LSR Working Group L. Gong
Internet Draft China Mobile
Intended status: Standards Track C. Lin
Expires: August 18, 2025 M. Chen
New H3C Technologies
K. Talaulikar
L. Ginsberg
P. Psenak
Cisco Systems
February 18, 2025
Advertisement of Remote Interface Identifiers for Layer 2 Bundle
Members
draft-glctgp-lsr-l2-bundle-member-remote-id-02
Abstract
In networks where Layer 2 (L2) interface bundles (such as a Link
Aggregation Group (LAG) [IEEE802.1AX]) are deployed, a controller
may need to collect the connectivity relationships between bundle
members for traffic engineering (TE) purposes. For example, when
performing topology management and bidirectional path computation
for TE, it is essential to know the connectivity relationships among
bundle members.
This document describes how OSPF and IS-IS would advertise the
remote interface identifiers for Layer 2 bundle members. The
corresponding extension of BGP-LS is also specified.
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
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reference material or to cite them other than as "work in progress."
This Internet-Draft will expire on 18 August 2025.
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Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction...................................................2
1.1. Requirements Language.....................................3
2. Use Case.......................................................3
3. Advertising L2 Bundle Member Remote Interface Identifier.......4
4. OSPF Extension.................................................5
5. IS-IS Extension................................................5
6. BGP-LS Extension...............................................6
7. Acquirement of Remote Interface Identifier.....................7
8. Security Considerations........................................7
9. IANA Considerations............................................8
10. References....................................................8
10.1. Normative References.....................................8
10.2. Informational References................................10
Authors' Addresses...............................................10
1. Introduction
BGP-LS [RFC9552] is widely used for collecting topology information
from IGPs. In networks where Layer 2 (L2) interface bundles (such as
a Link Aggregation Group (LAG) [IEEE802.1AX]) are deployed, a
controller may need to collect the connectivity relationships
between bundle members for traffic engineering (TE) purposes. For
example, when performing topology management and bidirectional path
computation for TE, it is essential to know the connectivity
relationships among bundle members.
When advertising L2 bundles in OSPF [RFC9356] and IS-IS [RFC8668], a
member link is described by its local interface identifier, also
referred to as a link local identifier. If the remote interface
identifier could be advertised for each member link, the pairing
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relationships between the local and remote interfaces would be
clear.
This document describes the mechanism for advertising the remote
interface identifier for Layer 2 bundle members in OSPF and IS-IS.
The BGP-LS extension for advertising L2 bundle member interface
remote identifier is also specified in this document.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Use Case
Figure 1 shows a network, in which an L2 bundle is deployed between
R1 and R2. The controller collects the topology information from R3
via BGP-LS.
+----------+ BGP-LS
|Controller|<********************
+----------+ *
*
*
*
+----+ L2-Bundle +----+ +----+
| | /-------member 1-------\ | | | |
| | / \ | | | |
| R1 +----------member 2----------+ R2 +---+ R3 +
| | \ / | | | |
| | \-------member 3-------/ | | | |
+----+ +----+ +----+
Figure 1
The network operator may want to control bidirectional traffic flows
on the individual member links of the underlying Layer 2 bundle for
TE purposes. The real-time bandwidth, delay, and link loss might be
measured for each bundle member at both ends. Labels or SIDs might
be allocated for each bundle member at both ends. So, there would be
requirements for the controller to figure out the connectivity
relationships between bundle members.
This document defines a mechanism for IGP routers to advertise the
remote interface identifiers for each L2 bundle member, along with
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the corresponding mechanism for the controller to collect such
information via BGP-LS.
3. Advertising L2 Bundle Member Remote Interface Identifier
In OSPF, the remote interface identifiers of L2 bundle members are
advertised as follows.
OSPFv2 Extended Link TLV, or OSPFv3 Router-Link TLV, for L3 Link:
L2 Bundle Member Attributes TLV:
L2 Bundle Member Descriptor of Member #1
L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional -
as defined in Section 4)
L2 Bundle Member Attributes TLV:
L2 Bundle Member Descriptor of Member #2
L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional -
as defined in Section 4)
...
L2 Bundle Member Attributes TLV:
L2 Bundle Member Descriptor of Member #n
L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional -
as defined in Section 4)
In IS-IS, the remote interface identifiers of L2 bundle members are
advertised as follows. Note that IS-IS can advertise a set of
members in a single L2 Bundle Member Attribute Descriptor, so the L2
Bundle Member Interface Remote Identifier Sub-TLV MUST carry
multiple remote interface identifiers, one for each of the bundle
members advertised in the associated L2 Bundle Member Descriptor.
L2 Bundle Member Attributes TLV:
Parent L3 Neighbor Descriptor
Length of L2 Bundle Attribute Descriptor
Number of L2 Bundle Member Descriptors
L2 Bundle Member Link Local Identifiers of Member #1,#2,...,#n
Sub-TLV(s)
L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional -
as defined in Section 5) for Member #1,#2,...,#n
In BGP-LS, the remote interface identifiers of L2 bundle members are
advertised as follows.
