Internet DRAFT - draft-ietf-lsvr-applicability
draft-ietf-lsvr-applicability
LSVR K. Patel
Internet-Draft Arrcus, Inc.
Intended status: Informational A. Lindem
Expires: 15 August 2024 LabN Consulting, L.L.C.
S. Zandi
G. Dawra
Linkedin
12 February 2024
Usage and Applicability of Link State Vector Routing in Data Centers
draft-ietf-lsvr-applicability-11
Abstract
This document discusses the usage and applicability of Link State
Vector Routing (LSVR) extensions in data center networks utilizing
CLOS or Fat-Tree topologies. The document is intended to provide a
simplified guide for the deployment of LSVR extensions.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 15 August 2024.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Recommended Reading . . . . . . . . . . . . . . . . . . . . . 3
4. Common Deployment Scenario . . . . . . . . . . . . . . . . . 3
5. Justification for BGP SPF Extension . . . . . . . . . . . . . 4
6. LSVR Applicability to CLOS Networks . . . . . . . . . . . . . 5
6.1. Usage of BGP-LS SPF SAFI . . . . . . . . . . . . . . . . 5
6.1.1. Relationship to Other BGP AFI/SAFI Tuples . . . . . . 6
6.2. Peering Models . . . . . . . . . . . . . . . . . . . . . 6
6.2.1. Sparse Peering Model . . . . . . . . . . . . . . . . 6
6.2.2. Bi-Connected Graph Heuristic . . . . . . . . . . . . 7
6.3. BGP Spine/Leaf Topology Policy . . . . . . . . . . . . . 7
6.4. BGP Peer Discovery Requirements . . . . . . . . . . . . . 8
6.5. BGP Peer Discovery . . . . . . . . . . . . . . . . . . . 9
6.5.1. BGP Peer Discovery Alternatives . . . . . . . . . . . 9
6.5.2. BGP IPv6 Simplified Peering . . . . . . . . . . . . . 9
6.5.3. BGP-LS SPF Topology Visibility for Management . . . . 10
6.5.4. Data Center Interconnect (DCI) Applicability . . . . 10
7. Non-CLOS/FAT Tree Topology Applicability . . . . . . . . . . 10
8. Non-Transit Node Capability . . . . . . . . . . . . . . . . . 10
9. BGP Policy Applicability . . . . . . . . . . . . . . . . . . 11
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
11. Security Considerations . . . . . . . . . . . . . . . . . . . 11
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
13.1. Normative References . . . . . . . . . . . . . . . . . . 11
13.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
This document complements [I-D.ietf-lsvr-bgp-spf] by discussing the
applicability of the technology in a simple and fairly common
deployment scenario, which is described in Section 4.
After describing the deployment scenario, Section 5 will describe the
reasons for BGP modifications for such deployments.
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Once the control plane routing protocol requirements are described,
Section 6 will cover the LSVR protocol enhancements to BGP to meet
these requirements and their applicability to Data Center CLOS
networks.
2. 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.
3. Recommended Reading
This document assumes knowledge of existing data center networks and
data center network topologies [CLOS]. This document also assumes
knowledge of data center routing protocols like BGP [RFC4271], BGP-
SPF [I-D.ietf-lsvr-bgp-spf], OSPF [RFC2328], as well as, data center
OAM protocols like LLDP [RFC4957] and BFD [RFC5580].
4. Common Deployment Scenario
Within a Data Center, servers are commonly interconnected the CLOS
topology [CLOS]. The CLOS topology is fully non-blocking and the
topology is realized using Equal Cost Multi-Path (ECMP). In a CLOS
topology, the minimum number of parallel paths between two servers is
determined by the width of a tier-1 stage as shown in the figure 1.
The following example illustrates multi-stage CLOS topology.
