Huawei's GRE Tunnel Bonding Protocol
draft-zhang-gre-tunnel-bonding-05
The information below is for an old version of the document that is already published as an RFC.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8157.
|
|
|---|---|---|---|
| Authors | Nicolai Leymann , Cornelius Heidemann , Mingui Zhang , Behcet Sarikaya , Margaret Cullen | ||
| Last updated | 2018-12-20 (Latest revision 2016-12-20) | ||
| RFC stream | Independent Submission | ||
| Intended RFC status | Informational | ||
| Formats | |||
| IETF conflict review | conflict-review-zhang-gre-tunnel-bonding | ||
| Stream | ISE state | Published RFC | |
| Consensus boilerplate | Unknown | ||
| Document shepherd | Eliot Lear | ||
| Shepherd write-up | Show Last changed 2017-01-11 | ||
| IESG | IESG state | Became RFC 8157 (Informational) | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | "Nevil Brownlee" <rfc-ise@rfc-editor.org> | ||
| IANA | IANA review state | IANA OK - Actions Needed | |
| IANA action state | RFC-Ed-Ack |
draft-zhang-gre-tunnel-bonding-05
Independent Submission N. Leymann
Internet Draft C. Heidemann
Intended Category: Informational Deutsche Telekom AG
M. Zhang
B. Sarikaya
Huawei
M. Cullen
Painless Security
Expires: June 24, 2017 December 21, 2016
Huawei's GRE Tunnel Bonding Protocol
draft-zhang-gre-tunnel-bonding-05.txt
Abstract
There is an emerging demand for solutions that provide redundancy and
load-sharing across wired and cellular links from a single service
provider, so that a single subscriber is provided with bonded access
to heterogeneous connections at the same time.
In this document, GRE (Generic Routing Encapsulation) Tunnel Bonding
is specified as an enabling approach for bonded access to a wired and
a wireless network in customer premises, e.g. homes. In GRE Tunnel
Bonding, two GRE tunnels, one per network connection, are set up and
bonded together to form a single GRE tunnel for a subscriber.
Compared with each composing connection, the bonded connections
promise increased access capacity and improved reliability. The
solution described in this document is currently implemented by
Huawei and deployed by Deutsche Telekom AG. Publication of this
document is to enable other developers to build interoperable
implementations.
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
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http://www.ietf.org/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
Copyright and License Notice
Copyright (c) 2016 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Acronyms and Terminology . . . . . . . . . . . . . . . . . . . 4
3. Use Case . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Control Plane . . . . . . . . . . . . . . . . . . . . . . . 7
4.2. Data Plane . . . . . . . . . . . . . . . . . . . . . . . . 7
4.3. Traffic Classification and Distribution . . . . . . . . . . 7
4.4. Traffic Recombination . . . . . . . . . . . . . . . . . . . 8
4.5. Bypass . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.6. Measurement . . . . . . . . . . . . . . . . . . . . . . . . 9
4.7. Policy Control Considerations . . . . . . . . . . . . . . . 9
5. Control Protocol Specification (Control Plane) . . . . . . . . 9
5.1. GRE Tunnel Setup Request . . . . . . . . . . . . . . . . . 11
5.1.1. Client Identification Name . . . . . . . . . . . . . . 12
5.1.2. Session ID . . . . . . . . . . . . . . . . . . . . . . 12
5.1.3. DSL Synchronization Rate . . . . . . . . . . . . . . . 13
5.2. GRE Tunnel Setup Accept . . . . . . . . . . . . . . . . . . 13
5.2.1. H IPv4 Address . . . . . . . . . . . . . . . . . . . . 14
5.2.2. H IPv6 Address . . . . . . . . . . . . . . . . . . . . 14
5.2.3. Session ID . . . . . . . . . . . . . . . . . . . . . . 15
5.2.4. RTT Difference Threshold . . . . . . . . . . . . . . . 15
5.2.5. Bypass Bandwidth Check Interval . . . . . . . . . . . . 16
5.2.6. Active Hello Interval . . . . . . . . . . . . . . . . . 16
5.2.7. Hello Retry Times . . . . . . . . . . . . . . . . . . . 17
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5.2.8. Idle Timeout . . . . . . . . . . . . . . . . . . . . . 17
5.2.9. Bonding Key Value . . . . . . . . . . . . . . . . . . . 18
5.2.10. Configured DSL Upstream Bandwidth . . . . . . . . . . 19
5.2.11. Configured DSL Downstream Bandwidth . . . . . . . . . 19
5.2.12. RTT Difference Threshold Violation . . . . . . . . . . 20
5.2.13. RTT Difference Threshold Compliance . . . . . . . . . 20
5.2.14. Idle Hello Interval . . . . . . . . . . . . . . . . . 21
5.2.15. No Traffic Monitored Interval . . . . . . . . . . . . 22
5.3. GRE Tunnel Setup Deny . . . . . . . . . . . . . . . . . . . 22
5.3.1. Error Code . . . . . . . . . . . . . . . . . . . . . . 22
5.4. GRE Tunnel Hello . . . . . . . . . . . . . . . . . . . . . 23
5.4.1. Timestamp . . . . . . . . . . . . . . . . . . . . . . . 23
5.4.2. IPv6 Prefix Assigned by HAAP . . . . . . . . . . . . . 24
5.5. GRE Tunnel Tear Down . . . . . . . . . . . . . . . . . . . 25
5.6. GRE Tunnel Notify . . . . . . . . . . . . . . . . . . . . . 25
5.6.1. Bypass Traffic Rate . . . . . . . . . . . . . . . . . . 25
5.6.2. Filter List Package . . . . . . . . . . . . . . . . . . 26
5.6.3. Switching to DSL Tunnel . . . . . . . . . . . . . . . . 29
5.6.4. Overflowing to LTE Tunnel . . . . . . . . . . . . . . . 29
5.6.5. DSL Link Failure . . . . . . . . . . . . . . . . . . . 30
5.6.6. LTE Link Failure . . . . . . . . . . . . . . . . . . . 30
5.6.7. IPv6 Prefix Assigned to Host . . . . . . . . . . . . . 30
5.6.8. Diagnostic Start: Bonding Tunnel . . . . . . . . . . . 31
5.6.9. Diagnostic Start: DSL Tunnel . . . . . . . . . . . . . 31
5.6.10. Diagnostic Start: LTE Tunnel . . . . . . . . . . . . . 32
5.6.11. Diagnostic End . . . . . . . . . . . . . . . . . . . . 32
5.6.12. Filter List Package ACK . . . . . . . . . . . . . . . 33
5.6.13. Switching to Active Hello State . . . . . . . . . . . 33
5.6.14. Switching to Idle Hello State . . . . . . . . . . . . 34
5.6.15. Tunnel Verification . . . . . . . . . . . . . . . . . 34
6. Tunnel Protocol Operation (Data Plane) . . . . . . . . . . . . 35
6.1. The GRE Header . . . . . . . . . . . . . . . . . . . . . . 36
6.2. Automatic Setup of GRE Tunnels . . . . . . . . . . . . . . 36
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 38
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 38
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 38
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 39
10.1. Normative References . . . . . . . . . . . . . . . . . . . 39
10.2. Informative References . . . . . . . . . . . . . . . . . . 40
Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 41
1. Introduction
Service providers used to provide subscribers with separate access to
their fixed networks and mobile networks. It has become desirable to
bond these heterogeneous networks together to offer access service to
subscribers that offer increased access capacity and improved
reliability.
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This document focuses on the use case that DSL (Digital Subscriber
Line) connection and LTE (Long Term Evolution) connection are bonded
together. When the traffic volume exceeds the bandwidth of the DSL
connection, the excess amount can be offloaded to the LTE connection.
