Border Gateway Protocol 4 (BGP-4)", RFC 1771, March 1995. [6] Jacquenet, C., Proust, C., "An Introduction to IP Multicast Traffic Engineering", Proceedings of the ECUMN 2002 conference. See http://iutsun1.colmar.uha.fr/ECUMN02.html for further details. [7] Katz, D., Yeung, D., Kompella, K., "Traffic Engineering Extensions to OSPF", RFC 3630, September 2003. Jacquenet Experimental - Expires August 2004 [Page 11]
Internet Draft COPS Usage for Traffic Engineering February 2004 [8] Smit, H., Li T., "IS-IS Extensions for Traffic Engineering", draft-ietf-isis-traffic-05.txt, Work in Progress, August 2003. [9] ISO/IEC 10589, "Intermediate System to Intermediate System, Intra-Domain Routing Exchange Protocol for use in Conjunction with the Protocol for Providing the Connectionless-mode Network Service (ISO 8473)", June 1992. [10] Jacquenet, C., Cristallo, G., "The BGP QOS_NLRI Attribute", draft-jacquenet-bgp-qos-00.txt, Work in Progress, February 2004. [11] Yavatkar, R., Pendarakis, D., Guerin, R., "A Framework for Policy-Based Admission Control", RFC 2753, January 2000. [12] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [13] Nichols K., Blake S., Baker F., Black D., "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC 2474, December 1998. [14] Apostopoulos G., Guerin R., Kamat S., Tripathi S. K., "Server Based QOS Routing", Proceedings of the 1999 GLOBCOMM Conference. [15] Boucadair, M., Jacquenet, C., "An IP Forwarding Policy Information Base", draft-jacquenet-fwd-pib-00.txt, Work in Progress, February 2004. [16] Alvestrand H., Narten T., "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. [17] Atkinson R., "Security Architecture for the Internet Protocol", RFC 2401, August 1998. 10. Acknowledgments Part of this work is funded by the European Commission, within the context of the MESCAL (Management of End-to-End Quality of Service Across the Internet At Large, http://www.mescal.org) project, which is itself part of the IST (Information Society Technologies) research program. The author would also like to thank all the partners of the MESCAL project for the fruitful discussions that have been conducted so far within the context of the traffic engineering specification effort of the project, as well as MM. Boucadair and Brunner for their valuable input. 11. Author's Address Christian Jacquenet France Telecom 3, avenue Franois Chteau CS 36901 35069 Rennes CEDEX France Phone: +33 2 99 87 63 31 Email: christian.jacquenet@francetelecom.com Jacquenet Experimental - Expires August 2004 [Page 12]
Internet Draft COPS Usage for Traffic Engineering February 2004 12. Full Copyright Statement Copyright(C) The Internet Society (2004). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Jacquenet Experimental - Expires August 2004 [Page 13]
Network Working Group M. Boucadair Internet Draft C. Jacquenet Document: draft-jacquenet-fwd-pib-00.txt France Telecom Category: Experimental February 2004 Expires August 2004 An IP Forwarding Policy Information Base <draft-jacquenet-fwd-pib-00.txt> Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC 2026 [1]. 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. Abstract This draft specifies a set of Policy Rule Classes (PRC) for the enforcement of an IP forwarding policy by network devices. Instances of such classes reside in a virtual information store, which is called the IP Forwarding Policy Information Base (PIB). The corresponding IP forwarding policy provisioning data are intended for use by a COPS-PR TE Client-Type, and they complement the PRC classes that have been defined in the Framework PIB. Table of Contents 1. Introduction...............................................2 2. Conventions used in this document..........................3 3. PIB Overview...............................................3 4. The IP Forwarding Policy Information Base..................4 5. Security Considerations....................................9 6. References.................................................9 7. Acknowledgments...........................................10 8. Authors' Addresses........................................10 9. Full Copyright Statement..................................11 Jacquenet et al. Experimental - Expires August 2004 [Page 1]
Internet Draft An IP Forwarding PIB February 2004 1. Introduction The deployment of value-added IP services over the Internet has become one of the most competing challenges for service providers, as well as a complex technical issue. Within the context of network resource provisioning and allocation, the Common Open Policy Service protocol (COPS, [2]) and its usage for the support of Policy Provisioning ([3]) is one of the most promising candidate protocols that should help service providers in dynamically enforcing IP routing and traffic engineering policies. An IP routing/TE policy consists in appropriately provisioning and allocating/de-allocating the switching and the transmission resources of an IP network (i.e. the routers and the links that connect these routers, respectively), according to e.g. rate, one-way delay, inter- packet delay variation, etc.) that have been possibly negotiated between the customers and the service providers, and according to (a set of)routing metrics, which can also reflect the network conditions. Thus, the enforcement of IP routing/TE policies yields the need for an introduction of a high level of automation for the dynamic provisioning of the configuration data that will be taken into account by the routers to select the appropriate IP routes. Within the context of this document, the actual enforcement of an IP forwarding policy is primarily based upon the activation of both intra- and inter-domain dynamic routing protocols that will be activated by the routers to select, install, maintain and possibly withdraw IP routes. Such routes have been selected so that they comply as much as possible with the aforementioned QoS requirements and/or specific routing constraints, possibly depending on the type of traffic that will be conveyed along these routes. It is therefore necessary to provide the route selection processes with the information that will depict the routing policies that are to be enforced within a domain and, whenever appropriate, the aforementioned constraints and metrics, given the dynamic routing protocols actually support traffic engineering capabilities for the calculation and the selection of such routes. Some of these capabilities are currently being specified in [4] and [5] for the OSPF (Open Shortest Path First) and the IS-IS (Intermediate System to Intermediate System routing protocol, [6]) interior routing protocols respectively, while there is a comparable effort for the BGP4 (Border Gateway Protocol, version 4) protocol, as described in [7], for example. Jacquenet et al. Experimental - Expires August 2004 [Page 2]