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BGP-LS Link NLRI: Peer Adj Link for R1->R2(as described in Section
5.2 of [RFC9086])
Link Attributes:
L2 Bundle Member Attributes TLV:
L2 Bundle Member Descriptor of Member #1
L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional -
as defined in Section 6)
L2 Bundle Member Attributes TLV:
L2 Bundle Member Descriptor of Member #2
L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional -
as defined in Section 6)
...
L2 Bundle Member Attributes TLV:
L2 Bundle Member Descriptor of Member #n
L2 Bundle Member Interface Remote Identifier Sub-TLV (Optional -
as defined in Section 6)
4. OSPF Extension
This document defines a new L2 Bundle Member Interface Remote
Identifier Sub-TLV in both OSPFv2 and OSPFv3. This Sub-TLV is used
to advertise the remote interface identifier for a L2 bundle member.
It can be carried as a sub-TLV of the OSPF L2 Bundle Member
Attributes TLV [RFC9356]. 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 (TBA) | Length (4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: TBA.
o Length: 4.
o Remote Interface ID: Remote identifier of interface, 4 octets.
A remote interface ID with value of zero is not valid and MUST be
ignored and handled as if the sub-TLV was not present.
5. IS-IS Extension
This document defines a new L2 Bundle Member Interface Remote
Identifier Sub-TLV in IS-IS. This Sub-TLV is used to advertise the
remote interface identifiers for L2 bundle members.
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It can be carried as a sub-TLV of the IS-IS L2 Bundle Member
Attributes TLV [RFC8668]. 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 (TBA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote Interface ID 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote Interface ID N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: TBA.
o Length: 4 * Number of L2 Bundle Member Descriptors.
o Remote Interface ID: Remote identifier of interface, 4 octets.
There MUST be one Remote Interface ID for each of the L2 Bundle
Members advertised under the associated L2 Bundle Member Attribute
Descriptor. A remote interface ID with value of zero MUST be ignored
and handled as if the value was unknown.
6. BGP-LS Extension
This document defines a new L2 Bundle Member Interface Remote
Identifier Sub-TLV in BGP-LS. This Sub-TLV is derived from the
Remote Interface Identifier Sub-TLV of OSPF (Section 3) and IS-IS
(Section 4).
It can be carried as a sub-TLV of the BGP-LS L2 Bundle Member
Attributes TLV [RFC9085]. 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 (TBA) | Length (4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: TBA.
o Length: 4.
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o Remote Interface ID: Remote identifier of interface, 4 octets.
A remote interface ID with value of zero is not valid and MUST be
ignored and handled as if the sub-TLV was not present.
7. Acquirement of Remote Interface Identifier
IGPs have no direct way to exchange L2 bundle member link
identifiers since the Layer 3 protocol is not operating directly on
the bundle members. Some L2 protocols may be used to get the remote
interface identifiers for bundle members. This may be discovered via
[IEEE802.1AX] when used to form the LAG bundle. A router may also
run LLDP [802.1AB] on the bundle members to exchange local interface
identifiers with its neighbor, by using the LLDP Management Address
TLV.
How the remote interface identifier is obtained is out of the scope
of this document.
8. Security Considerations
This document describes how OSPF, IS-IS and BGP-LS would advertise
the remote interface identifiers for Layer 2 bundle members. There
are no new security issues introduced by the extensions in this
document. The security considerations of [RFC8668], [RFC9356] ,
[RFC9552],[RFC9085] and [RFC9086] are are applicable to this
document.
As always, if the IS-IS protocol is used in an environment where
unauthorized access to the physical links on which IS-IS Protocol
Data Units (PDUs) are sent occurs, then attacks are possible. The
use of authentication as defined in [RFC5304] and [RFC5310] is
recommended to prevent such attacks.
As always, if the OSPF protocol is used in an environment where
unauthorized access to the physical links on which OSPF packets are
sent occurs, then attacks are possible. The use of authentication
as defined in [RFC5709], [RFC7474], [RFC4552], and [RFC7166] is
recommended for preventing such attacks.
The isolation of BGP-LS peering sessions is recommended to ensure
that BGP-LS topology information (including the newly added remote
interface identifiers information) is not advertised to an external
BGP peering session outside the trusted domain [RFC8402].
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9. IANA Considerations
This document adds the following new sub-TLV to the "OSPFv2 Extended
Link TLV Sub-TLVs" registry.
+------+----------------------------------------------+----+
| Type | Designation |L2BM|
+======+==============================================+====+
| TBA | L2 Bundle Member Interface Remote Identifier | Y |
+------+----------------------------------------------+----+
This document adds the following new sub-TLV to the "OSPFv3
Extended-LSA Sub-TLVs" registry.