Home Gateway (HG) is a Customer Premises Equipment (CPE) initiating
the DSL and LTE connections. Hybrid Access Aggregation Point (HAAP)
is the network function that resides in the provider's networks to
terminate these bonded connections. Note that if there were more than
two connections that need to be bonded, the GRE Tunnel Bonding
mechanism could support that scenario as well. However, support for
more than two connections is out the scope of this document. Also,
the protocol specified in this document is limited to the single-
operator scenario only, i.e., the two peering boxes, HG and HAAP, are
operated by a single provider. The adaptation of the GRE Tunnel
Bonding protocol to the multi-provider scenario is left as future
work.
This document bases the solution on GRE (Generic Routing
Encapsulation [RFC2874] [RFC2890]) since GRE is widely supported in
both fixed and mobile networks. Approaches specified in this document
might as well be used by other tunneling technologies to achieve
tunnel bonding. However, such kind of variants are out the scope of
this document.
For each heterogeneous connection (DSL and LTE) between the HG and
HAAP, one GRE tunnel is set up. HG and HAAP respectively serve as the
common termination point of the two tunnels at both end. Those GRE
tunnels are further bonded together to form a logical GRE tunnel for
the subscriber. HG conceals the composing GRE tunnels from the end
nodes, and end nodes simply treat the logical GRE tunnel as a single
IP link. This provides an overlay: the users' IP packets (inner IP)
are encapsulated in GRE which is in turn carried over IP (outer IP).
The GRE Tunnel Bonding Protocol is developed by Huawei and has been
deployed in networks operated by Deutsche Telekom AG. Publication of
this document is to make it open to the public and enable other
developers to build interoperable implementations.
2. Acronyms and Terminology
GRE: Generic Routing Encapsulation [RFC2874] [RFC2890]
DSL: Digital Subscriber Line is a family of technologies that are
used to transmit digital data over telephone lines
LTE: Long Term Evolution. A standard for wireless communication of
high-speed data for mobile phones and data terminals. Commonly
marketed as 4G LTE.
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HG: Home Gateway. A CPE device that is enhanced to support the
simultaneous use of both fixed broadband and 3GPP access connections.
HAAP: Hybrid Access Aggregation Point. A logical function in
Operator's network, terminating bonded connections while offering
high speed Internet.
CIR: Committed Information Rate [RFC2698]
RTT: Round Trip Time
AAA: Authentication, Authorization and Accounting [RFC6733]
SOAP: Simple Object Access Protocol. It is a protocol specification
for exchanging structured information in the implementation of web
services in computer networks.
FQDN: A Fully Qualified Domain Name (FQDN) is a domain name that
includes all higher level domains relevant to the entity named.
[RFC1594]
DSCP: The six-bit codepoint (DSCP) of the Differentiated Services
Field (DS Field) in the IPv4 and IPv6 Headers [RFC2724].
BRAS: Broadband Remote Access Server. It routes traffic to and from
broadband remote access devices such as Digital Subscriber Line
Access Multiplexers (DSLAM) on an Internet service provider's (ISP)
network.
PGW: Packet Data Network Gateway. In the Long Term Evolution (LTE)
architecture for the Evolved Packet Core (EPC), the PGW acts as an
anchor for user plane mobility.
PDP: Packet Data Protocol. A packet transfer protocol used in
wireless GPRS (General Packet Radio Service)/HSDPA (High Speed
Downlink Packet Access) networks.
PPPoE: Point-to-Point Protocol over Ethernet is a network protocol
for encapsulating PPP frames inside Ethernet frames.
DNS: Domain Name System is a hierarchical distributed naming system
for computers, services, or any resource connected to the Internet or
a private network.
DHCP: Dynamic Host Configuration Protocol. A standardized network
protocol used on Internet Protocol (IP) networks for dynamically
distributing network configuration parameters, such as IP addresses
for interfaces and services.
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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 [RFC2119].
3. Use Case
Bonding Connection
+-+ ****************************
| | *+-+ +-+*
| | *|E+-- LTE Connection --+ |*
subscriber |C| *+-+ |H|* Internet
| | *+-+ | |*
| | *|D+-- DSL Connection --+ |*
| | *+-+ +-+*
+-+ ****************************
\______/ \__/
HCPE HAAP
C: The service endpoint of the bonding service at the HG.
E: The endpoint of the LTE connection resides in HG.
D: The endpoint of the DSL connection resides in HG
H: The endpoint for each heterogeneous connection at HAAP.
Figure 3.1: Offloading from DSL to LTE, increased access capacity
If a Service Provider runs heterogeneous networks, such as fixed and
mobile, subscribers eager to use those networks simultaneously for
increased access capacity rather than just using a single network. As
shown by the reference model in Figure 3.1, the subscriber expects a
significantly higher access bandwidth from the bonding connection
than from the DSL connection. In other words, when the traffic volume
exceeds the bandwidth of the DSL connection, the excess amount may be
offloaded to the LTE connection.
Compared to per-flow load balancing mechanisms which are widely used
nowadays, the use case described in this document requires a per-
packet offloading approach. For per-flow load-balancing, the maximum
bandwidth that may be used by a traffic flow is the bandwidth of an
individual connection. While for per-packet offloading, a single flow
may use the added-up bandwidth of the two connections.
4. Overview
In this document, the widely supported GRE is chosen as the tunneling
technique. With the newly defined control protocol, GRE tunnels are
setup on top of the DSL and LTE connections which are ended at D and
H or E and H, as shown in Figure 3.1. These tunnels are bonded
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together to form a single logical bonding connection between HG and
HAAP. Subscribers use this logical connection without knowing the
composing GRE tunnels.
4.1. Control Plane
A clean-slate control protocol is designed to manage the GRE tunnels
that are setup per heterogeneous connection between HG and HAAP. The
goal is to design a compact control plane for bonding access instead
of reusing existing control planes.
In order to measure the performance of connections, control packets
need to co-route the same path with data packets. Therefore, a GRE
Channel is opened for the purpose of data plane forwarding of control
plane packets. As shown in Figure 5.1, the GRE header ([RFC2784])
with the Key extension specified by [RFC2890] is being used. The GRE
Protocol Type (0xB7EA) is used to identify this GRE Channel. A family
of control messages are encapsulated with GRE header and carried over
this channel. Attributes, formatted in Type-Length-Value style, are
further defined and included in each control message.
With the newly defined control plane, the GRE tunnels between HG and
HAAP can be established, managed and released without the involvement
of operators.
4.2. Data Plane
Using the control plane defined in Section 4.1, GRE tunnels can be
automatically setup per heterogeneous connection between the HG and
the HAAP. For the use case described in Section 3, one GRE tunnel is
ended at the DSL WAN interfaces, e.g., DSL GRE tunnel, and another
GRE tunnel is ended at the LTE WAN interfaces, e.g., LTE GRE tunnel.
Each tunnel may carry user's IP packets as payload, which forms a
typical IP-over-IP overlay. These tunnels are bonded together to
offer a single access point to subscribers.
As shown in Figure 6.1, the GRE header ([RFC2784]) with the Key and
Sequence Number extensions specified by [RFC2890] is used to
encapsulate data packets. The Protocol Type is either 0x0800
[RFC2784] or 0x86DD [RFC7676], which indicates the inner packet is
either an IPv4 packet or an IPv6 packet. The GRE Key field is set to
a unique value for the entire bonding connection. The GRE Sequence
Number field is used to maintain the sequence of packets transported
in all GRE tunnels as a single flow between the HG and the HAAP.
4.3. Traffic Classification and Distribution
For the offloading use case, the coloring mechanism specified in
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[RFC2697] is being used to classify subscriber's IP packets, both
upstream and downstream, into the DSL GRE tunnel or the LTE GRE
tunnel. Packets colored as green or yellow will be distributed into
the DSL GRE tunnel and packets colored as red will be distributed
into the LTE GRE tunnel. For the scenario that requires more than two
GRE tunnels, multiple levels of token buckets might be realized.