Internet Draft An IP Forwarding PIB February 2004 To provide the route selection processes with the aforementioned information, one possibility is to use the COPS-PR protocol, together with a collection of policy provisioning data that will be stored in a virtual information store, called a Policy Information Base. This draft describes a collection of Policy Rule Classes that will be stored and dynamically maintained in an IP forwarding PIB. The "rule" and "role" concepts, which have been defined in [8], are adopted by this document to distribute the IP routing policy provisioning data over the COPS-PR protocol. The corresponding IP forwarding policy provisioning data are intended for use by a COPS-PR TE Client-Type ([9]), and they complement the PRC classes that have been defined in the Framework PIB ([10]). This document is organized as follows: - Section 3 provides an overview of the organization of the IP forwarding PIB, - Section 4 provides a description of the PRC classes of the IP forwarding PIB, according to the semantics of the Structure of Policy Provisioning Information (SPPI, [11]). 2. Conventions used in this document 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 RFC 2119 [12]. 3. PIB Overview The dynamic enforcement of an IP forwarding policy relies upon the activation of intra- and inter-domain routing protocols that will have the ability to take into account configuration information for the computation and the selection of routes, which will comply as much as possible with the constraints and requirements that MAY have been contractually defined between customers and service providers. This document specifies an IP forwarding PIB that mainly aims at storing and maintaining the information related to the IP routes that have been installed in the routers' Forwarding Information Bases, so that service providers maintain and update the adequate knowledge of the network's resources availability, from an IP routing perspective. As such, this PIB has been designed so that it SHOULD be gracefully complemented by PIB modules that will reflect the IGP- and BGP- inferred routing policies to be enforced, in terms of cost metrics' values to be assigned and updated whenever needed. Also, the accounting PIB module which is described in [13] aims at providing the most accurate feedback (to service providers) on how Jacquenet et al. Experimental - Expires August 2004 [Page 3]
Internet Draft An IP Forwarding PIB February 2004 efficient the enforcement of a given IP forwarding policy (as specified in this document) actually is. The choice of this PIB organization is basically twofold: - Make the PIB implementation simple, - Provide the appropriate granularity of policy provisioning data that will be manipulated according to the requirements and technical choices of service providers. Therefore, the IP forwarding PIB is currently organized into the following provisioning classes: 1. The Forwarding Classes (ipFwdClasses): the information contained in these classes is meant to provide a detailed description of the IP routes as they have been selected by the routers of a given domain, 2. The Statistics Classes (ipFwdStatsClasses): the information contained in these classes is meant to provide statistics on the use of the IP routes currently depicted in the IP forwarding PIB. 4. The IP Forwarding Policy Information Base IP-FWD-PIB PIB-DEFINITIONS ::= BEGIN IMPORTS Unsigned32, Integer32, MODULE-IDENTITY, MODULE-COMPLIANCE, OBJECT-TYPE, OBJECT-GROUP FROM COPS-PR-SPPI InstanceId, ReferenceId, Prid, TagId FROM COPS-PR-SPPI-TC InetAddress, InetAddressType FROM INET-ADDRESS-MIB Count, TEXTUAL-CONVENTION FROM ACCT-FR-PIB-TC TruthValue, TEXTUAL-CONVENTION FROM SNMPv2-TC RoleCombination, PrcIdentifier FROM FRAMEWORK-ROLE-PIB SnmpAdminString FROM SNMP-FRAMEWORK-MIB; ipFwdPib MODULE-IDENTITY SUBJECT-CATEGORIES { tbd } -- TE client-type to be -- assigned by IANA LAST-UPDATED "200301220900Z" ORGANIZATION "France Telecom" Jacquenet et al. Experimental - Expires August 2004 [Page 4]
Internet Draft An IP Forwarding PIB February 2004 CONTACT-INFO " Mohamed Boucadair France Telecom R & D 42, rue des Coutures BP 6243 14066 CAEN CEDEX 04 France Phone: +33 2 31 75 92 31 E-Mail: mohamed.boucadair@francetelecom.com" DESCRIPTION "The PIB module containing a set of policy rule classes that describe the IP routes that have been computed by means of routing/TE policy enforcement, as well as route traffic statistics." REVISION "200402041000Z" DESCRIPTION "Initial version." ::= { pib tbd } -- tbd to be assigned by IANA ipFwdClasses OBJECT IDENTIFIER ::= { ipFwdPib 1 } ipFwdStatsClasses OBJECT IDENTIFIER ::= { ipFwdPib 2 } -- -- Forwarding classes. The information contained in these classes -- is meant to provide a detailed description of the available IP -- routes. One table has been specified so far, but there is room -- for depicting different kinds of routes, like MPLS (MultiProtocol -- Label Switching, ([14]) LSP (Label switched Paths) paths. -- -- -- -- -- The ipFwdTable -- ipFwdTable OBJECT-TYPE SYNTAX SEQUENCE OF ipRouteEntry PIB-ACCESS notify STATUS current DESCRIPTION "This table describes the IP routes that are installed in the forwarding tables of the routers." ::= { ipFwdClasses 1 } ipRouteEntry OBJECT-TYPE SYNTAX ipRouteEntry Jacquenet et al. Experimental - Expires August 2004 [Page 5]
