BGP Extensions for Routing Policy Distribution (RPD)
draft-ietf-idr-rpd-07
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Active".
|
|
|---|---|---|---|
| Authors | Zhenbin Li , Liang Ou , Yujia Luo , Sujian Lu , Gyan Mishra , Huaimo Chen , Shunwan Zhuang , Haibo Wang | ||
| Last updated | 2020-08-03 (Latest revision 2020-07-31) | ||
| Replaces | draft-li-idr-flowspec-rpd | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | Susan Hares | ||
| Shepherd write-up | Show Last changed 2020-07-15 | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | Susan Hares <shares@ndzh.com> |
draft-ietf-idr-rpd-07
Network Working Group Z. Li
Internet-Draft Huawei
Intended status: Standards Track L. Ou
Expires: February 4, 2021 Y. Luo
China Telcom Co., Ltd.
S. Lu
Tencent
G. Mishra
Verizon Inc.
H. Chen
Futurewei
S. Zhuang
H. Wang
Huawei
August 3, 2020
BGP Extensions for Routing Policy Distribution (RPD)
draft-ietf-idr-rpd-07
Abstract
It is hard to adjust traffic and optimize traffic paths in a
traditional IP network from time to time through manual
configurations. It is desirable to have a mechanism for setting up
routing policies, which adjusts traffic and optimizes traffic paths
automatically. This document describes BGP Extensions for Routing
Policy Distribution (BGP RPD) to support this.
Requirements Language
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 [RFC2119] [RFC8174]
when, and only when, they appear in all capitals, as shown here.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
Li, et al. Expires February 4, 2021 [Page 1]
Internet-Draft BGP RPD August 2020
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 4, 2021.
Copyright Notice
Copyright (c) 2020 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
(https://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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Inbound Traffic Control . . . . . . . . . . . . . . . . . 4
3.2. Outbound Traffic Control . . . . . . . . . . . . . . . . 4
4. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 5
4.1. Using a New AFI and SAFI . . . . . . . . . . . . . . . . 5
4.2. BGP Wide Community and Atoms . . . . . . . . . . . . . . 6
4.2.1. RouteAttr TLV/sub-TLV . . . . . . . . . . . . . . . . 7
4.2.2. Sub-TLVs of the Parameters TLV . . . . . . . . . . . 10
4.3. Capability Negotiation . . . . . . . . . . . . . . . . . 12
5. Routing Policy Considerations . . . . . . . . . . . . . . . . 13
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 14
7. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
9.1. Existing Assignments . . . . . . . . . . . . . . . . . . 14
9.2. Routing Policy Type Registry . . . . . . . . . . . . . . 14
9.3. RouteAttr Atom Type . . . . . . . . . . . . . . . . . . . 15
9.4. Route Attributes Sub-TLV Registry . . . . . . . . . . . . 15
9.5. Attribute Change Sub-TLV Registry . . . . . . . . . . . . 16
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
10.1. Normative References . . . . . . . . . . . . . . . . . . 16
10.2. Informative References . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
Li, et al. Expires February 4, 2021 [Page 2]
Internet-Draft BGP RPD August 2020
1. Introduction
It is difficult to optimize traffic paths in a traditional IP network
because of the following:
o Heavy and error prone configuration. Traffic can only be adjusted
device by device. All routers that the traffic traverses need to
be configured. The configuration workload is heavy. The
operation is not only time consuming but also prone to
misconfiguration for Service Providers.
o Complex. The routing policies used to control network routes are
complex, posing difficulties to subsequent maintenance. High
maintenance skills are required.
It is desirable to have an automatic mechanism for setting up routing
policies, which can simplify routing policy configuration. This
document describes extensions to BGP for Routing Policy Distribution
to resolve these issues.
2. Terminology
The following terminology is used in this document.
o ACL: Access Control List
o BGP: Border Gateway Protocol [RFC4271]
o FS: Flow Specification
o NLRI: Network Layer Reachability Information [RFC4271]
o PBR: Policy-Based Routing
o RPD: Routing Policy Distribution
o VPN: Virtual Private Network
3. Problem Statement
Providers have the requirement to adjust their business traffic
routing policies from time to time because of the following:
o Business development or network failure introduces link congestion
and overload.
o Business changes or network additions produce unused resources
such as idle links.
