Internet DRAFT - draft-ietf-bfd-seamless-use-case
draft-ietf-bfd-seamless-use-case
Network Working Group S. Aldrin
Internet-Draft Google, Inc
Intended status: Informational C. Pignataro
Expires: November 7, 2016 Cisco
G. Mirsky
Ericsson
N. Kumar
Cisco
May 6, 2016
Seamless Bidirectional Forwarding Detection (S-BFD) Use Cases
draft-ietf-bfd-seamless-use-case-08
Abstract
This document describes various use cases for a Seamless
Bidirectional Forwarding Detection (S-BFD), and provides requirements
such that protocol mechanisms allow for a simplified detection of
forwarding failures.
These use cases support S-BFD, as a simplified mechanism to use
Bidirectional Forwarding Detection (BFD) with large portions of
negotiation aspects eliminated, accelerating the establishment of a
BFD session. S-BFD benefits include quick provisioning as well as
improved control and flexibility to network nodes initiating the path
monitoring.
Status of This Memo
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This Internet-Draft will expire on November 7, 2016.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Introduction to Seamless BFD . . . . . . . . . . . . . . . . 4
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Unidirectional Forwarding Path Validation . . . . . . . . 5
3.2. Validation of the Forwarding Path Prior to Switching
Traffic . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Centralized Traffic Engineering . . . . . . . . . . . . . 7
3.4. BFD in Centralized Segment Routing . . . . . . . . . . . 8
3.5. Efficient BFD Operation under Resource Constraints . . . 8
3.6. BFD for Anycast Addresses . . . . . . . . . . . . . . . . 8
3.7. BFD Fault Isolation . . . . . . . . . . . . . . . . . . . 9
3.8. Multiple BFD Sessions to the Same Target Node . . . . . . 9
3.9. An MPLS BFD Session Per ECMP Path . . . . . . . . . . . . 10
4. Detailed Requirements for a Seamless BFD . . . . . . . . . . 10
5. Security Considerations . . . . . . . . . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
Bidirectional Forwarding Detection (BFD) is a lightweight protocol,
as defined in [RFC5880], used to detect forwarding failures. Various
protocols and applications rely on BFD as its clients for failure
detection. Even though the protocol is lightweight and simple, there
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are certain use cases where faster setting up of sessions and faster
continuity check of the data forwarding paths is necessary. This
document identifies these use cases and consequent requirements, such
that enhancements and extensions result in a Seamless BFD (S-BFD)
protocol.
BFD is a simple lightweight "Hello" protocol to detect data plane
failures. With dynamic provisioning of forwarding paths on a large
scale, establishing BFD sessions for each of those paths not only
creates operational complexity, but also causes undesirable delay in
establishing or deleting sessions. The existing session
establishment mechanism of the BFD protocol has to be enhanced in
order to minimize the time for the session to come up to validate the
forwarding path.
This document specifically identifies various use cases and
corresponding requirements in order to enhance BFD and other
supporting protocols. Specifically, one key goal is removing the
time delay (i.e., the "seam") between a network node wants to perform
a continuity test and the node completes that continuity test.
Consequently, "Seamless BFD" (S-BFD) has been chosen as the name for
this mechanism.
While the identified requirements could meet various use cases, it is
outside the scope of this document to identify all of the possible
and necessary requirements. Solutions to the identified uses cases
and protocol specific enhancements or proposals are outside the scope
of this document as well. Protocol definitions to support these use
cases can be found at [I-D.ietf-bfd-seamless-base] and
[I-D.ietf-bfd-seamless-ip].
1.1. Terminology
The reader is expected to be familiar with the BFD [RFC5880], IP
[RFC0791] [RFC2460], MPLS [RFC3031], and Segment Routing (SR)
[I-D.ietf-spring-segment-routing] terminologies and protocol
constructs.
1.2. 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
[RFC2119].