However, that is out of the scope for this document.
The Committed Information Rate (CIR) of the coloring mechanism is set
to the total DSL WAN bandwidth minus the bypass DSL bandwidth (See
Section 4.4.). The total DSL WAN bandwidth MAY be configured, MAY be
obtained from the management system (AAA server, SOAP server, etc.),
or MAY be detected in real-time using ANCP [RFC6320].
4.4. Traffic Recombination
For the offloading use case, the recombination function at the
receiver provides in-order delivery of subscribers' traffic. The
receiver maintains a small reordering buffer and orders the data
packets in this buffer by the Sequence Number field [RFC2890] of the
GRE header. All packets carried on GRE tunnels which belong to the
same bonding connection go into a single reordering buffer.
Operators may configure the maximum allowed size (See
MAX_PERFLOW_BUFFER in [RFC2890]) of the buffer for reordering. They
may also configure the maximum time (See OUTOFORDER_TIMER in
[RFC2890]) that a packet can stay in the buffer for reordering. The
OUTOFORDER_TIMER must be configured carefully. Values larger than the
difference of the normal Round-Trip Time (e.g., 100 ms) of the two
connections are not recommended. Implementation and deployment
experiences exhibits there is usually a large margin for the value of
MAX_PERFLOW_BUFFER. Values larger than the multiply of the sum of the
line rate of the two connections and the value of OUTOFORDER_TIMER
should be used.
4.5. Bypass
Service Providers provide some services that should not be delivered
over the bonding connection. For example, Service Providers may not
expect real-time IPTV to be carried by the LTE GRE tunnel. It is
required that IPTV traffic bypasses the GRE Tunnel Bonding and uses
the raw DSL bandwidth. Bypass traffic is not subject to the traffic
classification and distribution specified above. The raw connection
used for bypass traffic is not controlled by the HAAP. It may or may
not go through device that HAAP resides in.
The HAAP may announce the service types that need to bypass the
bonded GRE tunnels using the Filter List Package attribute as
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specified in Section 5.6.2. The HG and the HAAP need to set aside the
DSL bandwidth for bypassing. The available DSL bandwidth for GRE
Tunnel Bonding is equal to the total DSL bandwidth minus the bypass
bandwidth.
4.6. Measurement
Since control packets are routed using the same paths as the data
packets, the real performance of the data paths (e.g., the GRE
tunnels) can be measured. The GRE Tunnel Hello messages specified in
Section 5.3 are used to carry the timestamp information and the Round
Trip Time (RTT) value can therefore be calculated based on the
timestamp.
Besides the end-to-end delay of the GRE tunnels, the HG and the HAAP
need to measure the capacity of the tunnels as well. For example, the
HG is REQUIRED to measure the downstream bypassing bandwidth and
report it to the HAAP in real time (See Section 5.6.1.).
4.7. Policy Control Considerations
Operators and users may input policies into the GRE Tunnel Bonding.
These policies will be interpreted into parameters or actions that
impact the traffic classification, distribution, combination,
measurement and bypass.
Operators and users may offer the service types that need to bypass
the bonded GRE tunnels. Service types defined by operators will be
delivered from the HAAP to the HG through the control plane (See
Section 5.6.12.), and the HG will use the raw connection to transmit
traffic for these service types. Users may as well define bypass
service types on the HG. Bypass service types defined by users need
not to be delivered to the HAAP.
Operators may specify the interval for sending Hello messages and the
retry times for the HG or the HAAP to send out Hello messages before
the failure of a connection.
Since the GRE tunnels are setup on top of heterogeneous DSL and LTE
connections, if the difference of the transmission delays of these
connections exceeds a given threshold for a certain period, the HG
and the HAAP should be able to stop the offloading behavior and
fallback to a traditional transmission mode, where the LTE GRE tunnel
is disused while all traffic is transmitted over the DSL GRE tunnel.
Operators are allowed to define this threshold and period.
5. Control Protocol Specification (Control Plane)
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Control messages are used to establish, maintain, measure and tear
down GRE tunnels between the HG and the HAAP. Also, the control plane
undertakes the responsibility convey traffic policies over the GRE
tunnels.
For the purpose of measurement, control messages need to be delivered
as GRE encapsulated packets and co-routed with data plane packets.
The new GRE Protocol Type (0xB7EA) is allocated for this purpose and
the standard GRE header as per [RFC2874] with the Key extension
specified by [RFC2890] is used. The Checksum Present bit is set to
zero. Key Present bit is set to 1. The Sequence Number Present bit is
set to 0. So the format of the GRE header for control messages of the
GRE Tunnel Bonding protocol is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| |1|0| Reserved0 | Ver | Protocol Type 0xB7EA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Key
The Key field is used to carry a random number for the purpose of
security. The random number is generated by the HAAP and informed
to the HG. (See Section 5.2.9.)
The general format of the entire control message is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| |1|0| Reserved0 | Ver | Protocol Type 0xB7EA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|MsgType|T-Type | |
+-+-+-+-+-+-+-+-+ Attributes +
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5.1: The format of control messages of GRE Tunnel Bonding
MsgType (4 bits)
Message Type. The control message family contains the following 6
types of control messages:
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Control Message Family Type
========================== =========
GRE Tunnel Setup Request 1
GRE Tunnel Setup Accept 2
GRE Tunnel Setup Deny 3
GRE Tunnel Hello 4
GRE Tunnel Tear Down 5
GRE Tunnel Notify 6
Reserved 0,7-15
T-Type (4 bits)
Tunnel Type. Set to 0001 if the control message is sent via the
primary GRE tunnel (normally the DSL GRE tunnel). Set to 0010 if
the control message is sent via the secondary GRE tunnel (normally
the LTE GRE tunnel). Values 0000 and values from 0011 through 1111
are reserved for future use and MUST be ignored on receipt.
Attributes
The Attributes field includes the attributes that need to be
carried in the control message. Each Attribute has the following
format.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Value ~ (variable)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Attribute Type (1 octet)
The Attribute Type specifies the type of the attribute.
Attribute Length (2 octets)
Attribute Length indicates the length of the Attribute Value in
octets.
Attribute Value (variable)
The Attribute Value includes the value of the attribute.
All control messages are sent in network byte order (high order
octets first). Protocol Type carried in the GRE header for the
control message is 0xB7EA. Based on this number, the receiver will
determine to consume the GRE packet locally rather than further
forwarding.
5.1. GRE Tunnel Setup Request
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HG uses the GRE Tunnel Setup Request message to request that the HAAP
establish the GRE tunnels. It is sent out from HG's LTE and DSL WAN
interfaces separately. Attributes that need to be included in this
message are defined in the following subsections.
5.1.1. Client Identification Name
Operator uses the Client Identification Name (CIN) to identify the
HG. The HG sends the CIN to the HAAP for authentication and
authorization as specified in [TS23.401]. It is REQUIRED that the GRE
Tunnel Setup Request message sent out from the LTE WAN interface
contains the CIN attribute while the GRE Tunnel Setup Request message
sent out from the DSL WAN interface does not contain this attribute.
The CIN attribute has the following format:
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Client Identification Name (40 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
CIN, set to 3.
Attribute Length
Set to 40.
Client Identification Name
This is a 40-byte string value encoded in UTF-8 and set by the
operator. It is used as the identification of the HG in the
operator's network.
5.1.2. Session ID
This Session ID is generated by the HAAP when the LTE GRE Tunnel
Setup Request message is received. The HAAP announces the Session ID
to the HG in the LTE GRE Tunnel Setup Accept message. For those WAN
interfaces that need to be bonded together, the HG MUST use the same
Session ID. The HG MUST carry the Session ID attribute in each DSL
GRE Tunnel Setup Request message. For the first time that the LTE GRE
Tunnel Setup Request message is sent to the HAAP, the Session ID
attribute need not be included. However, if the LTE GRE Tunnel fails
and HG tries to revive it, the LTE GRE Tunnel Setup Request message
MUST include the Session ID attribute.