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Tier-1
+-----+
|NODE |
+->| 12 |--+
| +-----+ |
Tier-2 | | Tier-2
+-----+ | +-----+ | +-----+
+------------>|NODE |--+->|NODE |--+--|NODE |-------------+
| +-----| 9 |--+ | 10 | +--| 11 |-----+ |
| | +-----+ +-----+ +-----+ | |
| | | |
| | +-----+ +-----+ +-----+ | |
| +-----+---->|NODE |--+ |NODE | +--|NODE |-----+-----+ |
| | | +---| 6 |--+->| 7 |--+--| 8 |---+ | | |
| | | | +-----+ | +-----+ | +-----+ | | | |
| | | | | | | | | |
+-----+ +-----+ | +-----+ | +-----+ +-----+
|NODE | |NODE | Tier-3 +->|NODE |--+ Tier-3 |NODE | |NODE |
| 1 | | 2 | | 3 | | 4 | | 5 |
+-----+ +-----+ +-----+ +-----+ +-----+
| | | | | | | |
A O B O <- Servers -> Z O O O
Figure 1: Illustration of the basic CLOS
5. Justification for BGP SPF Extension
In order to simplify layer-3 routing and operations [RFC7938], many
data centers use BGP as a routing protocol to create both an underlay
and overlay network for their CLOS Topologies. However, BGP is a
path-vector routing protocol. Since it does not create a fabric
topology, it uses hop-by-hop EBGP peering to facilitate hop-by-hop
routing to create the underlay network and to resolve any overlay
next hops. The hop-by-hop BGP peering paradigm imposes several
restrictions within a CLOS. It severely prohibits a deployment of
Route Reflectors/Route Controllers as the EBGP sessions are congruent
with the data path. The BGP best-path algorithm is prefix-based and
it prevents announcements of prefixes to other BGP speakers until the
best-path decision process has been performed for the prefix at each
intermediate hop. These restrictions significantly delay the overall
convergence of the underlay network within a CLOS network.
The LSVR SPF modifications allow BGP to overcome these limitations.
Furthermore, using the BGP-LS NLRI format [RFC7752] allows the LSVR
data to be advertised for nodes, links, and prefixes in the BGP
routing domain and used for SPF computations.
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6. LSVR Applicability to CLOS Networks
With the BGP SPF extensions [I-D.ietf-lsvr-bgp-spf], the BGP best-
path computation and route computation are replaced with OSPF-like
algorithms [RFC2328] both to determine whether an BGP-LS SPF NLRI has
changed and needs to be re-advertised and to compute the BGP routes.
These modifications will significantly improve convergence of the
underlay while affording the operational benefits of a single routing
protocol [RFC7938].
Data center controllers typically require visibility to the BGP
topology to compute traffic-engineered paths. These controllers
learn the topology and other relevant information via the BGP-LS
address family [RFC7752] which is totally independent of the underlay
address families (usually IPv4/IPv6 unicast). Furthermore, in
traditional BGP underlays, all the BGP routers will need to advertise
their BGP-LS information independently. With the BGP SPF extensions,
controllers can learn the topology using the same BGP advertisements
used to compute the underlay routes. Furthermore, these data center
controllers can avail the convergence advantages of the BGP SPF
extensions. The placement of controllers can be outside of the
forwarding path or within the forwarding path.
Alternatively, as each and every router in the BGP SPF domain will
have a complete view of the topology, the operator can also choose to
configure BGP sessions in hop-by-hop peering model described in
[RFC7938] along with BFD [RFC5580]. In doing so, while the hop-by-
hop peering model lacks the inherent benefits of the controller-based
model, BGP updates need not be serialized by BGP best-path algorithm
in either of these models. This helps overall network convergence.
6.1. Usage of BGP-LS SPF SAFI
The BGP SPF extensions [I-D.ietf-lsvr-bgp-spf] define a new BGP-LS
SPF SAFI for announcement of BGP SPF link-state. The NLRI format and
its associated attributes follow the format of BGP-LS for node, link,
and prefix announcements. Whether the peering model within a CLOS
follows hop-by-hop peering described in [RFC7938] or any controller-
based or route-reflector peering, an operator can exchange BGP SPF
SAFI routes over the BGP peering by simply configuring BGP SPF SAFI
between the necessary BGP speakers.
The BGP-LS SPF SAFI can also co-exist with BGP IP Unicast SAFI which
could exchange overlapping IP routes. The routes received by these
SAFIs are evaluated, stored, and announced independently according to
the rules of [RFC4760]. The tie-breaking of route installation is a
matter of the local policies and preferences of the network operator.
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Finally, as the BGP SPF peering is done following the procedures
described in [RFC4271], all the existing transport security
mechanisms including [RFC5925] are available for the BGP-LS SPF SAFI.