Li, et al. Expires February 4, 2021 [Page 3]
Internet-Draft BGP RPD August 2020
o Network transmission quality is decreased as the result of delay,
loss and they need to adjust traffic to other paths.
o To control OPEX and CPEX, they may prefer the transit provider
with lower price.
3.1. Inbound Traffic Control
In Figure 1, for the reasons above, the provider P of AS100 may wish
the inbound traffic from AS200 to enter AS100 through link L3 instead
of the others. Since P doesn't have any administrative control over
AS200, there is no way for P to directly modify the route selection
criteria inside AS200.
Traffic from PE1 to Prefix1
----------------------------------->
+-----------------+ +-------------------------+
| +---------+ | L1 | +----+ +----------+|
| |Speaker1 | +------------+ |IGW1| |policy ||
| +---------+ |** L2**| +----+ |controller||
| | ** ** | +----------+|
| +---+ | **** | |
| |PE1| | **** | |
| +---+ | ** ** | |
| +---------+ |** L3**| +----+ |
| |Speaker2 | +------------+ |IGW2| AS100 |
| +---------+ | L4 | +----+ |
| | | |
| AS200 | | |
| | | ... |
| | | |
| +---------+ | | +----+ +-------+ |
| |Speakern | | | |IGWn| |Prefix1| |
| +---------+ | | +----+ +-------+ |
+-----------------+ +-------------------------+
Prefix1 advertised from AS100 to AS200
<----------------------------------------
Figure 1: Inbound Traffic Control case
3.2. Outbound Traffic Control
In Figure 2, the provider P of AS100 prefers link L3 for the traffic
to the destination Prefix2 among multiple exits and links to AS200.
This preference can be dynamic and might change frequently because of
Li, et al. Expires February 4, 2021 [Page 4]
Internet-Draft BGP RPD August 2020
the reasons above. So, provider P expects an efficient and
convenient solution.
Traffic from PE2 to Prefix2
----------------------------------->
+-------------------------+ +-----------------+
|+----------+ +----+ |L1 | +---------+ |
||policy | |IGW1| +------------+ |Speaker1 | |
||controller| +----+ |** **| +---------+ |
|+----------+ |L2** ** | +-------+|
| | **** | |Prefix2||
| | **** | +-------+|
| |L3** ** | |
| AS100 +----+ |** **| +---------+ |
| |IGW2| +------------+ |Speaker2 | |
| +----+ |L4 | +---------+ |
| | | |
|+---+ | | AS200 |
||PE2| ... | | |
|+---+ | | |
| +----+ | | +---------+ |
| |IGWn| | | |Speakern | |
| +----+ | | +---------+ |
+-------------------------+ +-----------------+
Prefix2 advertised from AS200 to AS100
<----------------------------------------
Figure 2: Outbound Traffic Control case
4. Protocol Extensions
This document specifies a solution using a new AFI and SAFI with the
BGP Wide Community for encoding a routing policy.
4.1. Using a New AFI and SAFI
A new AFI and SAFI are defined: the Routing Policy AFI whose
codepoint 16398 has been assigned by IANA, and SAFI whose codepoint
75 has been assigned by IANA.
The AFI and SAFI pair uses a new NLRI, which is defined as follows:
Li, et al. Expires February 4, 2021 [Page 5]
Internet-Draft BGP RPD August 2020
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
+-+-+-+-+-+-+-+-+
| NLRI Length |
+-+-+-+-+-+-+-+-+
| Policy Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Distinguisher (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peer IP (4/16 octets) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
NLRI Length: 1 octet represents the length of NLRI. If the Length
is anything other than 9 or 21, the NLRI is corrupt and the
enclosing UPDATE message is ignored.
Policy Type: 1 octet indicates the type of a policy. 1 is for
export policy. 2 is for import policy. If the Policy Type is any
other value, the NLRI is corrupt and the enclosing UPDATE message
is ignored.
Distinguisher: 4 octet value uniquely identifies the policy in the
peer.