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The Session ID attribute has the following format:
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Session ID (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Session ID, set to 4.
Attribute Length
Set to 4.
Session ID
An unsigned integer generated by the HAAP. It is used as the
identification of bonded GRE Tunnels.
5.1.3. DSL Synchronization Rate
The HG uses the DSL Synchronization Rate to notify the HAAP about the
downstream bandwidth of the DSL link. The DSL GRE Tunnel Setup
Request message MUST include the DSL Synchronization Rate attribute.
The LTE GRE Tunnel Setup Request message SHOULD NOT include this
attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| DSL Synchronization Rate (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
DSL Synchronization Rate, set to 7.
Attribute Length
Set to 4.
DSL Synchronization Rate
An unsigned integer measured in kbps.
5.2. GRE Tunnel Setup Accept
The HAAP uses the GRE Tunnel Setup Accept message as the response to
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the GRE Tunnel Setup Request message. This message indicates
acceptance of the tunnel establishment and carries parameters of the
GRE tunnels. Attributes that need be to included in this message are
defined below.
5.2.1. H IPv4 Address
The HAAP uses the H IPv4 Address attribute to inform the HG of the H
IPv4 address. The HG uses the H IPv4 address as the destination
endpoint IPv4 address of the GRE tunnels (the source endpoint IPv4
addresses of the GRE tunnels are respectively DSL/LTE WAN interface
IP address (D/E)). The LTE GRE Tunnel Setup Accept message MUST
include the H IPv4 Address attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| H IPv4 Address (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
H IPv4 Address, set to 1.
Attribute Length
Set to 4.
H IPv4 Address
Set to the pre-configured IPv4 address (e.g. an IP address of a
Line Card in the HAAP) which is used as the endpoint IP address of
GRE tunnels by the HAAP.
5.2.2. H IPv6 Address
HAAP uses the H IPv6 Address attribute to inform the HG of the H IPv6
address. The HG uses the H IPv6 address as the destination endpoint
IPv6 address of the GRE tunnels (the source endpoint IPv4 addresses
of the GRE tunnels are respectively DSL/LTE WAN interface IP address
(D/E)). The LTE GRE Tunnel Setup Accept message MUST include the H
IPv6 Address attribute.
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+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| H IPv6 Address (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
H IPv6 Address, set to 1.
Attribute Length
Set to 16.
H IPv6 Address
Set to the pre-configured IPv6 address (e.g. an IP address of a
Line Card in the HAAP) which is used as the endpoint IP address of
GRE tunnels by HAAP.
5.2.3. Session ID
The LTE GRE Tunnel Setup Accept message MUST include Session ID
attribute as defined in Section 5.1.2.
5.2.4. RTT Difference Threshold
The HAAP uses the RTT Difference Threshold attribute to inform the HG
of the acceptable threshold of RTT difference between the DSL link
and the LTE link. If the measured RTT difference exceeds this
threshold, the HG SHOULD stop offloading traffic to the LTE GRE
tunnel. The LTE GRE Tunnel Setup Accept message MUST include the RTT
Difference Threshold attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| RTT Difference Threshold (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
RTT Difference Threshold, set to 9.
Attribute Length
Set to 4.
RTT Difference Threshold
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An unsigned integer measured in milliseconds. This value can be
chosen in the range 0 through 1000.
5.2.5. Bypass Bandwidth Check Interval
The HAAP uses the Bypass Bandwidth Check Interval attribute to inform
the HG of how frequently the bypass bandwidth should be checked. The
HG should check the bypass bandwidth of the DSL WAN interface in each
time period indicated by this interval. The LTE GRE Tunnel Setup
Accept message MUST include the Bypass Bandwidth Check Interval
attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Bypass Bandwidth Check Interval (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Bypass Bandwidth Check Interval, set to 10.
Attribute Length
Set to 4.
Bypass Bandwidth Check Interval
An unsigned integer measured in seconds. This value can be chosen
in the range 10 through 300.
5.2.6. Active Hello Interval
The HAAP uses the Active Hello Interval attribute to inform the HG of
the pre-configured interval for sending out GRE Tunnel Hellos. The HG
should send out GRE Tunnel Hellos via both the DSL and LTE WAN
interfaces in each time period as indicated by this interval. The LTE
GRE Tunnel Setup Accept message MUST include the Active Hello
Interval attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Active Hello Interval (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
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Active Hello Interval, set to 14.
Attribute Length
Set to 4.
Active Hello Interval
An unsigned integer measured in seconds. This value can be chosen
in the range 1 through 100.
5.2.7. Hello Retry Times
The HAAP uses the Hello Retry Times attribute to inform the HG of the
retry times for sending GRE Tunnel Hellos. If the HG does not receive
any acknowledgement from the HAAP for the number of GRE Tunnel Hello
attempts specified in this attribute, the HG will declare a failure
of the GRE Tunnel. The LTE GRE Tunnel Setup Accept message MUST
include the Hello Retry Times attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Hello Retry Times (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Hello Retry Times, set to 15.
Attribute Length
Set to 4.
Hello Retry Times
An unsigned integer, which takes values in the range 3 through 10.
5.2.8. Idle Timeout
The HAAP uses the Idle Timeout attribute to inform the HG of the pre-
configured timeout value to terminate the DSL GRE tunnel. When an LTE
GRE Tunnel failure is detected, all traffic will be sent over the DSL
GRE tunnel. If the failure of the LTE GRE tunnel lasts longer than
the Idle Timeout, subsequent traffic will be sent over raw DSL rather
than over a tunnel, and the DSL GRE tunnel SHOULD be terminated. The
LTE Tunnel Setup Accept message MUST include the Idle Timeout
attribute.
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+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Idle Timeout (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Idle Timeout, set to 16.
Attribute Length
Set to 4.
Idle Timeout
An unsigned integer measured in seconds. It takes values in the
range 0 through 172,800 with the granularity of 60. The default
value is 1,440 (24 hours). The value 0 indicates the idle timer
never expires.
5.2.9. Bonding Key Value
The HAAP uses the Bonding Key Value attribute to inform the HG of the
number which is to carried as the Key of the GRE header for
subsequent control messages. The Bonding Key Value is generated by
the HAAP and used for the purpose of security.
The method used to generate this number is up to implementations. The
Pseudo Random Number Generator defined in ANSI X9.31 Appendix A.2.4
is RECOMMENDED. Note that Random Number Generation collision is
allowed in the GRE Tunnel Bonding protocol.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Bonding Key Value (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Bonding Key Value, set to 20.
Attribute Length
Set to 4.
Bonding Key Value
A 32-bit random number generated by the HAAP.
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5.2.10. Configured DSL Upstream Bandwidth
The HAAP obtains the upstream bandwidth of the DSL link from the
management system and uses the Configured DSL Upstream Bandwidth
attribute to inform the HG. The HG uses the received upstream
bandwidth as the Committed Information Rate for the DSL link
[RFC2697]. The DSL GRE Tunnel Setup Accept message MUST include the
Configured DSL Upstream Bandwidth attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Configured DSL Upstream Bandwidth (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Configured DSL Upstream Bandwidth, set to 22.
Attribute Length
Set to 4.
Configured DSL Upstream Bandwidth
An unsigned integer measured in kbps.
5.2.11. Configured DSL Downstream Bandwidth
The HAAP obtains the downstream bandwidth of the DSL link from the
management system and uses the Configured DSL Downstream Bandwidth
attribute to inform the HG. The HG uses the received downstream
bandwidth as the base in calculating the bypassing bandwidth. The DSL
GRE Tunnel Setup Accept message MUST include the Configured DSL
Downstream Bandwidth attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
|Configured DSL Downstream Bandwidth(4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Configured DSL Downstream Bandwidth, set to 23.