6.1.1. Relationship to Other BGP AFI/SAFI Tuples
Normally, the BGP-LS AFI/SAFI is used solely to compute the underlay
and is given preference over other AFI/SAFIs. Other BGP SAFIs, e.g.,
IPv6/IPv6 Unicast VPN would use the BGP-SPF computed routes for next
hop resolution. However, if BGP-LS NLRI is also being advertised for
controller consumption, there is no need to replicate the Node, Link,
and Prefix NLRI in BGP-NLRI. Rather, additional NLRI attributes can
be advertised in the BGP-LS SPF AFI/SAFI as required (e.g., BGP-LS TE
metric extensions [RFC8571] and BGP-LS segment routing extensions
[RFC9085]).
6.2. Peering Models
As previously stated, BGP SPF can be deployed using the existing
peering model where there is a single-hop BGP session on each and
every link in the data center fabric [RFC7938]. This provides for
both the advertisement of routes and the determination of link and
neighboring switch availability. With BGP SPF, the underlay will
converge faster due to changes to the decision process that will
allow NLRI changes to be advertised faster after detecting a change.
6.2.1. Sparse Peering Model
Alternately, BFD [RFC5580] can be used to swiftly determine the
availability of links and the BGP peering model can be significantly
sparser than the data center fabric. BGP SPF sessions only need to
be established with enough peers to provide a bi-connected graph. If
IEBGP is used, then the BGP routers at tier N-1 will act as route-
reflectors for the routers at tier N.
The obvious usage of sparse peering is to avoid parallel BGP sessions
on links between the same two switches in the data center fabric.
However, this use case is not very useful since parallel layer-3
links between the same two BGP routers are rare in CLOS or Fat-Tree
topologies. Additionally, when there are multiple links, they are
often aggregated at the link layer rather than the IP layer. Two
more interesting scenarios are described below.
In current data center topologies, there is often a very dense mesh
of links between levels, e.g., leaf and spine, providing 32-way,
64-way, or more Equal-Cost Multi-Path (ECMP) paths. In these
topologies, it is desirable not to have a BGP session on every link
and techniques such as the one described in Section 6.2.2 can be used
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establish sessions on some subset of northbound links. For example,
in a Spine-Leaf topology, each leaf switch would only peer with a
subset of the spines dependent on the flooding redundancy required to
be reasonably certain that every node within the BGP-LS SPF routing
domain has the complete topology (refer to Section 6.2.1).
Alternately, controller-based data center topologies are envisioned
where BGP speakers within the data center only establish BGP sessions
with two or more controllers. In these topologies, fabric nodes
below the first tier (using [RFC7938] hierarchy) will establish BGP
multi-hop sessions with the controllers. For the multi-hop sessions,
determining the route to the controllers without depending on BGP
would need to be through some other means beyond the scope of this
document. However, the BGP discovery mechanisms described in
Section 6.5 would be one possibility.
6.2.2. Bi-Connected Graph Heuristic
With this heuristic, discovery of BGP peers is assumed, e.g., as
described in Section 6.5. Additionally, it assumed that the
direction of the peering can be ascertained. In the context of a
data center fabric, direction is either northbound (toward the
spine), southbound (toward the Top-Of-Rack (TOR) switches) or east-
west (same level in hierarchy. The determination of the direction is
beyond the scope of this document. However, it would be reasonable
to assume a technique where the TOR switches can be identified and
the number of hops to the TOR is used to determine the direction.
In this heuristic, BGP speakers allow passive session establishment
for southbound BGP sessions. For northbound sessions, BGP speakers
will attempt to maintain two northbound BGP sessions with different
switches (in data center fabrics there is normally a single layer-3
connection anyway). For east-west sessions, passive BGP session
establishment is allowed. However, BGP speaker will never actively
establish an east-west BGP session unless it cannot establish two
northbound BGP sessions.
6.3. BGP Spine/Leaf Topology Policy
One of the advantages of using BGP SPF as the underlay protocol is
that BGP policy can be applied at any level. For example, depending
upon the topology, it may be possible to aggregate prefix
advertisements using existing BGP policy. In Spine/Leaf topologies,
it is not necessary to advertise BGP-LS NLRI received by leaves
northbound to the spine nodes at the level above. If a common AS is
used for the spine nodes, this can easily be accomplished with EBGP
and a simple policy to filter advertisements from the leaves to the
spine if the first AS in the AS path is the spine AS.