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2. Introduction to Seamless BFD
BFD, as defined in [RFC5880], requires two network nodes to exchange
locally allocated discriminators. These discriminators enable the
identification of the sender and the receiver of BFD packets over the
particular session. Subsequently, BFD performs proactive continuity
monitoring of the forwarding path between the two. Several
specifications describe BFD's multiple deployment uses:
[RFC5881] defines BFD over IPv4 and IPv6 for single IP hops
[RFC5883] defines BFD over multihop paths
[RFC5884] defines BFD for MPLS Label Switched Paths (LSPs)
[RFC5885] defines BFD for MPLS Pseudowires (PWs)
Currently, BFD is best suited to verify that two endpoints are
mutually reachable or that an existing connection continues to be up
and alive. In order for BFD to be able to initially verify that a
connection is valid and that it connects the expected set of
endpoints, it is necessary to provide each endpoint with the
discriminators associated with the connection at each endpoint prior
to initiating BFD sessions. The discriminators are used to verify
that the connection is up and verifiable. Currently, the exchange of
discriminators and the demultiplexing of the initial BFD packets is
application dependent.
If this information is already known to the end-points of a potential
BFD session, the initial handshake including an exchange of
discriminators is unnecessary and it is possible for the endpoints to
begin BFD messaging seamlessly. A key objective of the S-BFD use
cases described in this document is to avoid needing to exchange the
initial packets before the BFD session can be established, with the
goal of getting to the established state more quickly; in other
words, the initial exchange of discriminator information is an
unnecessary extra step that may be avoided for these cases.
In a given scenario, an entity (such as an operator, or a centralized
controller) determines a set of network entities to which BFD
sessions might need to be established. In traditional BFD, each of
those network entities chooses a BFD discriminator for each BFD
session that the entity will participate in (see Section 6.3 of
[RFC5880]). However, a key goal of a Seamless BFD is to provide
operational simplification. In this context, for S-BFD, each of
those network entities is assigned one or more BFD discriminators,
and allowing those network entities to use one discriminator value
for multiple sessions. Therefore, there may be only one or a few
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discriminators assigned to a node. These network entities will
create an S-BFD listener session instance that listens for incoming
BFD control packets. When the mappings between specific network
entities and their corresponding BFD discriminators are known to
other network nodes belonging to the same administrative domain,
then, without having received any BFD packet from a particular
target, a network entity in this network is able to send a BFD
control packet to the target's assigned discriminator in the Your
Discriminator field. The target network node, upon reception of such
BFD control packet, will transmit a response BFD control packet back
to the sender.
3. Use Cases
As per the BFD protocol [RFC5880], BFD sessions are established using
handshake mechanism prior to validating the forwarding path. This
section outlines some use cases where the existing mechanism may not
be able to satisfy the requirements identified. In addition, some of
the use cases also stress the need for expedited BFD session
establishment while preserving benefits of forwarding failure
detection using existing BFD mechanics. Both these high-level goals
result in the S-BFD use cases.
3.1. Unidirectional Forwarding Path Validation
Even though bidirectional verification of forwarding path is useful,
there are scenarios where verification is only required in one
direction between a pair of nodes. One such case is, when a static
route uses BFD to validate reachability to the next-hop IP router.
In this case, the static route is established from one network entity
to another. The requirement in this case is only to validate the
forwarding path for that statically established unidirectional path.
Validation of the forwarding path in the direction of the target
entity to the originating entity is not required, in this scenario.
Many LSPs have the same unidirectional characteristics and
unidirectional validation requirements. Such LSPs are common in
Segment Routing and LDP based MPLS networks. A final example is when
a unidirectional tunnel uses BFD to validate reachability of an
egress node.
Additionally, there are operational implications to the
unidirectional path validation. If the traditional BFD is to be
used, the target network entity has to be provisioned as well as an
initiator, even though the reverse path validation with the BFD
session is not required. However, in the case of unidirectional BFD,
there is no need for provisioning on the target network entity, only
the source one.
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In this use case, a BFD session could be established in a single
direction. When the targeted network entity receives the packet, it
identities the packet as BFD in an application-specific manner (for
example, a destination UDP port number). Subsequently, the BFD
module processes the packet, using the Your Discriminator value as
context. Then, the network entity sends a response to the
originator. This does not necessitate the requirement for
establishment of a bi-directional session, hence the two way
handshake to exchange discriminators is not needed. The target node
does not need to know the My Discriminator of the source node.