Attribute Length
Set to 4.
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Configured DSL Downstream Bandwidth
An unsigned integer measured in kbps.
5.2.12. RTT Difference Threshold Violation
The HAAP uses the RTT Difference Threshold Violation attribute to
inform the HG of the number of times in a row that the RTT Difference
Threshold (See Section 5.2.4.) may be violated before the HG MUST
stop using the LTE GRE Tunnel. If the RTT Difference Threshold is
continuously violated for more than the indicated number of
measurements, the HG MUST stop using the LTE GRE tunnel. The LTE GRE
Tunnel Setup Accept message MUST include the RTT Difference Threshold
Violation attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| RTT Diff Threshold Violation (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
RTT Difference Threshold Violation, set to 24.
Attribute Length
Set to 4.
RTT Difference Threshold Violation
An unsigned integer which takes values in the range 1 through 25.
A typical value is 3.
5.2.13. RTT Difference Threshold Compliance
The HAAP uses the RTT Difference Threshold Compliance attribute to
inform the HG of the number of times in a row the RTT Difference
Threshold (See Section 5.2.4.) must be compliant before use of the
LTE GRE tunnel can be resumed. If the RTT Difference Threshold is
continuously detected to be compliant across more than this number of
measurments, the HG MAY resume using the LTE GRE tunnel. The LTE GRE
Tunnel Setup Accept message MUST include the RTT Difference Threshold
Compliance attribute.
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+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| RTT Diff Threshold Compliance (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
RTT Diff Threshold Compliance, set to 25.
Attribute Length
Set to 4.
RTT Diff Threshold Compliance
An unsigned integer which takes values in the range 1 through 25.
A typical value is 3.
5.2.14. Idle Hello Interval
The HAAP uses the Idle Hello Interval attribute to inform the HG of
the pre-configured interval for sending out GRE Tunnel Hellos when
the subscriber is detected to be idle. The HG SHOULD begin to send
out GRE Tunnel Hellos via both the DSL and LTE WAN interfaces in each
time period as indicated by this interval, if the bonded tunnels have
seen no traffic longer than the "No Traffic Monitored Interval" (See
Section 5.2.15.). The LTE GRE Tunnel Setup Accept message MUST
include the Idle Hello Interval attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Idle Hello Interval (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Idle Hello Interval, set to 31.
Attribute Length
Set to 4.
Idle Hello Interval
An unsigned integer measured in seconds. This value can be chosen
from the range 100 through 86,400 (24 hours) with the granularity
of 100. The default value is 1800 (30 minutes).
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5.2.15. No Traffic Monitored Interval
The HAAP uses the No Traffic Monitored Interval attribute to inform
the HG of the pre-configured interval for switching the GRE Tunnel
Hello mode. If traffic is detected on the bonded GRE tunnels before
this informed interval expires, the HG SHOULD switch to the Active
Hello Interval. The LTE GRE Tunnel Setup Accept message MUST include
the No Traffic Monitored Interval attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| No Traffic Monitored Interval (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
No Traffic Monitored Interval, set to 32.
Attribute Length
Set to 4.
No Traffic Monitored Interval
An unsigned integer measured in seconds. This value is in the
range 30 through 86,400 (24 hours). The default value is 60.
5.3. GRE Tunnel Setup Deny
HAAP MUST sends the GRE Tunnel Setup Deny message to HG if the GRE
tunnel setup request from this HG is denied. The HG MUST terminate
the GRE tunnel setup process as soon as it receives the GRE Tunnel
Setup Deny message.
5.3.1. Error Code
The HAAP uses the Error Code attribute to inform the HG of the error
code. The error code depicts the reason why the GRE tunnel setup
request is denied. Both the LTE GRE Tunnel Setup Deny message and the
DSL GRE Tunnel Setup Deny message MUST include the Error Code
attribute.
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+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Error Code (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Error Code, set to 17.
Attribute Length
Set to 4.
Error Code
An unsigned integer. The list of the codes are listed as follows.
1: The HAAP was not reachable over LTE during the GRE tunnel setup
request.
2: The HAAP was not reachable via DSL during the GRE tunnel setup
request.
3: The LTE GRE tunnel to the HAAP failed.
4: The DSL GRE tunnel to the HAAP failed.
5: The given DSL User ID is not allowed to use the GRE Tunnel
Bonding service.
6: The given User Alias (TOID)/User ID (GUID) is not allowed to
use the GRE Tunnel Bonding service.
7: The LTE and DSL User IDs do not match.
8: The HAAP denied the GRE tunnel setup request because a bonding
session with the same User ID already exists.
9: The HAAP denied the GRE tunnel setup request because the user's
CIN is not permitted.
10: The HAAP terminated a GRE Tunnel Bonding session for
maintenance reasons.
11: There was a communication error between the HAAP and the
management system during the LTE tunnel setup request.
12: There was a communication error between the HAAP and
management system during the DSL tunnel setup request.
5.4. GRE Tunnel Hello
After the DSL/LTE GRE tunnel is established, the HG begins to
periodically send out GRE Tunnel Hello messages via the tunnel, which
the HAAP acknowledges by returning GRE Tunnel Hello messages back to
the HG. This continues until the tunnel is terminated.
5.4.1. Timestamp
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The HAAP uses the Timestamp attribute to inform the HG of the
timestamp value that is used for RTT calculation. Both the LTE GRE
Tunnel Hello message and DSL GRE Tunnel Hello message MUST include
the Timestamp attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Timestamp (8 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Timestamp, set to 5.
Attribute Length
Set to 8.
Timestamp
The time since the system restarts. The high-order 4 octets
indicate an unsigned integer in units of one second; the low-order
4 octets indicate an unsigned integer in unit of one millisecond.
5.4.2. IPv6 Prefix Assigned by HAAP
The HAAP uses the IPv6 Prefix Assigned by the HAAP attribute to
inform the HG of the assigned IPv6 prefix. This IPv6 prefix is to be
captured by the Lawful Interception. Both the LTE GRE Tunnel Hello
message and the DSL GRE Tunnel Hello message MUST include the IPv6
Prefix Assigned by HAAP attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| IPv6 Prefix Assigned by HAAP (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
IPv6 Prefix Assigned by HAAP, set to 13.
Attribute Length
Set to 17.
IPv6 Prefix Assigned by HAAP
The highest-order 16 octets encode an IPv6 address. The lowest-
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order one octet encodes the prefix length. These two values are
put together to represent an IPv6 prefix.
5.5. GRE Tunnel Tear Down
The HAAP can terminate a DSL/LTE GRE tunnel by sending the GRE Tunnel
Tear Down message to the HG via the tunnel. The Error Code attribute
as defined in Section 5.3.1 MUST be included in this message. After
receiving the GRE Tunnel Tear Down message, the HG removes the IP
address of H which is the destination IP addresses of the DSL and LTE
GRE tunnels.
5.6. GRE Tunnel Notify
The HG and the HAAP use the GRE Tunnel Notify message which is
transmitted either through the DSL GRE tunnel or LTE GRE tunnel to
notify each other about their status regarding the DSL/LTE GRE
tunnels, the information for the bonded tunnels, the actions that
need to be taken, etc.
Usually, the receiver just sends the received attributes back as the
acknowledgement for each GRE Tunnel Notify message. There is an
exception for the Filter List Package. Since the size of the Filter
List Package attribute can be very large, a special attribute is
specified in Section 5.6.12 as the acknowledgement.
Attributes that need be to included in the GRE Tunnel Notify message
are defined below.