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In the figure below, the leaves would not advertise any NLRI with AS
64512 as the first AS in the AS path.
+--------+ +--------+ +--------+
AS 64512 | | | | | |
for Spine | Spine 1+----+ Spine 2+- ......... -+ Spine N|
Nodes at | | | | | |
this Level +-+-+-+-++ ++-+-+-+-+ +-+-+-+-++
+------+ | | | | | | | | | | |
| +-----|-|-|------+ | | | | | | |
| | +--|-|-|--------+-|-|-----------------+ | | |
| | | | | | +---+ | | | | |
| | | | | | | +--|-|-------------------+ | |
| | | | | | | | | | +------+ +----+
| | | | | | | | | +--------------|----------+ |
| | | | | | | | +-------------+ | | |
| | | | | +----|--|----------------|--|--------+ | |
| | | | +------|--|--------------+ | | | | |
| | | +------+ | | | | | | | |
++--+--++ +-+-+--++ ++-+--+-+ ++-+--+-+
| Leaf 1|~~~~~~| Leaf 2| ........ | Leaf X| | Leaf Y|
+-------+ +-------+ +-------+ +-------+
Figure 2: Spine/Leaf Topology Policy
6.4. BGP Peer Discovery Requirements
The most basic requirement is to be able to discover the address of a
single-hop peer without pre-configuration. This is being
accomplished today with using IPv6 Router Advertisements (RA)
[RFC4861] and assuming that a BGP sessions is desired with any
discovered peer. Beyond the basic requirement, it is useful to have
to following information relating to the BGP session:
* Autonomous System (AS) and BGP Identifier of a potential peer.
The latter can be used for debugging and to decrease the
likelihood of BGP session establishment collisions.
* Security capabilities supported and for cryptographic
authentication, the security capabilities and possibly a key-chain
[RFC8177] to be used.
* Session Policy Identifier - A group number or name used to
associate common session parameters with the peer. For example,
in a data center, BGP sessions with a Top of Rack (ToR) device
could have parameters than BGP sessions between leaf and spine.
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In a data center fabric, it is often useful to know whether a peer is
southbound (towards the servers) or northbound (towards the spine or
super-spine), e.g., Section 6.2.2. A potential requirement would be
to determine this dynamically. One mechanism, without specifying all
the details, might be for the ToR switches to be identified when
installed and for the others switches in the fabric to determine
their level based on the distance from the closest ToR switch.
If there are multiple links between BGP speakers or the links between
BGP speakers are unnumbered, it is also useful to be able to
establish multi-hop sessions using the loopback addresses. This will
often require the discovery protocol to install route(s) toward the
potential peer loopback addresses prior to BGP session establishment.
Finally, a simple BGP discovery protocol could also be used to
establish a multi-hop session with one or more controllers by
advertising connectivity to one or more controllers. However, once
the multi-hop session actually traverses multiple nodes, it is
bordering a distance-vector routing protocol and possibly this is not
a good requirement for the discovery protocol.
6.5. BGP Peer Discovery
6.5.1. BGP Peer Discovery Alternatives
While BGP peer discovery is not part of [I-D.ietf-lsvr-bgp-spf],
there are, at least, three proposals for BGP peer discovery. At
least one of these mechanisms will be adopted and will be applicable
to deployments other than the data center. It is strongly
RECOMMENDED that the accepted mechanism be used in conjunction with
BGP SPF in data centers. The BGP discovery mechanism should
discovery both peer addresses and endpoints for BFD discovery.
Additionally, it would be great if there were a heuristic for
determining whether the peer is at a tier above or below the
discovering BGP speaker (refer to Section 6.2.2).
The BGP discovery mechanisms under consideration are
[I-D.acee-idr-lldp-peer-discovery],
[I-D.xu-idr-neighbor-autodiscovery], and [I-D.ietf-lsvr-l3dl].