Thus, a requirement for BFD for this use case is to enable session
establishment from source network entity to target network entity
without the need to have a session (and state) for the reverse
direction. Further, another requirement is that the BFD response
from target back to sender can take any (in-band or out-of-band)
path. The BFD module in the target network entity (for the BFD
session), upon receipt of BFD packet, starts processing the BFD
packet based on the discriminator received. The source network
entity can therefore establish a unidirectional BFD session without
the bidirectional handshake and exchange of discriminators for
session establishment.
3.2. Validation of the Forwarding Path Prior to Switching Traffic
This use case is when BFD is used to verify reachability before
sending traffic via a path/LSP. This comes with a cost, which is
that traffic is prevented to use the path/LSP until BFD is able to
validate the reachability, which could take seconds due to BFD
session bring-up sequences [RFC5880], LSP ping bootstrapping
[RFC5884], etc. This use case would be better supported by
eliminating the need for the initial BFD session negotiation.
All it takes to be able to send BFD packets to a target, and the
target properly demultiplexing these, is for the source network
entities to know what the discriminator values to be used for the
session. The same is the case for S-BFD: the three-way handshake
mechanism is eliminated during the bootstrap of BFD sessions.
However, this information is required at each entity to verify that
BFD messages are being received from the expected end-points, hence
the handshake mechanism serves no purpose. Elimination of the
unnecessary handshake mechanism allows for faster reachability
validation of BFD provisioned paths/LSPs.
In addition, it is expected that some MPLS technologies will require
traffic engineered LSPs to be created dynamically, perhaps driven by
external applications, as e.g. in Software Defined Networks (SDN).
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It will be desirable to perform BFD validation as soon as the LSPs
are created, so as to use them.
In order to support this use case, an S-BFD session is established
without the need for session negotiation and exchange of
discriminators.
3.3. Centralized Traffic Engineering
Various technologies in the SDN domain that involve controller-based
networks have evolved such that the intelligence, traditionally
placed in a distributed and dynamic control plane, is separated from
the networking entities themselves; instead, it resides in a
(logically) centralized place. There are various controllers that
perform the function in establishment of forwarding paths for the
data flow. Traffic engineering (TE) is one important function, where
the path of the traffic flow is engineered, depending upon various
attributes and constraints of the traffic paths as well as the
network state.
When the intelligence of the network resides in a centralized entity,
the ability to manage and maintain the dynamic network and its
multiple data paths and node reachability becomes a challenge. One
way to ensure the forwarding paths are valid and working is done by
validation using BFD. When traffic engineered tunnels are created,
it is operationally critical to ensure that the forwarding paths are
working, prior to switching the traffic onto the engineered tunnels.
In the absence of distributed control plane protocols, it may be
desirable to verify any arbitrary forwarding path in the network.
With tunnels being engineered by a centralized entity, when the
network state changes, traffic has to be switched with minimum
latency and without black-holing of the data.
It is highly desirable in this centralized traffic engineering use
case that the traditional BFD session establishment and validation of
the forwarding path does not become a bottleneck. If the controller
or other centralized entity is able to very rapidly verify the
forwarding path of a traffic engineered tunnel, it could steer the
traffic onto the traffic engineered tunnel very quickly thus
minimizing adverse effect on a service. This is even more useful and
necessary when the scale of the network and number of traffic
engineered tunnels grows.
The cost associated with the time required for BFD session
negotiation and establishment of BFD sessions to identify valid paths
is very high when providing network redundancy is a critical issue.
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3.4. BFD in Centralized Segment Routing
A monitoring technique of a Segment Routing network based on a
centralized controller is described in [I-D.ietf-spring-oam-usecase].
Specific OAM requirements for Segment Routing are captured in
[I-D.ietf-spring-sr-oam-requirement]. In validating this use case,
one of the requirements is to ensure that the BFD packet's behavior
is according to the monitoring specified for the segment, and that
the packet is U-turned at the expected node. This criteria ensures
the continuity check to the adjacent segment-id.