5.6.1. Bypass Traffic Rate
There are a few types of traffic that need to transmitted over the
raw DSL WAN interface rather than the bonded GRE tunnels. The HG has
to set aside bypass bandwidth on the DSL WAN interface for these
traffic types. Therefore, the available bandwidth of the DSL GRE
tunnel is the entire DSL WAN interface bandwidth minus the occupied
bypass bandwidth.
The HG uses the Bypass Traffic Rate attribute to inform the HAAP of
the downstream bypass bandwidth for the DSL WAN interface. The Bypass
Traffic Rate attribute will be included in the DSL GRE Tunnel Notify
message. The HAAP calculates the available downstream bandwidth for
the DSL GRE tunnel as the Configured DSL Downstream Bandwidth minus
this informed bypass bandwidth. The available DSL bandwidth will be
used as the Committed Information Rate (CIR) of the coloring system
[RFC2697].
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+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Bypass Traffic Rate (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Bypass Traffic Rate, set to 6.
Attribute Length
Set to 4.
Bypass Traffic Rate
An unsigned integer measured in kbps.
5.6.2. Filter List Package
The HAAP uses the Filter List Package attribute to inform the HG of
the service types that need to bypass the bonded GRE tunnels. The
full list of all filter items may be given by a series of Filter List
Package attributes with each specifying a partial list. At the HG, a
full list of filter items is maintained. Also, the HG needs to
maintain an exception list of filter items. For example, the packets
carrying the control messages defined in this document should be
excluded from the filter list.
Incoming packets that match a filter item in the filter list while
not matching any item in the exception list MUST be transmitted over
the raw DSL rather than the bonded GRE tunnels. Both the LTE GRE
Tunnel Notify message and GRE Tunnel Notify message MAY include the
Filter List Package attribute. The DSL GRE Tunnel Notify message is
preferred.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Filter List TLV (variable) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Filter List Package, set to 8.
Attribute Length
The total length of the Filter List TLV. The maximum allowed
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length is 969 bytes.
Filter List TLV
The Filter List TLV occurs one time in a Filter List Package
attribute. It has the following format.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Commit_Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packet_Sum | Packet_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Filter Item (1) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ...... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Filter Item (n) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where each filter item is of the following format
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enable | Description Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Description Value ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Value ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Commit_Count
An unsigned integer which identifies the version of the filter
item list. The version is shared by all Filter List Packages
and monotonic increasing by one for each new filter item list.
HG MUST refresh its filter item list when a new Commit_Count is
received.
Packet_Sum
If a single Filter List Package attribute might make the
control message larger than the MTU, fragmentation is used. The
Packet_Sum indicates the total number of fragments.
Packet_ID
The fragmentation index for this Filter List Package attribute.
Each fragment is numbered starting at 1 and increasing by one
up to Packet_Sum.
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Type
The Type of the Filter Item. Currently, the following types are
supported.
Filter Items Type
========================= ============
FQDN [RFC1594] 1
DSCP [RFC2724] 2
Destination Port 3
Destination IP 4
Destination IP&Port 5
Source Port 6
Source IP 7
Source IP&Port 8
Source Mac 9
Protocol 10
Source IP Range 11
Destination IP Range 12
Source IP Range&Port 13
Destination IP Range&Port 14
Other values are reserved for future use and MUST be ignored on
receipt.
Length
The length of the Filter Item in octets. Type and Length are
excluded.
Enable
Whether the filter item is enabled. One means enabled and zero
means disabled. Other possible values are reserved and MUST be
ignored on receipt.
Description Length
The length of the Description Value in octets.
Description Value
A variable string value encoded in UTF-8 that describes the
Filter List TLV (e.g., "FQDN").
Value
A variable string encoded in UTF-8 that specifies the value of
the Filter Item (e.g. "www.yahoo.com"). As an example, Type = 1
and Value = "www.yahoo.com" means that packets whose FQDN field
equals "www.yahoo.com" match the filter item. Values for "Mac"
are specified using hexadecimal numbers. Port number are
decimals as assigned by IANA in [Port-NO]. For the "Protocol"
type, the value could either be a decimal or a keyword
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specified by IANA in [Pro-NO]. The formats for "IP" and "IP
Range" are defined in [RFC4632] and [RFC4291] for IPv4 and IPv6
respectively. When the filter item is a combination of two
parameters (Type 5, 8 and 13), values for the two parameters
are separated by a colon (":").
5.6.3. Switching to DSL Tunnel
If the RTT difference is continuously detected to violate the RTT
Difference Threshold (See Section 5.2.4.) more than the times
specified in the RTT Difference Threshold Violation (See Section
5.2.12.), the HG uses the Switching to DSL Tunnel attribute to inform
the HAAP to use the DSL GRE tunnel only. When the HAAP receives this
attribute, it MUST begin to transmit downstream traffic to this HG
solely over the DSL GRE tunnel. The DSL GRE Tunnel Notify message MAY
include the Switching to DSL Tunnel attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Attribute Type
Switching to DSL Tunnel, set to 11.
Attribute Length
Set to 0.
5.6.4. Overflowing to LTE Tunnel
If the RTT difference is continuously detected to not violated the
RTT Difference Threshold attribute (See Section 5.2.4.) more than the
number of times specified in the RTT Difference Compliance attribute
(See Section 5.2.13), the HG uses the Overflowing to LTE Tunnel
attribute to inform HAAP that LTE GRE tunnel can be used again. The
DSL GRE Tunnel Notify message MAY include the Overflowing to LTE
Tunnel attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Attribute Type
Overflowing to LTE Tunnel, set to 12.
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Attribute Length
Set to 0.
5.6.5. DSL Link Failure
When the HG detects the DSL WAN interface status is down, it MUST
tear down the DSL GRE tunnel. It informs HAAP about the failure using
the DSL Link Failure attribute. The HAAP MUST tear down the DSL GRE
tunnel upon the DSL Link Failure attribute is received. The DSL Link
Failure attribute SHOULD be carried in the LTE GRE Tunnel Notify
message.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Attribute Type
DSL Link Failure, set to 18.
Attribute Length
Set to 0.
5.6.6. LTE Link Failure
When the HG detects the LTE WAN interface status is down, it MUST
tear down the LTE GRE tunnel. It informs the HAAP about the failure
using the LTE Link Failure attribute. HAAP MUST tear down the LTE GRE
tunnel upon the LTE Link Failure attribute is received. The LTE Link
Failure attribute SHOULD be carried in the DSL GRE Tunnel Notify
message.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Attribute Type
LTE Link Failure, set to 19.
Attribute Length
Set to 0.
5.6.7. IPv6 Prefix Assigned to Host
If the HG changes the IPv6 prefix assigned to the host, it uses the
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IPv6 Prefix Assigned to Host attribute to inform the HAAP. Both the
LTE GRE Tunnel Notify message and the DSL GRE Tunnel Notify message
MAY include the IPv6 Prefix Assigned to Host attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| IPv6 Prefix Assigned to Host (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
IPv6 Prefix Assigned to Host, set to 21.
Attribute Length
Set to 17.
IPv6 Prefix Assigned to Host
The highest-order 16 octets encode an IPv6 address. The lowest-
order one octet encodes the prefix length. These two values are
put together to represent an IPv6 prefix.
5.6.8. Diagnostic Start: Bonding Tunnel
The HG uses the Diagnostic Start: Bonding Tunnel attribute to inform
the HAAP to switch to diagnostic mode to test the performance of the
entire bonding tunnel. The Diagnostic Start: Bonding Tunnel attribute
SHOULD be carried in the DSL GRE Tunnel Notify message.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Attribute Type
Diagnostic Start: Bonding Tunnel, set to 26.
Attribute Length
Set to 0.
5.6.9. Diagnostic Start: DSL Tunnel
The HG uses the Diagnostic Start: DSL Tunnel attribute to inform the
HAAP to switch to diagnostic mode to test the performance of the DSL
GRE tunnel. The Diagnostic Start: DSL Tunnel attribute SHOULD be
carried in the DSL GRE Tunnel Notify message.