6.5.2. BGP IPv6 Simplified Peering
In order to conserve IPv4 address space and simplify operations, BGP-
LS SPF routers in CLOS/Fat-Tree deployments can use IPv6 addresses as
peer address. For IPv4 address families, IPv6 peering as specified
in [RFC5549] can be deployed to avoid configuring IPv4 addresses on
BGP-LS SPF router interfaces. When this is done, dynamic discovery
mechanisms, as described in Section 6.5, can used to learn the global
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or link-local IPv6 peer addresses and IPv4 addresses need not be
configured on these interfaces. If IPv6 link-local peering is used,
then configuration of IPv6 global addresses is also not required and
these IPv6 link-local addresses must then be advertised in the BGP-LS
Link Descriptor IPv6 Address TLV (262) [RFC7752].
6.5.3. BGP-LS SPF Topology Visibility for Management
Irrespective of whether or not BGP-LS SPF is used for route
calculation, the BGP-LS SPF route advertisements can be used to
periodically construct the CLOS/FAT Tree topology. This is
especially useful in deployments where an IGP is not used and the
base BGP-LS routes [RFC7752] are not available. The resultant
topology visibility can then be used for troubleshooting and
consistency checking. This would normally be done on a central
controller or other management tool which could also be used for
fabric data path verification. The precise algorithms and
heuristics, as well as, the complete set of management applications
is beyond the scope of this document.
6.5.4. Data Center Interconnect (DCI) Applicability
Since BGP SPF is to be used for the routing underlay and DCI gateway
boxes typically have direct or very simple connectivity, BGP external
sessions would typically not include the BGP SPF SAFI.
7. Non-CLOS/FAT Tree Topology Applicability
The BGP SPF extensions [I-D.ietf-lsvr-bgp-spf] can be used in other
topologies and avail the inherent convergence improvements.
Additionally, sparse peering techniques may be utilized Section 6.2.
However, determining whether or to establish a BGP session is more
complex and the heuristic described in Section 6.2.2 cannot be used.
In such topologies, other techniques such as those described in
[I-D.ietf-lsr-dynamic-flooding] may be employed. One potential
deployment would be the underlay for a Service Provider (SP) backbone
where usage of a single protocol, i.e., BGP, is desired.
8. Non-Transit Node Capability
In certain scenarios, a BGP node wishes to participate in the BGP SPF
topology but never be used for transit traffic. These in include
situations where a server wants to make application services
available to clients homed at subnets throughout the BGP SPF domain
but does not ever want to be used as a router (i.e., carry transit
traffic). Another specific instance is where a controller is
resident on a server and direct connectivity to the controller is
required throughout the entire domain. This can readily be
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accomplished using the BGP-LS Node NLRI Attribute SPF Status TLV as
described in [I-D.ietf-lsvr-bgp-spf].
9. BGP Policy Applicability
Existing BGP policy including aggregation and prefix filtering may be
used in conjunction with the BGP-LS SPF SAFI. When aggregation
policy is used, BGP-LS SPF prefix NLRI will be originated for the
aggregate prefix and BGP-LS SPF prefix NLRI for components will be
filtered. Additionally, link and node NLRI may be filtered and the
abstracted by the prefix NLRI.
When BGP policy is used with the BGP-LS SPF SAFI, BGP speakers in the
BGP-LS SPF routing domain will not all have the same set of NLRI and
will compute a different BGP local routing table. Consequently, care
must be taken to assure routing is consistent and blackholes or
routing loops do not ensue. However, this is no different than if
tradition BGP routing using the IPv4 and IPv6 address families were
used.
10. IANA Considerations
No IANA updates are requested by this document.
11. Security Considerations
This document introduces no new security considerations above and
beyond those already specified in the [RFC4271] and
[I-D.ietf-lsvr-bgp-spf].
12. Acknowledgements
The authors would like to thank Alvaro Retana, Yan Filyurin, and
Boris Hassanov for their review and comments.
13. References
13.1. Normative References
[I-D.ietf-lsvr-bgp-spf]
Patel, K., Lindem, A., Zandi, S., and W. Henderickx, "BGP
Link-State Shortest Path First (SPF) Routing", Work in
Progress, Internet-Draft, draft-ietf-lsvr-bgp-spf-29, 25
November 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-lsvr-bgp-spf-29>.
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[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>.