Internet Draft An IP Forwarding PIB February 2004 STATUS current DESCRIPTION "A particular route to a particular destination." PIB-INDEX { ipRoutePrid } UNIQUENESS { ipRouteDest, ipRouteMask, ipRoutePhbId, ipRouteNextHopAddress ipRouteNextHopMask ipRouteIfIndex } ::= { ipFwdTable 1 } ipRouteEntry ::= SEQUENCE { ipRoutePrid InstanceId, ipRouteDestAddrType InetAddressType, ipRouteDest InetAddress, ipRouteMask Unsigned32, ipRouteNextHopAddrType InetAddressType, ipRouteNextHopAddress InetAddress, ipRouteNextHopMask Unsigned32, ipRoutePhbId Integer32, ipRouteOrigin Integer32, ipRouteIfIndex Unsigned32 } ipRoutePrid OBJECT-TYPE SYNTAX InstanceId STATUS current DESCRIPTION "An integer index that uniquely identifies this route entry among all the route entries." ::= { ipRouteEntry 1 } ipRouteDestAddrType OBJECT-TYPE SYNTAX InetAddressType STATUS current DESCRIPTION "The address type enumeration value ([15]) used to specify the type of a route's destination IP address." ::= { ipRouteEntry 2 } ipRouteDest OBJECT-TYPE SYNTAX InetAddress STATUS current DESCRIPTION Jacquenet et al. Experimental - Expires August 2004 [Page 6]
Internet Draft An IP Forwarding PIB February 2004 "The IP address to match against the packet's destination address." ::= { ipRouteEntry 3 } ipRouteMask OBJECT-TYPE SYNTAX Unsigned32 (0..128) STATUS current DESCRIPTION "Indicates the length of a mask for the matching of the destination IP address. Masks are constructed by setting bits in sequence from the most-significant bit downwards for ipRouteMask bits length. All other bits in the mask, up to the number needed to fill the length of the address ipRouteDest are cleared to zero. A zero bit in the mask then means that the corresponding bit in the address always matches." ::= { ipRouteEntry 4 } ipRouteNextHopAddrType OBJECT-TYPE SYNTAX InetAddressType STATUS current DESCRIPTION "The address type enumeration value used to specify the type of the next hop's IP address." ::= { ipRouteEntry 5 } ipRouteNextHopAddress OBJECT-TYPE SYNTAX InetAddress STATUS current DESCRIPTION "On remote routes, the address of the next router en route; Otherwise, 0.0.0.0." ::= { ipRouteEntry 6 } ipRouteNextHopMask OBJECT-TYPE SYNTAX Unsigned32 (0..128) STATUS current DESCRIPTION "Indicates the length of a mask for the matching of the next hop's IP address. Masks are constructed by setting bits in sequence from the most-significant bit downwards for ipRouteNextHopMask bits length. All other bits in the mask, up to the number needed to fill the length of the address ipRouteNextHop are cleared to Jacquenet et al. Experimental - Expires August 2004 [Page 7]
Internet Draft An IP Forwarding PIB February 2004 zero. A zero bit in the mask then means that the corresponding bit in the address always matches." ::= { ipRouteEntry 7 } ipRoutePhbId OBJECT-TYPE SYNTAX Integer32 (-1 | 0..63) STATUS current DESCRIPTION "The binary encoding that uniquely identifies a Per Hop Behaviour (PHB, [16]) or a set of PHBs associated to the DiffServ Code Point (DSCP) marking of the IP datagrams that will be conveyed along this route. A value of -1 indicates that a specific PHB ID value has not been defined, and thus, all PHB ID values are considered a match." ::= { ipRouteEntry 8 } ipRouteOriginOBJECT-TYPE SYNTAX INTEGER { OSPF (0) IS-IS (1) BGP (2) STATIC (3) OTHER (4) } STATUS current DESCRIPTION "The value indicates the origin of the route. Either the route has been computed by OSPF, by IS-IS, announced by BGP4, is static, or else." ::= { ipRouteEntry 9 } ipRouteIfIndex OBJECT-TYPE SYNTAX Unsigned32 (0..65535) STATUS current DESCRIPTION "The ifIndex value that identifies the local interface through which the next hop of this route is accessible." ::= { ipRouteEntry 10 } -- -- Route statistics classes. The information contained -- in the yet-to-be defined tables aim at reporting statistics about -- COPS control traffic, route traffic and potential errors. The Jacquenet et al. Experimental - Expires August 2004 [Page 8]
Internet Draft An IP Forwarding PIB February 2004 -- next version of the draft will provide a first table that will be -- based upon the use of the "count" clause. -- -- END 5. Security Considerations The traffic engineering policy provisioning data as they are described in this PIB will be used for configuring the appropriate network elements that will be involved in the dynamic enforcement of the corresponding routing and traffic engineering policies, by means of a COPS-PR communication that will convey this information. The function of dynamically provisioning network elements with such configuration information implies that only an authorized COPS-PR communication takes place. From this perspective, this draft does not introduce any additional security issues other than those that have been identified in the COPS-PR specification, and it is therefore recommended that the IPSec ([17]) protocol suite be used to secure the above-mentioned authorized communication. 6. References [ [1] Bradner,] S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. [2] Boyle, J., Cohen, R., Durham, D., Herzog, S., Raja R., Sastry A., "The COPS (Common Open Policy Service) Protocol", RFC 2748, Proposed Standard, January 2000. [3] Ho Chan, K., Durham, D., Gai, S., Herzog, S., McLoghrie, K., Reichmeyer, F., Seligson, J., Smith, A., Yavatkar, R., "COPS Usage for Policy Provisioning (COPS-PR)", RFC 3084, March 2001. [4] Katz, D., Yeung, D., Kompella, K., "Traffic Engineering Extensions to OSPF", RFC 3630, September 2003. [5] Smit, H., Li, T., "IS-IS Extensions for Traffic Engineering", draft-ietf-isis-traffic-05.txt, Work in Progress, August 2003. [6] ISO/IEC 10589, "Intermediate System to Intermediate System, Intra-Domain Routing Exchange Protocol for use in Conjunction with the Protocol for Providing the Connectionless-mode Network Service (ISO 8473)", June 1992. [7] Jacquenet, C., "The BGP QOS_NLRI Attribute", draft-jacquenet- bgp-qos-00.txt, Work in Progress, February 2004. [8] Moore, B. et al., "Policy Core Information Model -- Version 1 Specification", RFC 3060, February 2001. [9] Jacquenet, C., "A COPS Client-Type for Traffic Engineering", draft-jacquenet-cops-te-00.txt, Work in Progress, February 2004. Jacquenet et al. Experimental - Expires August 2004 [Page 9]