To support this use case, the operational requirement is for BFD,
initiated from a centralized controller, to perform liveness
detection for any given segment under its domain.
3.5. Efficient BFD Operation under Resource Constraints
When BFD sessions are being setup, torn down or modified (i.e., when
parameters such as interval and multiplier are being modified), BFD
requires additional packets other than scheduled packet transmissions
to complete the negotiation procedures (i.e., P/F bits). There are
scenarios where network resources are constrained: a node may require
BFD to monitor very large number of paths, or BFD may need to operate
in low powered and traffic sensitive networks; these include
microwave, low powered nano-cells, and others. In these scenarios,
it is desirable for BFD to slow down, speed up, stop, or resume at-
will and with minimal number of additional BFD packets exchanged to
modify the session or establish a new one.
The established BFD session parameters and attributes like
transmission interval, receiver interval, etc., need to be modifiable
without changing the state of the session.
3.6. BFD for Anycast Addresses
The BFD protocol requires two endpoints to host BFD sessions, both
sending packets to each other. This BFD model does not fit well with
anycast address monitoring, as BFD packets transmitted from a network
node to an anycast address will reach only one of potentially many
network nodes hosting the anycast address.
This use case verifies that a source node can send a packet to an
anycast address, and that the target node to which the packet is
delivered can send a response packet to the source node. Traditional
BFD cannot fulfill this requirement, since it does not provide for a
set of BFD agents to collectively form one endpoint of a BFD session.
The concept of a Target Listener in S-BFD solves this requirement.
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To support this use case, the BFD sender transmits BFD packets, which
are received by any of the nodes hosting the anycast address to which
the BFD packets being sent. The anycast target that receives the BFD
packet, responds. This use case does not imply the BFD session
establishment with every node hosting the anycast address.
Consequently, in this any cast use case, target nodes that do not
happen to receive any of the BFD packets do not need to maintain any
state, and the source node does not need to maintain separate state
for each target node.
3.7. BFD Fault Isolation
BFD for multihop paths [RFC5883] and BFD for MPLS LSPs [RFC5884]
perform end-to-end validation, traversing multiple network nodes.
BFD has been designed to declare failure upon lack of consecutive
packet reception, which can be caused by a fault anywhere along these
path. Fast failure detection allows for rapid fault detection and
consequent rapid path recovery procedures. However, operators often
have to follow up, manually or automatically, to attempt to identify
and localize the fault that caused BFD sessions to fail (i.e., fault
isolation). The usage of other tools to isolate the fault (e.g.,
traceroute) may cause the packets to traverse a different path
through the network, if Equal-Cost Multipath (ECMP) is used. In
addition, the longer it takes from BFD session failure to starting
fault isolation, the more likely that the fault will not be able to
be isolated (e.g., a fault can get corrected or routed around). If
BFD had built-in fault isolation capability, fault isolation can get
triggered at the earliest sign of fault detection. This embedded
fault isolation will be more effective when those BFD fault isolation
packets are load balanced in the same way as the BFD packets that
were dropped, detecting the fault.
This use case describes S-BFD fault isolation capabilities, utilizing
a TTL field (e.g., as in Section 5.1.1 of [I-D.ietf-bfd-seamless-ip])
or using status indicating fields.
3.8. Multiple BFD Sessions to the Same Target Node
BFD is capable of providing very fast failure detection, as relevant
network nodes continuously transmit BFD packets at the negotiated
rate. If BFD packet transmission is interrupted, even for a very
short period of time, BFD can declare a failure irrespective of path
liveliness. It is possible, on a system where BFD is running, for
certain events (intentionally or unintentionally) to cause a short
interruption of BFD packet transmissions. With distributed
architectures of BFD implementations, this case can be protected. In
this case, the use case of an S-BFD node running multiple BFD
sessions to a targets, with those sessions hosted on different system
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modules (e.g., in different CPU instances). This can reduce BFD
false failures, resulting in more stable network.