[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>.
13.2. Informative References
[CLOS] "A Study of Non-Blocking Switching Networks", The Bell
System Technical Journal, Vol. 32(2), DOI
10.1002/j.1538-7305.1953.tb01433.x, March 1953.
[I-D.acee-idr-lldp-peer-discovery]
Lindem, A., Patel, K., Zandi, S., Haas, J., and X. Xu,
"BGP Logical Link Discovery Protocol (LLDP) Peer
Discovery", Work in Progress, Internet-Draft, draft-acee-
idr-lldp-peer-discovery-17, 4 January 2024,
<https://datatracker.ietf.org/doc/html/draft-acee-idr-
lldp-peer-discovery-17>.
[I-D.ietf-lsr-dynamic-flooding]
Li, T., Psenak, P., Chen, H., Jalil, L., and S. Dontula,
"Dynamic Flooding on Dense Graphs", Work in Progress,
Internet-Draft, draft-ietf-lsr-dynamic-flooding-15, 6
February 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-lsr-dynamic-flooding-15>.
[I-D.ietf-lsvr-l3dl]
Bush, R., Austein, R., Housley, R., and K. Patel, "Layer-3
Discovery and Liveness", Work in Progress, Internet-Draft,
draft-ietf-lsvr-l3dl-12, 11 February 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-lsvr-
l3dl-12>.
[I-D.xu-idr-neighbor-autodiscovery]
Xu, X., Talaulikar, K., Bi, K., Tantsura, J., and N.
Triantafillis, "BGP Neighbor Discovery", Work in Progress,
Internet-Draft, draft-xu-idr-neighbor-autodiscovery-12, 26
November 2019, <https://datatracker.ietf.org/doc/html/
draft-xu-idr-neighbor-autodiscovery-12>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>.
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[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>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>.
[RFC4957] Krishnan, S., Ed., Montavont, N., Njedjou, E., Veerepalli,
S., and A. Yegin, Ed., "Link-Layer Event Notifications for
Detecting Network Attachments", RFC 4957,
DOI 10.17487/RFC4957, August 2007,
<https://www.rfc-editor.org/info/rfc4957>.
[RFC5549] Le Faucheur, F. and E. Rosen, "Advertising IPv4 Network
Layer Reachability Information with an IPv6 Next Hop",
RFC 5549, DOI 10.17487/RFC5549, May 2009,
<https://www.rfc-editor.org/info/rfc5549>.
[RFC5580] Tschofenig, H., Ed., Adrangi, F., Jones, M., Lior, A., and
B. Aboba, "Carrying Location Objects in RADIUS and
Diameter", RFC 5580, DOI 10.17487/RFC5580, August 2009,
<https://www.rfc-editor.org/info/rfc5580>.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010, <https://www.rfc-editor.org/info/rfc5925>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[RFC7938] Lapukhov, P., Premji, A., and J. Mitchell, Ed., "Use of
BGP for Routing in Large-Scale Data Centers", RFC 7938,
DOI 10.17487/RFC7938, August 2016,
<https://www.rfc-editor.org/info/rfc7938>.
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[RFC8177] Lindem, A., Ed., Qu, Y., Yeung, D., Chen, I., and J.
Zhang, "YANG Data Model for Key Chains", RFC 8177,
DOI 10.17487/RFC8177, June 2017,
<https://www.rfc-editor.org/info/rfc8177>.
[RFC8571] Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and
C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of
IGP Traffic Engineering Performance Metric Extensions",
RFC 8571, DOI 10.17487/RFC8571, March 2019,
<https://www.rfc-editor.org/info/rfc8571>.
[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>.
Authors' Addresses
Keyur Patel
Arrcus, Inc.
2077 Gateway Pl
San Jose, CA, 95110
United States of America
Email: keyur@arrcus.com
Acee Lindem
LabN Consulting, L.L.C.
301 Midenhall Way
Cary, NC, 95110
United States of America
Email: acee.ietf@gmail.com
Shawn Zandi
Linkedin
222 2nd Street
San Francisco, CA 94105
United States of America
Email: szandi@linkedin.com
Gaurav Dawra
Linkedin
222 2nd Street
San Francisco, CA 94105
United States of America
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Email: gdawra@linkedin.com
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