Peer IP: 4/16 octet value indicates an IPv4/IPv6 peer.
The NLRI containing the Routing Policy is carried in MP_Reach_NLRI
and MP_UNREACH_NLRI path attributes in a BGP UPDATE message, which
MUST also contain the BGP mandatory attributes and MAY contain some
BGP optional attributes.
When receiving a BGP UPDATE message with routing policy, a BGP
speaker processes it only if the peer IP address in the NLRI is 0 or
the IP address of the BGP speaker.
The content of the Routing Policy is encoded in a BGP Wide Community.
4.2. BGP Wide Community and Atoms
The BGP wide community is defined in
[I-D.ietf-idr-wide-bgp-communities]. It can be used to facilitate
the delivery of new network services and be extended easily for
distributing different kinds of routing policies.
A wide community Atom is a TLV (or sub-TLV), which may be included in
a BGP wide community container (or BGP wide community for short)
Li, et al. Expires February 4, 2021 [Page 6]
Internet-Draft BGP RPD August 2020
containing some BGP Wide Community TLVs. Three BGP Wide Community
TLVs are defined in [I-D.ietf-idr-wide-bgp-communities], which are
BGP Wide Community Target(s) TLV, Exclude Target(s) TLV, and
Parameter(s) TLV. The value of each of these TLVs comprises a series
of Atoms, each of which is a TLV (or sub-TLV). A new wide community
Atom is defined for BGP Wide Community Target(s) TLV and a few new
Atoms are defined for BGP Wide Community Parameter(s) TLV. For your
reference, the format of the TLV is illustrated below:
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
+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value (variable) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Format of Wide Community Atom TLV
4.2.1. RouteAttr TLV/sub-TLV
A RouteAttr Atom TLV (or RouteAttr TLV/sub-TLV for short) is defined
and may be included in a Target TLV. 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (TBD1) | Length (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Format of RouteAttr Atom TLV
The Type for RouteAttr is TBD1. In RouteAttr TLV, four sub-TLVs are
defined: IPv4 Prefix, IPv6 Prefix, AS-Path, and Community sub-TLV.
An IP prefix sub-TLV gives matching criteria on IPv4 prefixes. Its
format is illustrated below:
Li, et al. Expires February 4, 2021 [Page 7]
Internet-Draft BGP RPD August 2020
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type 1 | Length (N x 8) |M-Type | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mask | GeMask | LeMask |M-Type | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mask | GeMask | LeMask |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Format of IPv4 Prefix sub-TLV
Type: 1 for IPv4 Prefix.
Length: N x 8, where N is the number of tuples <M-Type, Flags, IPv4
Address, Mask, GeMask, LeMask>. If Length is not a multiple of 8,
the Atom is corrupt and the enclosing UPDATE message MUST be
ignored.
M-Type: 4 bits for match types, four of which are defined:
M-Type = 0: Exact match.
M-Type = 1: Match prefix greater and equal to the given masks.
M-Type = 2: Match prefix less and equal to the given masks.
M-Type = 3: Match prefix within the range of the given masks.
Flags: 4 bits. No flags are currently defined.
IPv4 Address: 4 octets for an IPv4 address.
Mask: 1 octet for the mask length.
GeMask: 1 octet for match range, must be less than Mask or be 0.
LeMask: 1 octet for match range, must be greater than Mask or be 0.
For example, tuple <M-Type=0, Flags=0, IPv4 Address = 1.1.0.0, Mask =
22, GeMask = 0, LeMask = 0> represents an exact IP prefix match for
1.1.0.0/22.
Li, et al. Expires February 4, 2021 [Page 8]
Internet-Draft BGP RPD August 2020
<M-Type=1, Flags=0, IPv4 Address = 16.1.0.0, Mask = 24, GeMask = 24,
LeMask = 0> represents match IP prefix 1.1.0.0/24 greater-equal 24.
<M-Type=2, Flags=0, IPv4 Address = 17.1.0.0, Mask = 24, GeMask = 0,
LeMask = 26> represents match IP prefix 17.1.0.0/24 less-equal 26.