To support this use case, a mapping between the multiple
discriminators on a single system, and the specific entity within the
system is required.
3.9. An MPLS BFD Session Per ECMP Path
BFD for MPLS LSPs, defined in [RFC5884], describes procedures to run
BFD as LSP in-band continuity check mechanism, through usage of MPLS
echo request [RFC4379] to bootstrap the BFD session on the target
(i.e., egress) node. Section 4 of [RFC5884] also describes a
possibility of running multiple BFD sessions per alternative paths of
LSP. [RFC7726] further clarified the procedures, both for ingress
and egress nodes, of how to bootstrap, maintain, and remove multiple
BFD sessions for the same <MPLS LSP, FEC> tuple. However, this
mechanism still requires the use of MPLS LSP Ping for bootstrapping,
round-trips for initialization, and keeping state at the receiver.
In the presence of ECMP within an MPLS LSP, it may be desirable to
run in-band monitoring that exercises every path of this ECMP.
Otherwise there will be scenarios where in-band BFD session remains
up through one path but traffic is black-holing over another path. A
BFD session per ECMP path of an LSP requires the definition of
procedures that update [RFC5884] in terms of how to bootstrap and
maintain the correct set of BFD sessions on the egress node.
However, for traditional BFD, that requires the constant use of MPLS
Echo Request messages to create and delete BFD sessions on the egress
node, when ECMP paths and/or corresponding load balance hash keys
change. If a BFD session over any paths of the LSP can be
instantiated, stopped and resumed without requiring additional
procedures of bootstrapping via an MPLS echo request message, it
would greatly simplify both implementations and operations, and
benefits network devices as less processing are required by them.
To support this requirement, multiple S-BFD sessions need to be
established over different ECMP paths from the same source to target
node.
4. Detailed Requirements for a Seamless BFD
REQ#1: A target network entity (for the S-BFD session), upon
receipt of the S-BFD packet, MUST process the packet based
on the discriminator received in the BFD packet. If the
S-BFD context is found, the target network entity MUST be
able to send a response.
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REQ#2: The source network entity MUST be able to establish a
unidirectional S-BFD session without the bidirectional
handshake of discriminators for session establishment.
REQ#3: The S-BFD session MUST be able to be established without the
need for exchange of discriminators in session negotiation.
REQ#4: In a Segment Routed network, S-BFD MUST be able to perform
liveness detection initiated from a centralized controller
for any given segment under its domain.
REQ#5: The established S-BFD session parameters and attributes,
such as transmission interval, reception interval, etc.,
MUST be modifiable without changing the state of the
session.
REQ#6: An S-BFD source network entity MUST be able to send S-BFD
control packets to an anycast address which are received by
any node hosting that address, and must be able to receive
responses from any of these anycast nodes, without
establishing a separate BFD session with every node hosing
the anycast address.
REQ#7: S-BFD SHOULD support fault isolation capability, which MAY
be triggered when a fault is encountered.
REQ#8: S-BFD SHOULD be able to establish multiple sessions between
the same pair of source and target nodes. This requirement
enables but does not guarantee the ability to monitor
diverge paths in ECMP environments. It also provides
resiliency in distributed router architectures. The mapping
between BFD discriminators and particular entities (e.g.,
ECMP paths, or Line Cards) is out the scope of the S-BFD
specification.
REQ#9: The S-BFD protocol MUST provide mechanisms for loop
detection and prevention, protecting against malicious
attacks attempting to create packet loops.
REQ#10: S-BFD MUST incorporate robust security protections against
impersonators, malicions actors, and various active and
passive attacks. The simple and accelerated establishment
of an S-BFD session should not negatively affect security.
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5. Security Considerations
This document details the use cases and identifies various associated
requirements. Some of these requirements are security related. The
use cases herein described do not expose a system to abuse or to
additional security risks. Since some negotiation aspects are
eliminated, a misconfiguration can result in S-BFD packets being sent
to an incorrect node. If this receiving node runs S-BFD, the packet
will be discarted because of the discriminator mismatch. If the node
does not run S-BFD, the packet will be naturally discarded.