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+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Attribute Type
Diagnostic Start: DSL Tunnel, set to 27.
Attribute Length
Set to 0.
5.6.10. Diagnostic Start: LTE Tunnel
The HG uses the Diagnostic Start: LTE Tunnel attribute to inform the
HAAP to switch to diagnostic mode to test the performance of the
entire bonding tunnel. The Diagnostic Start: LTE Tunnel attribute
SHOULD be carried in the DSL GRE Tunnel Notify message.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Attribute Type
Diagnostic Start: LTE Tunnel, set to 18.
Attribute Length
Set to 0.
5.6.11. Diagnostic End
The HG uses the Diagnostic End attribute to inform th HAAP to stop
operating in diagnostic mode. The Diagnostic End attribute SHOULD be
carried in the DSL GRE Tunnel Notify message.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Attribute Type
Diagnostic End, set to 29.
Attribute Length
Set to 0.
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5.6.12. Filter List Package ACK
The HG uses the Filter List Package ACK attribute to acknowledge the
Filter List Package sent by the HAAP. Both the LTE GRE Tunnel Notify
message and the DSL GRE Tunnel Notify message MAY include the Filter
List Package ACK attribute.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+
| Filter List Package ACK (5 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+
Attribute Type
Filter List Package ACK, set to 30.
Attribute Length
Set to 5.
Filter List Package ACK
The highest-order 4 octets are the Commit_Count as defined in
Section 5.6.2. The lowest-order 1 octet encodes the following
error codes:
0: The Filter List Package is acknowledged.
1: The Filter List Package is not acknowledged. The HG is a new
subscriber and has not ever received a Filter List Package. In
this case, the HAAP SHOULD tear down the bonding tunnels and
force the HG to re-establish the GRE Tunnels.
2: The Filter List Package is not acknowledged. The HG has already
got a valid Filter List Package. The filter list on the HG will
continue to be used while HAAP need to do nothing.
5.6.13. Switching to Active Hello State
If traffic is being sent/received over the bonding GRE tunnels before
the "No Traffic Monitored Interval" expires (See Section 5.2.15.),
the HG sends to the HAAP a GRE Tunnel Notify message containing the
Switching to Active Hello State attribute.
The HAAP will switch to active hello state and send the HG a GRE
Tunnel Notify message carrying the Switching to Active Hello State
attribute as the ACK.
When the HG receives the ACK, it will switch to active hello state,
start RTT detection and start sending GRE Tunnel Hello messages with
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the Active Hello Interval (See Section 5.2.6.).
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Attribute Type
Switching to Active Hello State, set to 33.
Attribute Length
Set to 0.
5.6.14. Switching to Idle Hello State
The HG initiates switching to idle hello state when the bonding of
GRE Tunnels is successfully established and the LTE GRE Tunnel Setup
Accept message carrying the Idle Hello Interval attribute (See
Section 5.2.14.) is received. The HG sends the HAAP a GRE Tunnel
Notify message containing the Switching to Idle Hello State
attribute.
The HAAP will switch to idle hello state, clear RTT state and send
the HG a GRE Tunnel Notify message carrying the Switching to Idle
Hello State attribute as the ACK.
When the HG receives the ACK, it will switch to idle hello state,
stop RTT detection, clear RTT state as well and start sending GRE
Tunnel Hello messages with the Idle Hello Interval (See Section
5.2.14).
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Attribute Type
Switching to Idle Hello State, set to 34.
Attribute Length
Set to 0.
5.6.15. Tunnel Verification
The HAAP uses the Tunnel Verification attribute to inform the HG to
verify whether an existing LTE GRE tunnel is still functioning. The
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Tunnel Verification attribute SHOULD be carried in the LTE GRE Tunnel
Notify message. It provides a means to detect the tunnel faster than
the GRE Tunnel Hello, especially when the LTE GRE tunnel is in the
Idle Hello state and it takes much longer time to detect this
tunnel.
When the HAAP receives an LTE GRE Tunnel Setup Request and finds the
requested tunnel is conflicting with an existing tunnel, the HAAP
initiates the Tunnel Verification. The HAAP drops all conflicting LTE
GRE Tunnel Setup Request messages and sends GRE Tunnel Notify
messages carrying the Tunnel Verification attribute until the
verification ends. The HG MUST respond to the HAAP with the same
Tunnel Verification attribute as the ACK if the tunnel is still
functioning.
If the ACK of the Tunnel Verification attribute is received from the
HG, the HAAP judges that the existing tunnel is still functioning. An
LTE GRE Tunnel Deny message (with Error Code = 8) will be sent to the
HG. The HG SHOULD terminate the GRE tunnel setup request process
immediately.
If the HAAP does not receive a Tunnel Verification ACK message after
3 attempts (1 initial attempt and 2 retries), it will regard the
existing tunnel as failed and the LTE GRE Tunnel Setup Request will
be accepted.
+-+-+-+-+-+-+-+-+
|Attribute Type | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Attribute Type
Tunnel Verification, set to 35.
Attribute Length
Set to 0.
6. Tunnel Protocol Operation (Data Plane)
GRE tunnels are set up over heterogeneous connections, such as LTE
and DSL, between the HG and the HAAP. Users' IP (inner) packets are
encapsulated in GRE packets which in turn are carried in IP (outer)
packets. The general structure of data packets of the GRE Tunnel
Bonding protocol is shown as below.
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+--------------------------------+
| Media Header |
+--------------------------------+
| Outer IP Header |
+--------------------------------+
| GRE Header |
+--------------------------------+
| Inner IP Packet |
+--------------------------------+
6.1. The GRE Header
The GRE header is first standardized in [RFC2784]. [RFC2890] adds the
optional Key and Sequence Number fields.
The Checksum and the Reserved1 fields are not used in the GRE Tunnel
Bonding, therefore the C bit is set to zero.
The Key bit is set to one so that the Key field is present. The Key
field is used as a 32-bit random number. It is generated by the HAAP
per bonding connection and notified to HG (See Section 5.2.9).
The S bit is set to one, and the Sequence Number field is present and
used for in-order delivery as per [RFC2890].
The Protocol Type field in the GRE header MUST be set to 0x0800 for
IPv4 or 0x86DD for IPv6. So the GRE header used by data packets of
the GRE Tunnel Bonding protocol have the following format.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| |1|1| Reserved0 | Ver | Protocol Type 0x0800/86DD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6.1 The GRE header for data packets of GRE Tunnel Bonding
6.2. Automatic Setup of GRE Tunnels
The HG gets the DSL WAN interface IP address (D) from the Broadband
Remote Access Server (BRAS) via Point-to-Point Protocol over Ethernet
(PPPoE), and gets the LTE WAN interface IP address (E) through Packet
Data Protocol (PDP) from the Packet Data Network Gateway (PGW). The
domain name of a HAAP group may be configured or obtained via the
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DSL/LTE WAN interface based on gateway configuration protocols such
as [TR-069], where the HAAP group comprises of one or multiple HAAPs.
The Domain Name System (DNS) resolution of the HAAP group's domain
name is requested via the DSL/LTE WAN interface. The DNS server will
reply with an anycast HAAP IP address (G) which MAY be pre-configured
by the operator.
After the interface IP addresses have been acquired, the HG starts
the following GRE Tunnel Bonding procedure. It is REQUIRED that the
HG first set up the LTE GRE tunnel and then set up the DSL GRE
tunnel.
The HG sends the GRE Tunnel Setup Request message to the HAAP via the
LTE WAN interface. The outer source IP address for this message is
the LTE WAN interface IP address (E) while the outer destination IP
address is the anycast HAAP IP address (G). The HAAP with the highest
priority (e.g., the one that the HG has the least cost path to reach)
in the HAAP group, which receives the GRE Tunnel Setup Request
message, will initiate the Authentication and Authorization
procedure, as specified in [TS23.401], to check whether the HG is
trusted by the PGW.