<M-Type=3, Flags=0, IPv4 Address = 18.1.0.0, Mask = 24, GeMask = 24,
LeMask = 32> represents match IP prefix 18.1.0.0/24 greater-equal to
24 and less-equal 32.
Similarly, an IPv6 Prefix sub-TLV represents match criteria on IPv6
prefixes. Its format is illustrated below:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type 4 | Length (N x 20) |M-Type | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 Address (16 octets) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mask | GeMask | LeMask |M-Type | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 Address (16 octets ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mask | GeMask | LeMask |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Format of IPv6 Prefix sub-TLV
An AS-Path sub-TLV represents a match criteria in a regular
expression string. Its format is illustrated below:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type 2 | Length (Variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS-Path Regex String |
: :
| ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Format of AS Path sub-TLV
Type: 2 for AS-Path.
Li, et al. Expires February 4, 2021 [Page 9]
Internet-Draft BGP RPD August 2020
Length: Variable, maximum is 1024.
AS-Path Regex String: AS-Path regular expression string.
A community sub-TLV represents a list of communities to be matched
all. Its format is illustrated below:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type 3 | Length (N x 4 + 1) | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Community 1 Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ . . . ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Community N Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Format of Community sub-TLV
Type: 3 for Community.
Length: N x 4 + 1, where N is the number of communities. If Length
is not a multiple of 4 plus 1, the Atom is corrupt and the
enclosing UPDATE MUST be ignored.
Flags: 1 octet. No flags are currently defined. These bits MUST be
sent as zero and ignored on receipt.
4.2.2. Sub-TLVs of the Parameters TLV
For the Parameter(s) TLV, two action sub-TLVs are defined: MED change
sub-TLV and AS-Path change sub-TLV. When the community in the
container is MATCH AND SET ATTR, the Parameter(s) TLV can include
these sub-TLVs. When the community is MATCH AND NOT ADVERTISE, the
Parameter(s) TLV's value is empty.
A MED change sub-TLV indicates an action to change the MED. Its
format is illustrated below:
Li, et al. Expires February 4, 2021 [Page 10]
Internet-Draft BGP RPD August 2020
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type 1 | Length (5) | OP |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Format of MED Change sub-TLV
Type: 1 for MED Change.
Length: 5. If Length is any other value, the sub-TLV is corrupt and
the enclosing UPDATE MUST be ignored.
OP: 1 octet. Three are defined:
OP = 0: assign the Value to the existing MED.
OP = 1: add the Value to the existing MED. If the sum is greater
than the maximum value for MED, assign the maximum value to
MED.
OP = 2: subtract the Value from the existing MED. If the
existing MED minus the Value is less than 0, assign 0 to MED.
If OP is any other value, the sub-TLV is ignored.
Value: 4 octets.
An AS-Path change sub-TLV indicates an action to change the AS-Path.
Its format is illustrated below:
Li, et al. Expires February 4, 2021 [Page 11]
Internet-Draft BGP RPD August 2020
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type 2 | Length (n x 5) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Count1 |
+-+-+-+-+-+-+-+-+
~ . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ASn |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Countn |
+-+-+-+-+-+-+-+-+
Format of AS-Path Change sub-TLV
Type: 2 for AS-Path Change.
Length: n x 5. If Length is not a multiple of 5, the sub-TLV is
corrupt and the enclosing UPDATE MUST be ignored.
ASi: 4 octet. An AS number.
Counti: 1 octet. ASi repeats Counti times.
The sequence of AS numbers are added to the existing AS Path.
4.3. Capability Negotiation
It is necessary to negotiate the capability to support BGP Extensions
for Routing Policy Distribution (RPD). The BGP RPD Capability is a
new BGP capability [RFC5492]. The Capability Code for this
capability is 72 assigned by the IANA. The Capability Length field
of this capability is variable. The Capability Value field consists
of one or more of the following tuples:
+--------------------------------------------------+
| Address Family Identifier (2 octets) |
+--------------------------------------------------+
| Subsequent Address Family Identifier (1 octet) |
+--------------------------------------------------+
| Send/Receive (1 octet) |
+--------------------------------------------------+
BGP RPD Capability
Li, et al. Expires February 4, 2021 [Page 12]
Internet-Draft BGP RPD August 2020
The meaning and use of the fields are as follows:
Address Family Identifier (AFI): This field is the same as the one
used in [RFC4760].