Internet Draft An IP Forwarding PIB February 2004 [10] Sahita, R., et al., "Framework Policy Information Base", RFC 3318, March 2003. [11] McLoghrie, K., et al., "Structure of Policy Provisioning Information (SPPI)", RFC 3159, August 2001. [12] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 [13] Boucadair, M., "An IP TE PIB for Accounting purposes", draft- boucadair-ipte-acct-pib-02.txt, Work in Progress, June 2003. [14] Rosen, E., et al., "Multiprotocol Label Switching Architecture", RFC 3031, January 2001. [15] Daniele, M., Haberman, B., Routhier, S., Schoenwaelder, J., "Textual Conventions for Internet Network Addresses", RFC 3291, May 2002. [16] Black, D., Brim, S., Carpenter, B., Le Faucheur, F., "Per Hop Behaviour Identification Codes", RFC 3140, June 2001. [17] Kent, S., Atkinson, R., "Security Architecture for the Internet Protocol", RFC 2401, November 1998. 7. Acknowledgments Part of this work is funded by the European Commission, within the context of the MESCAL (Management of End-to-End Quality of Service Across the Internet At Large, http://www.mescal.org) project, which is itself part of the IST (Information Society Technologies) research program. The authors would also like to thank all the partners of the MESCAL project for the fruitful discussions that have been conducted so far within the context of the traffic engineering specification effort of the project. 8. Authors' Addresses Mohamed Boucadair France Telecom R & D DMI/SIR 42, rue des Coutures BP 6243 14066 Caen Cedex 4 France Phone: +33 2 31 75 92 31 Email: mohamed.boucadair@francetelecom.com Christian Jacquenet France Telecom 3, avenue Franois Chteau CS 36901 35069 Rennes CEDEX France Phone: +33 2 99 87 63 31 Email: christian.jacquenet@francetelecom.com Jacquenet et al. Experimental - Expires August 2004 [Page 10]
Internet Draft An IP Forwarding PIB February 2004 9. Full Copyright Statement Copyright (C) The Internet Society (2004). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist its implementation may be prepared, coed, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Jacquenet et al. Experimental - Expires August 2004 [Page 11]
Network Working Group G. Cristallo Internet Draft Alcatel Document: draft-jacquenet-bgp-qos-00.txt C. Jacquenet Category: Experimental France Telecom Expires August 2004 February 2004 The BGP QOS_NLRI Attribute <draft-jacquenet-bgp-qos-00.txt> Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC 2026 [1]. 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. NOTE: a PDF version of this document (which includes the figures mentioned in section 7) can be accessed at http://www.mescal.org. Abstract This draft specifies an additional BGP4 (Border Gateway Protocol, version 4) attribute, named the "QOS_NLRI" attribute, which aims at propagating QoS (Quality of Service)-related information associated to the NLRI (Network Layer Reachability Information) information conveyed in a BGP UPDATE message. Table of Contents 1. Conventions Used in this Document..........................2 2. Introduction...............................................2 3. Basic Requirements.........................................3 4. The QOS_NLRI Attribute (Type Code tbd*)....................3 5. Operation..................................................7 6. Use of Capabilities Advertisement with BGP-4...............8 7. Simulation Results.........................................8 Jacquenet Experimental - Expires August 2004 [Page 1]
Internet Draft The QOS_NLRI Attribute February 2004 7.1. A Phased Approach..........................................8 7.2. A Case Study..............................................10 7.3. Additional Results........................................11 7.4. Next Steps................................................12 8. IANA Considerations.......................................12 9. Security Considerations...................................12 10. References................................................13 11. Acknowledgments...........................................13 12. Authors' Addresses........................................14 13. Full Copyright Statement..................................14 1. Conventions Used in this Document 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 RFC 2119 [2]. 2. Introduction Providing end-to-end quality of service is one of the most important challenges of the Internet, not only because of the massive development of value-added IP service offerings, but also because of the various QoS policies that are currently enforced within an autonomous system, and which may well differ from one AS (Autonomous System) to another. For the last decade, value-added IP service offerings have been deployed over the Internet, thus yielding a dramatic development of the specification effort, as far as quality of service in IP networks is concerned. Nevertheless, providing end-to-end quality of service across administrative domains still remains an issue, mainly because: - QoS policies may dramatically differ from one service provider to another, - The enforcement of a specific QoS policy may also differ from one domain to another, although the definition of a set of common quality of service indicators may be shared between the service providers. Activate the BGP4 protocol ([3]) for exchanging reachability information between autonomous systems has been a must for many years. Therefore, disseminating QoS information coupled with reachability information in a given BGP UPDATE message appears to be helpful in enforcing an end-to-end QoS policy. This draft aims at specifying a new BGP4 attribute, the QOS_NLRI attribute, which will convey QoS-related information associated to the routes described in the corresponding NLRI field of the attribute. Jacquenet Experimental - Expires August 2004 [Page 2]