If the Authentication and Authorization succeed, the HAAP sets the
LTE WAN interface IP address (E) which is obtained from the GRE
Tunnel Setup Request message (i.e., its outer source IP address) as
the destination endpoint IP address of the GRE tunnel and replies to
the HG's LTE WAN interface with the GRE Tunnel Setup Accept message
in which an IP address (H) of the HAAP (e.g. an IP address of a Line
Card in the HAAP) and a Session ID randomly generated by the HAAP are
carried as attributes. The outer source IP address for this message
is the IP address (H) or the anycast HAAP IP address (G) while the
outer destination IP address is the LTE WAN interface IP address (E).
Otherwise, the HAAP MUST send to the HG's LTE WAN interface the GRE
Tunnel Setup Deny message and the HG MUST terminate the tunnel set up
process once it receives the GRE Tunnel Setup Deny message.
After the LTE GRE tunnel is successfully set up, the HG will obtain
the C address over the tunnel from the HAAP through Dynamic Host
Configuration Protocol (DHCP). After that, the HG starts to set up
the DSL GRE tunnel. It sends a GRE Tunnel Setup Request message via
the DSL WAN interface, carrying the aforementioned Session ID
received from the HAAP. The outer source IP address for this message
is the DSL WAN interface IP address (D) while the outer destination
IP address is the IP address (H) of the HAAP. The HAAP, which
receives the GRE Tunnel Setup Request message, will initiate the
Authentication and Authorization procedure in order to check whether
the HG is trusted by the BRAS.
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If the Authentication and Authorization succeed, the HAAP sets the
DSL WAN interface IP address (D) which is obtained from the GRE
Tunnel Setup Request message (i.e., its outer source IP address) as
the destination endpoint IP address of the GRE tunnel and replies to
the HG's DSL WAN interface with the GRE Tunnel Setup Accept message.
The outer source IP address for this message is the IP address (H) of
the HAAP while the outer destination IP address is the DSL WAN
interface IP address (D). In this way, the two tunnels with the same
Session ID can be used to carry traffic from the same user. That is
to say, the two tunnels are "bonded" together. Otherwise, if the
Authentication and Authorization fail, the HAAP MUST send to the HG's
DSL WAN interface the GRE Tunnel Setup Deny message. Meanwhile, it
MUST send to the HG's LTE WAN interface the GRE Tunnel Tear Down
message. The HG MUST terminate the tunnel set up process once it
receives the GRE Tunnel Setup Deny message and MUST tear down the LTE
GRE tunnel that has been set up once it receives the GRE Tunnel Tear
Down Message.
7. Security Considerations
Malicious devices controlled by attackers may intercept the control
messages sent on the GRE tunnels. Later on, the rogue devices may
fake control messages to disrupt the GRE tunnels or attract traffic
of the target HG.
As a security feature, the Key field of the GRE header of the control
messages and the data packets is generated as a 32-bit clear-text
password, except the first GRE Setup Request message per bonding
connection sent from HG to HAAP, whose Key field is filled with all
zeros. HAAP and HG validate the Key value and the outer source IP
address and discard packets with any invalid combination.
Moreover, GRE over IP Security (IPSec) could be used to enhance the
security.
8. IANA Considerations
IANA need not to assign anything for the GRE Tunnel Bonding Protocol.
The GRE Protocol Type for the GRE Channel is set to 0xB7EA which is
under the control of IEEE Registration Authority. However, IANA may
update the "IEEE 802 Numbers" IANA web page [802Type] which is of
primarily historic interest.
9. Contributors
Li Xue
Individual
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EMail: xueli_jas@163.com
Zhongwen Jiang
Huawei Technologies
EMail: jiangzhongwen@huawei.com
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI
10.17487/RFC2119, March 1997, <http://www.rfc-
editor.org/info/rfc2119>.
[RFC2697] Heinanen, J. and R. Guerin, "A Single Rate Three Color
Marker", RFC 2697, DOI 10.17487/RFC2697, September 1999,
<http://www.rfc-editor.org/info/rfc2697>.
[RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. Traina,
"Generic Routing Encapsulation (GRE)", RFC 2784, DOI
10.17487/RFC2784, March 2000, <http://www.rfc-
editor.org/info/rfc2784>.
[RFC2890] Dommety, G., "Key and Sequence Number Extensions to GRE",
RFC 2890, DOI 10.17487/RFC2890, September 2000,
<http://www.rfc-editor.org/info/rfc2890>.
[TR-069] Broadband Forum, "CPE WAN Management Protocol", Issue: 1
Amendment 5, Nov, 2013, <https://www.broadband-
forum.org/technical/download/TR-069_Amendment-5.pdf>
[TS23.401] "3GPP TS23.401, General Packet Radio Service (GPRS)
enhancements for Evolved Universal Terrestrial Radio Access
Network (E-UTRAN) access", September 2013.
[Port-NO] IANA, "Service Name and Transport Protocol Port Number
Registry", <http://www.iana.org/assignments/service-names-
port-numbers>
[Pro-NO] IANA, "Assigned Internet Protocol Numbers",
<http://www.iana.org/assignments/protocol-numbers>
[RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing
(CIDR): The Internet Address Assignment and Aggregation
Plan", BCP 122, RFC 4632, DOI 10.17487/RFC4632, August
2006, <http://www.rfc-editor.org/info/rfc4632>.
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[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <http://www.rfc-editor.org/info/rfc4291>.
10.2. Informative References
[RFC1594] Marine, A., Reynolds, J., and G. Malkin, "FYI on Questions
and Answers - Answers to Commonly asked "New Internet User"
Questions", RFC 1594, March 1994.
[RFC2724] Handelman, S., Stibler, S., Brownlee, N., and G. Ruth,
"RTFM: New Attributes for Traffic Flow Measurement", RFC
2724, DOI 10.17487/RFC2724, October 1999, <http://www.rfc-
editor.org/info/rfc2724>.
[RFC6320] Wadhwa, S., Moisand, J., Haag, T., Voigt, N., and T.
Taylor, Ed., "Protocol for Access Node Control Mechanism in
Broadband Networks", RFC 6320, DOI 10.17487/RFC6320,
October 2011, <http://www.rfc-editor.org/info/rfc6320>.
[RFC6733] Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn,
Ed., "Diameter Base Protocol", RFC 6733, DOI
10.17487/RFC6733, October 2012, <http://www.rfc-
editor.org/info/rfc6733>.
[RFC7676] Pignataro, C., Bonica, R., and S. Krishnan, "IPv6 Support
for Generic Routing Encapsulation (GRE)", RFC 7676, DOI
10.17487/RFC7676, October 2015, <http://www.rfc-
editor.org/info/rfc7676>.
[802Type] IANA, "IEEE 802 Numbers",
<http://www.iana.org/assignments/ieee-802-numbers>.
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Author's Addresses
Nicolai Leymann
Deutsche Telekom AG
Winterfeldtstrasse 21-27
Berlin 10781
Germany
Phone: +49-170-2275345
Email: n.leymann@telekom.de
Cornelius Heidemann
Deutsche Telekom AG
Heinrich-Hertz-Strasse 3-7
Darmstadt 64295
Germany
Phone: +4961515812721
Email: heidemannc@telekom.de
Mingui Zhang
Huawei Technologies
No.156 Beiqing Rd. Haidian District,
Beijing 100095 P.R. China
EMail: zhangmingui@huawei.com
Behcet Sarikaya
Huawei USA
5340 Legacy Dr. Building 3
Plano, TX 75024
EMail: sarikaya@ieee.org
Margaret Cullen
Painless Security
14 Summer St. Suite 202
Malden, MA 02148 USA
EMail: margaret@painless-security.com
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