Subsequent Address Family Identifier (SAFI): This field is the same
as the one used in [RFC4760].
Send/Receive: This field indicates whether the sender is (a) willing
to receive Routing Policies from its peer (value 1), (b) would like
to send Routing Policies to its peer (value 2), or (c) both (value 3)
for the <AFI, SAFI>. If Send/Receive is any other value, that tuple
is ignored but any other tuples present are still used.
5. Routing Policy Considerations
Routing policies are used to filter routes and control how routes are
received and advertised. If route attributes, such as reachability,
are changed, the path along which network traffic passes changes
accordingly.
When advertising, receiving, and importing routes, the router
implements certain policies based on actual networking requirements
to filter routes and change the attributes of the routes. Routing
policies serve the following purposes:
o Control route advertising: Only routes that match the rules
specified in a policy are advertised.
o Control route receiving: Only the required and valid routes are
received. This reduces the size of the routing table and improves
network security.
o Filter and control imported routes: A routing protocol may import
routes discovered by other routing protocols. Only routes that
satisfy certain conditions are imported to meet the requirements
of the protocol.
o Modify attributes of specified routes Attributes of the routes:
that are filtered by a routing policy are modified to meet the
requirements of the local device.
o Configure fast reroute (FRR): If a backup next hop and a backup
outbound interface are configured for the routes that match a
routing policy, IP FRR, VPN FRR, and IP+VPN FRR can be
implemented.
Routing policies are implemented using the following procedures:
Li, et al. Expires February 4, 2021 [Page 13]
Internet-Draft BGP RPD August 2020
1. Define rules: Define features of routes to which routing policies
are applied. Users define a set of matching rules based on
different attributes of routes, such as the destination address
and the address of the router that advertises the routes.
2. Implement the rules: Apply the matching rules to routing policies
for advertising, receiving, and importing routes.
6. Contributors
The following people have substantially contributed to the definition
of the BGP-FS RPD and to the editing of this document:
Peng Zhou
Huawei
Email: Jewpon.zhou@huawei.com
7. Security Considerations
Protocol extensions defined in this document do not affect BGP
security other than as discussed in the Security Considerations
section of [RFC5575].
8. Acknowledgements
The authors would like to thank Acee Lindem, Jeff Haas, Jie Dong,
Lucy Yong, Qiandeng Liang, Zhenqiang Li, and Donald Eastlake for
their comments to this work.
9. IANA Considerations
9.1. Existing Assignments
IANA has assigned a new AFI of value 16398 from the registry "Address
Family Numbers" for Routing Policy.
IANA has assigned a new SAFI of value 75 from the registry
"Subsequent Address Family Identifiers (SAFI) Parameters" for Routing
Policy.
IANA has assigned a new Code Point of value 72 from the registry
"Capability Codes" for Routing Policy Distribution.
9.2. Routing Policy Type Registry
IANA is requested to create a new registry called "Routing Policy
Type". The allocation policy of this registry is "First Come First
Served (FCFS)".
Li, et al. Expires February 4, 2021 [Page 14]
Internet-Draft BGP RPD August 2020
The initial code points are as follows:
+-------------+-----------------------------------+-------------+
| Code Point | Description | Reference |
+-------------+-----------------------------------+-------------+
| 0 | Reserved | |
+-------------+-----------------------------------+-------------+
| 1 | Export Policy |This document|
+-------------+-----------------------------------+-------------+
| 2 | Import Policy |This document|
+-------------+-----------------------------------+-------------+
| 3 - 255 | Available | |
+-------------+-----------------------------------+-------------+
9.3. RouteAttr Atom Type
IANA is requested to assign a code-point from the registry "BGP
Community Container Atom Types" as follows:
+---------------------+------------------------------+-------------+
| TLV Code Point | Description | Reference |
+---------------------+------------------------------+-------------+
| TBD1 (48 suggested) | RouteAttr Atom |This document|
+---------------------+------------------------------+-------------+
9.4. Route Attributes Sub-TLV Registry
IANA is requested to create a new registry called "Route Attributes
Sub-TLV" under RouteAttr Atom TLV. The allocation policy of this
registry is "First Come First Served (FCFS)".