Internet Draft The QOS_NLRI Attribute February 2004 This document is organized according to the following sections: - Section 3 describes the basic requirements that motivate the approach, - Section 4 describes the attribute, - Section 5 elaborates on the mode of operation, - Section 6 elaborates on the use of the capabilities advertisement feature of the BGP4 protocol, - Section 7 depicts the results of a simulation work, - Finally, sections 8 and 9 introduce IANA and some security considerations, respectively. 3. Basic Requirements The choice of using the BGP4 protocol for exchanging QoS information between domains is not only motivated by the fact BGP is currently the only inter-domain (routing) protocol activated in the Internet, but also because the manipulation of attributes is a powerful means for service providers to disseminate QoS information with the desired level of precision. The approach presented in this draft has identified the following requirements: - Keep the approach scalable. The scalability of the approach can be defined in many ways that include the convergence time taken by the BGP peers to reach a consistent view of the network connectivity, the number of route entries that will have to be maintained by a BGP peer, the dynamics of the route announcement mechanism (e.g., how frequently and under which conditions should an UPDATE message containing QoS information be sent?), etc. - Keep the BGP4 protocol operation unchanged. The introduction of a new attribute should not affect the way the protocol operates, but the information contained in this attribute may very well influence the BGP route selection process. - Allow for a smooth migration. The use of a specific BGP attribute to convey QoS information should not constrain network operators to migrate the whole installed base at once, but rather help them in gradually deploying the QoS information processing capability. 4. The QOS_NLRI Attribute (Type Code tbd*) (*): "tbd" is subject to the IANA considerations section of this draft. Jacquenet Experimental - Expires August 2004 [Page 3]
Internet Draft The QOS_NLRI Attribute February 2004 The QOS_NLRI attribute is an optional transitive attribute that can be used: 1. To advertise a QoS route to a peer. A QoS route is a route that meets one or a set of QoS requirement(s) to reach a given (set of) destination prefixes. Such QoS requirements can be expressed in terms of minimum one-way delay ([4]) to reach a destination, the experienced delay variation for IP datagrams that are destined to a given destination prefix ([5]), the loss rate experienced along the path to reach a destination, and/or the identification of the traffic that is expected to use this specific route (identification means for such traffic include DSCP (DiffServ Code Point, [6]) marking). These QoS requirements can be used as an input for the BGP route calculation process, 2. To provide QoS-related information along with the NLRI information in a single BGP UPDATE message. It is assumed that this information will be related to the route (or set of routes) described in the NLRI field of the attribute. From a service provider's perspective, the choice of defining the QOS_NLRI attribute as an optional transitive attribute is motivated by the fact that this kind of attribute allows for gradual deployment of the dissemination of QoS-related information by BGP4: not all the BGP peers are supposed to be updated accordingly, while partial deployment of such QoS extensions can already provide an added value, e.g. in the case where a service provider manages multiple domains, and/or has deployed a BGP confederation ([7]). This draft makes no specific assumption about the means to actually value this attribute, since this is mostly a matter of implementation, but the reader is suggested to have a look on document [8], as an example of a means to feed the BGP peer with the appropriate information. The QOS_NLRI attribute is encoded as follows: +---------------------------------------------------------+ | QoS Information Code (1 octet) | +---------------------------------------------------------+ | QoS Information Sub-code (1 octet) | +---------------------------------------------------------+ | QoS Information Value (2 octets) | +---------------------------------------------------------+ | QoS Information Origin (1 octet) | +---------------------------------------------------------+ | Address Family Identifier (2 octets) | +---------------------------------------------------------+ | Subsequent Address Family Identifier (1 octet) | +---------------------------------------------------------+ | Network Address of Next Hop (4 octets) | +---------------------------------------------------------+ | Flags (1 octet) | Jacquenet Experimental - Expires August 2004 [Page 4]
Internet Draft The QOS_NLRI Attribute February 2004 +---------------------------------------------------------+ | Identifier (2 octets) | +---------------------------------------------------------+ | Length (1 octet) | +---------------------------------------------------------+ | Prefix (variable) | +---------------------------------------------------------+ The use and meaning of the fields of the QOS_NLRI attribute are defined as follows: - QoS Information Code: This field carries the type of the QOS information. The following types have been identified so far: (0) Reserved (1) Packet rate, i.e. the number of IP datagrams that can be transmitted (or have been lost) per unit of time, this number being characterized by the elaboration provided in the QoS Information Sub-code (see below) (2) One-way delay metric (3) Inter-packet delay variation (4) PHB Identifier - QoS Information Sub-Code: This field carries the sub-type of the QoS information. The following sub-types have been identified so far: (0) None (i.e. no sub-type, or sub-type unavailable, or unknown sub- type) (1) Reserved rate (2) Available rate (3) Loss rate (4) Minimum one-way delay (5) Maximum one-way delay (6) Average one-way delay The instantiation of this sub-code field MUST be compatible with the value conveyed in the QoS Information code field, as stated in the following table (the rows represent the QoS Information Code possible values, the columns represent the QoS Information Sub-code values identified so far, while the "X" sign indicates incompatibility). Jacquenet Experimental - Expires August 2004 [Page 5]