+------+----------------------------------------------+----+
| Type | Description |L2BM|
+======+==============================================+====+
| TBA | L2 Bundle Member Interface Remote Identifier | Y |
+------+----------------------------------------------+----+
This document adds the following new sub-TLV to the "IS-IS Sub-TLVs
for TLVs Advertising Neighbor Information" registry.
+------+-----------------------------+---+---+---+---+---+---+
| Type | Description | 22| 23| 25|141|222|223|
+======+=============================+===+===+===+===+===+===+
| TBA | L2 Bundle Member | n | n | y | n | n | n |
| | Interface Remote Identifier | | | | | | |
+------+-----------------------------+---+---+---+---+---+---+
This document adds the following new sub-TLV to the "BGP-LS NLRI and
Attribute TLVs" registry.
+------+----------------------------------------------+
| Type | Description |
+======+==============================================+
| TBA | L2 Bundle Member Interface Remote Identifier |
+------+----------------------------------------------+
10. References
10.1. Normative References
[IEEE802.1AX]
IEEE, "IEEE Standard for Local and Metropolitan Area
Networks--Link Aggregation", IEEE Std 802.1AX, DOI
10.1109/IEEESTD.2020.9105034, May 2020,
<https://doi.org/10.1109/IEEESTD.2020.9105034>.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality
for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006,
<https://www.rfc-editor.org/info/rfc4552>.
[RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic
Authentication", RFC 5304, DOI 10.17487/RFC5304, October
2008, <https://www.rfc-editor.org/info/rfc5304>.
[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic
Authentication", RFC 5310, DOI 10.17487/RFC5310, February
2009, <https://www.rfc-editor.org/info/rfc5310>.
[RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M.,
Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic
Authentication", RFC 5709, DOI 10.17487/RFC5709, October
2009, <https://www.rfc-editor.org/info/rfc5709>.
[RFC7166] Bhatia, M., Manral, V., and A. Lindem, "Supporting
Authentication Trailer for OSPFv3", RFC 7166,DOI
10.17487/RFC7166, March 2014, <https://www.rfc-
editor.org/info/rfc7166>.
[RFC7474] Bhatia, M., Hartman, S., Zhang, D., and A. Lindem, Ed.,
"Security Extension for OSPFv2 When Using Manual Key
Management", RFC 7474, DOI 10.17487/RFC7474, April 2015,
<https://www.rfc-editor.org/info/rfc7474>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, May 2017.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8668] Ginsberg, L., Ed., Bashandy, A., Filsfils, C., Nanduri,
M., and E. Aries, "Advertising Layer 2 Bundle Member Link
Attributes in IS-IS", RFC 8668, DOI 10.17487/RFC8668,
December 2019, <https://www.rfc-editor.org/info/rfc8668>.
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[RFC9085] Previdi, S., Talaulikar, K., Ed., Filsfils, C., Gredler,
H., and M. Chen, "Border Gateway Protocol - Link State
(BGP-LS) Extensions for Segment Routing", RFC 9085, DOI
10.17487/RFC9085, August 2021, <https://www.rfc-
editor.org/info/rfc9085>.
[RFC9086] Previdi, S., Talaulikar, K., Ed., Filsfils, C., Patel, K.,
Ray, S., and J. Dong, "Border Gateway Protocol - Link
State (BGP-LS) Extensions for Segment Routing BGP Egress
Peer Engineering", RFC 9086, DOI 10.17487/RFC9086, August
2021, <https://www.rfc-editor.org/info/rfc9086>.
[RFC9356] Talaulikar, K. and P. Psenak, "Advertising L2 Bundle
Member Link Attributes in OSPF", RFC 9356, January 2023,
<https://www.rfc-editor.org/info/rfc9356>.
10.2. Informational References
[802.1AB] "IEEE Standard for Local and metropolitan area networks-
Station and Media Access Control Connectivity Discovery",
IEEE Std 802.1AB-2016, 29 January 2016.
[RFC9552] Talaulikar, K., Ed., "Distribution of Link-State and
Traffic Engineering Information Using BGP", RFC 9552, DOI
10.17487/RFC9552, December 2023, <https://www.rfc-
editor.org/info/rfc9552>.
Authors' Addresses
Liyan Gong
China Mobile
China
Email: gongliyan@chinamobile.com
Changwang Lin
New H3C Technologies
China
Email: linchangwang.04414@h3c.com
Mengxiao Chen
New H3C Technologies
China
Email: chen.mengxiao@h3c.com
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Ketan Talaulikar
Cisco Systems
India
Email: ketant.ietf@gmail.com
Les Ginsberg
Cisco Systems
United States of America
Email: ginsberg@cisco.com
Peter Psenak
Cisco Systems
Apollo Business Center
Mlynske nivy 43
Bratislava 821 09
Slovakia
Email: ppsenak@cisco.com
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