The initial code points are as follows:
+-------------+-----------------------------------+-------------+
| Code Point | Description | Reference |
+-------------+-----------------------------------+-------------+
| 0 | Reserved | |
+-------------+-----------------------------------+-------------+
| 1 | IPv4 Prefix Sub-TLV |This document|
+-------------+-----------------------------------+-------------+
| 2 | AS-Path Sub-TLV |This document|
+-------------+-----------------------------------+-------------+
| 3 | Community Sub-TLV |This document|
+-------------+-----------------------------------+-------------+
| 4 | IPv6 Prefix Sub-TLV |This document|
+-------------+-----------------------------------+-------------+
| 5 - 255 | Available | |
+-------------+-----------------------------------+-------------+
Li, et al. Expires February 4, 2021 [Page 15]
Internet-Draft BGP RPD August 2020
9.5. Attribute Change Sub-TLV Registry
IANA is requested to create a new registry called "Attribute Change
Sub-TLV" under Parameter(s) TLV. The allocation policy of this
registry is "First Come First Served (FCFS)".
Initial code points are as follows:
+-------------+-----------------------------------+-------------+
| Code Point | Description | Reference |
+-------------+-----------------------------------+-------------+
| 0 | Reserved | |
+-------------+-----------------------------------+-------------+
| 1 | MED Change Sub-TLV |This document|
+-------------+-----------------------------------+-------------+
| 2 | AS-Path Change Sub-TLV |This document|
+-------------+-----------------------------------+-------------+
| 3 - 255 | Available | |
+-------------+-----------------------------------+-------------+
10. References
10.1. Normative References
[I-D.ietf-idr-wide-bgp-communities]
Raszuk, R., Haas, J., Lange, A., Decraene, B., Amante, S.,
and P. Jakma, "BGP Community Container Attribute", draft-
ietf-idr-wide-bgp-communities-05 (work in progress), July
2018.
[RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities
Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,
<https://www.rfc-editor.org/info/rfc1997>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<https://www.rfc-editor.org/info/rfc4760>.
Li, et al. Expires February 4, 2021 [Page 16]
Internet-Draft BGP RPD August 2020
[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February
2009, <https://www.rfc-editor.org/info/rfc5492>.
[RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
and D. McPherson, "Dissemination of Flow Specification
Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009,
<https://www.rfc-editor.org/info/rfc5575>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
10.2. Informative References
[I-D.ietf-idr-registered-wide-bgp-communities]
Raszuk, R. and J. Haas, "Registered Wide BGP Community
Values", draft-ietf-idr-registered-wide-bgp-communities-02
(work in progress), May 2016.
Authors' Addresses
Zhenbin Li
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
Liang Ou
China Telcom Co., Ltd.
109 West Zhongshan Ave,Tianhe District
Guangzhou 510630
China
Email: ouliang@chinatelecom.cn
Li, et al. Expires February 4, 2021 [Page 17]
Internet-Draft BGP RPD August 2020
Yujia Luo
China Telcom Co., Ltd.
109 West Zhongshan Ave,Tianhe District
Guangzhou 510630
China
Email: luoyuj@sdu.edu.cn
Sujian Lu
Tencent
Tengyun Building,Tower A ,No. 397 Tianlin Road
Shanghai, Xuhui District 200233
China
Email: jasonlu@tencent.com
Gyan S. Mishra
Verizon Inc.
13101 Columbia Pike
Silver Spring MD 20904
USA
Phone: 301 502-1347
Email: gyan.s.mishra@verizon.com
Huaimo Chen
Futurewei
Boston, MA
USA
Email: Huaimo.chen@futurewei.com
Shunwan Zhuang
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: zhuangshunwan@huawei.com
Li, et al. Expires February 4, 2021 [Page 18]
Internet-Draft BGP RPD August 2020
Haibo Wang
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: rainsword.wang@huawei.com
Li, et al. Expires February 4, 2021 [Page 19]