Internet Draft The QOS_NLRI Attribute February 2004 +---------------------------------------+ | | 0 | 1 | 2 | 3 | 4 | 5 | 6 | +---------------------------------------+ | 0 | | | | | | | | +---------------------------------------+ | 1 | | | | | X | X | X | +---------------------------------------+ | 2 | | X | X | X | | | | +---------------------------------------+ | 3 | | X | X | X | X | X | X | +---------------------------------------+ | 4 | | X | X | X | X | X | X | +---------------------------------------+ - QoS Information Value: This field indicates the value of the QoS information. The corresponding units obviously depend on the instantiation of the QoS Information Code. Namely, if: (a) QoS Information Code field is "0", no unit specified, (b) QoS Information Code field is "1", unit is kilobits per second (kbps), and the rate encoding rule is composed of a 3-bit exponent (with an assumed base of 8) followed by a 13-bit mantissa, as depicted in the figure below: 0 8 16 | | | ----------------- |Exp| Mantissa | ----------------- This encoding scheme advertises a numeric value that is (2^16 -1 - exponential encoding of the considered rate), as depicted in [9]. (c) QoS Information Code field is "2", unit is milliseconds, (d) QoS Information Code field is "3", unit is milliseconds, (e) QoS Information Code field is "4", no unit specified. - QoS Information Origin: This field provides indication on the origin of the path information, as defined in section 4.3.of [3]. - Address Family Identifier (AFI): This field carries the identity of the Network Layer protocol associated with the Network Address that follows. Currently defined values for this field are specified in [10] (see the Address Family Numbers section of this reference document). Jacquenet Experimental - Expires August 2004 [Page 6]
Internet Draft The QOS_NLRI Attribute February 2004 - Subsequent Address Family Identifier (SAFI): This field provides additional information about the type of the prefix carried in the QOS_NLRI attribute. - Network Address of Next Hop: This field contains the IPv4 Network Address of the next router on the path to the destination prefix, (reasonably) assuming that such routers can at least be addressed according to the IPv4 formalism. - Flags, Identifier, Length and Prefix fields: These four fields actually compose the NLRI field of the QOS_NLRI attribute, and their respective meanings are as defined in section 2.2.2 of [11]. 5. Operation When advertising a QOS_NLRI attribute to an external peer, a router may use one of its own interface addresses in the next hop component of the attribute, given the external peer to which one or several route(s) is (are) being advertised shares a common subnet with the next hop address. This is known as a "first party" next hop information. A BGP speaker can advertise to an external peer an interface of any internal peer router in the next hop component, provided the external peer to which the route is being advertised shares a common subnet with the next hop address. This is known as a "third party" next hop information. A BGP speaker that sends an UPDATE message with the QOS_NLRI attribute has the ability to advertise multiple QoS routes, since the Identifier field of the attribute is part of the NLRI description. In particular, the same prefix can be advertised more than once without subsequent advertisements that would replace previous announcements. Since the resolution of the NEXT_HOP address that is always conveyed in a BGP UPDATE message is left to the responsibility of the IGP that has been activated within the domain, the best path according to the BGP route selection process depicted in [3] SHOULD also be advertised. As long as the routers on the path towards the address depicted in the NEXT_HOP attribute of the message have the additional paths depicted in the QOS_NLRI attribute, the propagation of QoS routes within a domain where all the routers are QOS_NLRI aware should not yield inconsistent routing. A BGP UPDATE message that carries the QOS_NLRI MUST also carry the ORIGIN and the AS_PATH attributes (both in eBGP and in iBGP exchanges). Moreover, in iBGP exchanges such a message MUST also Jacquenet Experimental - Expires August 2004 [Page 7]
Internet Draft The QOS_NLRI Attribute February 2004 carry the LOCAL_PREF attribute. If such a message is received from an external peer, the local system shall check whether the leftmost AS in the AS_PATH attribute is equal to the autonomous system number of the peer than sent the message. If that is not the case, the local system shall send the NOTIFICATION message with Error Code UPDATE Message Error, and the Error Sub-code set to Malformed AS_PATH. Finally, an UPDATE message that carries no NLRI, other than the one encoded in the QOS_NLRI attribute, should not carry the NEXT_HOP attribute. If such a message contains the NEXT_HOP attribute, the BGP speaker that receives the message should ignore this attribute. 6. Use of Capabilities Advertisement with BGP-4 A BGP speaker that uses the QOS_NLRI attribute SHOULD use the Capabilities Advertisement procedures, as defined in [12], so that it might be able to determine if it can use such an attribute with a particular peer. The fields in the Capabilities Optional Parameter are defined as follows: - The Capability Code field is set to N (127 < N < 256, when considering the "Private Use" range, as specified in [13]), while the Capability Length field is set to "1". - The Capability Value field is a one-octet field, which contains the Type Code of the QOS_NLRI attribute, as defined in the introduction of section 5 of the present draft. In addition, the multiple path advertisement capability MUST be supported, as defined in section 2.1 of [4]. 7. Simulation Results 7.1. A Phased Approach The simulation work basically aims at qualifying the scalability of the usage of the QOS_NLRI attribute for propagating QoS-related information across domains. This effort also focused on the impact on the stability of the BGP routes, by defining a set of basic engineering rules for the introduction of additional QoS information, as well as design considerations for the computation and the selection of "QoS routes". This ongoing development effort is organized into a step-by-step approach, which consists in the following phases: 1. Model an IP network composed of several autonomous systems. Since this simulation effort is primarily focused on the Jacquenet Experimental - Expires August 2004 [Page 8]
Internet Draft The QOS_NLRI Attribute February 2004 qualification of the scalability related to the use of the QOS_NLRI attribute for exchanging QoS-related information between domains, it has been decided that the internal architecture of such domains should be kept very simple, i.e. without any specific IGP interaction, 2. Within this IP network, there are BGP peers that are QOS_NLRI aware, i.e. they have the ability to process the information conveyed in the attribute, while the other routers are not: the latter do not recognize the QOS_NLRI attribute by definition, and they will forward the information to other peers, by setting the Partial bit in the attribute, meaning that the information conveyed in the message is incomplete. This approach contributes to the qualification of a progressive deployment of QOS_NLRI- aware BGP peers, 3. As far as QOS_NLRI aware BGP peers are concerned, they will process the information contained in the QOS_NLRI attribute to possibly influence the route decision process, thus yielding the selection (and the announcement) of distinct routes towards a same destination prefix, depending on the QoS-related information conveyed in the QOS_NLRI attribute, 4. Modify the BGP route decision process: at this stage of the simulation, the modified decision process relies upon the one- way delay information (which corresponds to the QoS Information Code field of the attribute valued at "2"), and it also takes into account the value of the Partial bit of the attribute. Once the creation of these components of the IP network has been completed (together with the modification of the BGP route selection process), the behavior of a QOS_NLRI-capable BGP peer is as follows. Upon receipt of a BGP UPDATE message that contains the QOS_NLRI attribute, the router will first check if the corresponding route is already stored in its local RIB, according to the value of the one- way delay information contained in both QoS Information Code and Sub- code fields of the attribute. If not, the BGP peer will install the route in its local RIB. Otherwise (i.e. an equivalent route already exists in its database), the BGP peer will select the best of both routes according to the following criteria: - If both routes are said to be either incomplete (Partial bit has been set) or complete (Partial bit is unset), the route with the lowest delay will be selected, - Otherwise, a route with the Partial bit unset is always preferred over any other route, even if this route reflects a higher transit delay. Jacquenet Experimental - Expires August 2004 [Page 9]
Internet Draft The QOS_NLRI Attribute February 2004 If ever both Partial bit and transit delay information are not sufficient to make a decision, the standard BGP decision process (according to the breaking ties mechanism depicted in [3]) is performed. 7.2. A Case Study REMINDER: a PDF version of this document (which includes the figures mentioned in this section) can be accessed at http://www.mescal.org. As stated in the previous section 7.1, the current status of the simulation work basically relies upon the one-way transit delay information only, as well as the complete/incomplete indication of the Partial bit conveyed in the QOS_NLRI attribute. The following figures depict the actual processing of the QoS-related information conveyed in the QOS_NLRI attribute, depending on whether the peer is QOS_NRLI-aware or not. [Fig. 1: A Case Study.] Figure 1 depicts the IP network that has been modelled, while figure 2 depicts the propagation of a BGP UPDATE message that contains the QOS_NLRI attribute, in the case where the contents of the attribute are changed, because of complete/incomplete conditions depicted by the Partial bit of the QOS_NLRI attribute. [Fig. 2: Propagation of One-way Delay Information via BGP4.] Router S in figure 2 is a QOS_NRLI-capable speaker. It takes 20 milliseconds for node S to reach network 192.0.20.0: this information will be conveyed in a QOS_NLRI attribute that will be sent by node S in a BGP UPDATE message with the Partial bit of the QOS_NLRI attribute unset. Router A is another QOS_NLRI BGP peer, and it takes 3 milliseconds for A to reach router S. Node A will update the QoS-related information of a QOS_NLRI attribute, indicating that, to reach network 192.0.20.0, it takes 23 milliseconds. Router A will install this new route in its database, and will propagate the corresponding UPDATE message to its peers. On the other hand, router B is not capable of processing the information conveyed in the QOS_NLRI attribute, and it will therefore set the Partial bit of the QOS_NLRI attribute in the corresponding UPDATE message, leaving the one-way delay information detailed in both QoS Information Code and Sub-code unchanged. Upon receipt of the UPDATE message sent by router A, router E will update the one-way delay information since it is a QOS_NRLI-capable peer. Finally, router D receives the UPDATE message, and selects a Jacquenet Experimental - Expires August 2004 [Page 10]
Internet Draft The QOS_NLRI Attribute February 2004 route with a 40 milliseconds one-way delay to reach network 192.0.20.0, as depicted in figure 3. [Fig. 3: Selecting QoS Routes Across Domains.] This simulation result shows that the selection of a delay-inferred route over a BGP route may not yield an optimal decision. In the above example, the 40 ms-route goes through routers D-E-A-S, while a "truly optimal" BGP route would be through routers D-E-F-A-S, hence a 38 ms-route. This is because of a BGP4 rule that does not allow router F to send an UPDATE message towards router E, because router F received the UPDATE message from router A thanks to the iBGP connection it has established with A. 7.3. Additional Results The following table reflects the results obtained from a simulation network composed of 9 autonomous systems and 20 BGP peers. The numbers contained in the columns reflect the percentage of serviced requirements, where the requirements are expressed in terms of delay. Three parameters have been taken into account: - The percentage of BGP peers that have the ability to process the information conveyed in the QOS_NLRI attribute (denoted as "x% Q- BGP" in the following table), - The transit delays "observed" (and artificially simulated) on each transmission link: the higher the delays, the lower the percentage of serviced QoS requirements, - The QoS requirements themselves, expressed in terms of delay: as such, the strongest requirements (i.e. the lowest delays) have less chance to be satisfied. +-------------------------------------------+ | Delay | 0% Q-BGP | 50% Q-BGP | 100% Q-BGP | +-------------------------------------------+ | 3 | 11 | 8,3 | 11 | +-------------------------------------------+ | 5 | 30,5 | 30,5 | 36,1 | +-------------------------------------------+ | 6 | 40 | 47,2 | 55,5 | +-------------------------------------------+ | 7 | 47 | 59,7 | 72,2 | +-------------------------------------------+ | 8 | 62,5 | 79 | 91,6 | +-------------------------------------------+ | 9 | 63 | 84,7 | 97,2 | +-------------------------------------------+ | 10 | 70,8 | 90,2 | 98,6 | +-------------------------------------------+ Jacquenet Experimental - Expires August 2004 [Page 11]
Internet Draft The QOS_NLRI Attribute February 2004 | 11 | 76,3 | 93 | 98,6 | +-------------------------------------------+ | 12 | 86,1 | 97,2 | 100 | +-------------------------------------------+ | 13 | 88,8 | 98,6 | 100 | +-------------------------------------------+ | 14 | 94,4 | 100 | 100 | +-------------------------------------------+ | 15 | 94,4 | 100 | 100 | +-------------------------------------------+ | 16 | 94,4 | 100 | 100 | +-------------------------------------------+ | 17 | 97,2 | 100 | 100 | +-------------------------------------------+ | 18 | 98,6 | 100 | 100 | +-------------------------------------------+ | 19 | 98,6 | 100 | 100 | +-------------------------------------------+ | 20 | 98,6 | 100 | 100 | +-------------------------------------------+ | 21 | 98,6 | 100 | 100 | +-------------------------------------------+ | 22 | 100 | 100 | 100 | +-------------------------------------------+ This table clearly demonstrates the technical feasibility of the approach, and how the use of the QOS_NLRI attribute can improve the percentage of serviced QoS requirements. 7.4. Next Steps This simulation effort is currently pursued in order to better qualify the interest of using the BGP4 protocol to convey QoS-related information between domains, from a scalability perspective, i.e. the growth of BGP traffic vs. the stability of the network. The stability of the IP network is probably one of the most important aspects, since QoS-related information is subject to very dynamic changes, thus yielding non-negligible risks of flapping. 8. IANA Considerations Section 4 of this draft documents an optional transitive BGP-4 attribute named "QOS_NLRI" whose type value will be assigned by IANA. Section 5 of this draft also documents a Capability Code whose value should be assigned by IANA as well. 9. Security Considerations This additional BGP-4 attribute specification does not change the underlying security issues inherent in the existing BGP-4 protocol specification [14]. Jacquenet Experimental - Expires August 2004 [Page 12]
Internet Draft The QOS_NLRI Attribute February 2004 10. References [1] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [3] Rekhter, Y., Li T., "A Border Gateway Protocol 4 (BGP-4)", RFC 1771, March 1995. [4] Almes, G., Kalidindi, S., "A One-Way-Delay Metric for IPPM", RFC 2679, September 1999. [5] Demichelis, C., Chimento, P., "IP Packet Delay Variation Metric for IP Performance Metrics (IPPM)", RFC 3393, November 2002. [6] Nichols, K., Blake, S., Baker, F., Black, D., "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC 2474, December 1998. [7] Traina, P., McPherson, D., Scudder, J., "Autonomous System Confederations for BGP", RFC 3065, February 2001. [8] Jacquenet, C., "A COPS Client-Type for Traffic Engineering", draft-jacquenet-cops-te-00.txt, Work in Progress, February 2004. [9] Apostolopoulos, G. et al, "QoS Routing Mechanisms and OSPF Extensions", RFC 2676, August 1999. [10] Reynolds, J., Postel, J., "ASSIGNED NUMBERS", RFC 1700, October 1994. [11] Walton, D., et al., "Advertisement of Multiple Paths in BGP", draft-walton-bgp-add-paths-01.txt, Work in Progress, November 2002. [12] Chandra, R., Scudder, J., "Capabilities Advertisement with BGP- 4", RFC 3392, November 2002. [13] Narten, T., Alvestrand, H., "Guidelines for Writing an IANA Considerations Section in RFCs", RFC 2434, October 1998. [14] Heffernan, A., "Protection of BGP sessions via the TCP MD5 Signature Option", RFC 2385, August 1998. 11. Acknowledgments Part of this work is funded by the European Commission, within the context of the MESCAL (Management of End-to-End Quality of Service Across the Internet At Large, http://www.mescal.org) project, which is itself part of the IST (Information Society Technologies) research program. The author would also like to thank all the partners of the MESCAL project for the fruitful discussions that have been conducted within the context of the traffic engineering specification effort of the project, as well as O. Bonaventure and B. Carpenter for their valuable input. Jacquenet Experimental - Expires August 2004 [Page 13]
Internet Draft The QOS_NLRI Attribute February 2004 12. Authors' Addresses Geoffrey Cristallo Alcatel Francis Wellesplein, 1 2018 Antwerp Belgium Phone: +32 (0)3 240 7890 E-Mail: geoffrey.cristallo@alcatel.be Christian Jacquenet France Telecom 3, avenue Franois Chteau CS 36901 35069 Rennes Cedex France Phone: +33 2 99 87 63 31 Email: christian.jacquenet@francetelecom.com 13. Full Copyright Statement Copyright(C) The Internet Society (2004). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Jacquenet Experimental - Exp. August 2004 [Page 14]