The proposed new protocols, extensions, and enhancements for a
Seamless BFD supporting these use cases and realizing these
requirements will address the associated security considerations. A
Seamless BFD should not have reduced security capabilities as
compared to traditional BFD.
6. IANA Considerations
There are no IANA considerations introduced by this document.
7. Acknowledgements
The authors would like to thank Tobias Gondrom and Eric Gray, for
their insightful and useful comments. The authors appreciate the
thorough review and comments provided by Dale R. Worley.
8. Contributors
The following are key contributors to this document:
Manav Bhatia, Ionos Networks
Satoru Matsushima, Softbank
Glenn Hayden, ATT
Santosh P K
Mach Chen, Huawei
Nobo Akiya, Big Switch Networks
9. References
9.1. 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>.
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[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<http://www.rfc-editor.org/info/rfc5880>.
[RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,
DOI 10.17487/RFC5881, June 2010,
<http://www.rfc-editor.org/info/rfc5881>.
[RFC5883] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD) for Multihop Paths", RFC 5883, DOI 10.17487/RFC5883,
June 2010, <http://www.rfc-editor.org/info/rfc5883>.
[RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
"Bidirectional Forwarding Detection (BFD) for MPLS Label
Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884,
June 2010, <http://www.rfc-editor.org/info/rfc5884>.
[RFC5885] Nadeau, T., Ed. and C. Pignataro, Ed., "Bidirectional
Forwarding Detection (BFD) for the Pseudowire Virtual
Circuit Connectivity Verification (VCCV)", RFC 5885,
DOI 10.17487/RFC5885, June 2010,
<http://www.rfc-editor.org/info/rfc5885>.
9.2. Informative References
[I-D.ietf-bfd-seamless-base]
Akiya, N., Pignataro, C., Ward, D., Bhatia, M., and J.
Networks, "Seamless Bidirectional Forwarding Detection
(S-BFD)", draft-ietf-bfd-seamless-base-09 (work in
progress), April 2016.
[I-D.ietf-bfd-seamless-ip]
Akiya, N., Pignataro, C., and D. Ward, "Seamless
Bidirectional Forwarding Detection (S-BFD) for IPv4, IPv6
and MPLS", draft-ietf-bfd-seamless-ip-04 (work in
progress), April 2016.
[I-D.ietf-spring-oam-usecase]
Geib, R., Filsfils, C., Pignataro, C., and N. Kumar, "A
Scalable and Topology-Aware MPLS Dataplane Monitoring
System", draft-ietf-spring-oam-usecase-03 (work in
progress), April 2016.
Aldrin, et al. Expires November 7, 2016 [Page 13]
Internet-Draft S-BFD Use Cases May 2016
[I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Decraene, B., Litkowski, S.,
and R. Shakir, "Segment Routing Architecture", draft-ietf-
spring-segment-routing-07 (work in progress), December
2015.
[I-D.ietf-spring-sr-oam-requirement]
Kumar, N., Pignataro, C., Akiya, N., Geib, R., Mirsky, G.,
and S. Litkowski, "OAM Requirements for Segment Routing
Network", draft-ietf-spring-sr-oam-requirement-01 (work in
progress), December 2015.
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981,
<http://www.rfc-editor.org/info/rfc791>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001,
<http://www.rfc-editor.org/info/rfc3031>.
[RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol
Label Switched (MPLS) Data Plane Failures", RFC 4379,
DOI 10.17487/RFC4379, February 2006,
<http://www.rfc-editor.org/info/rfc4379>.
[RFC7726] Govindan, V., Rajaraman, K., Mirsky, G., Akiya, N., and S.
Aldrin, "Clarifying Procedures for Establishing BFD
Sessions for MPLS Label Switched Paths (LSPs)", RFC 7726,
DOI 10.17487/RFC7726, January 2016,
<http://www.rfc-editor.org/info/rfc7726>.
Authors' Addresses
Sam Aldrin
Google, Inc
Email: aldrin.ietf@gmail.com
Carlos Pignataro
Cisco Systems, Inc.
Email: cpignata@cisco.com
Aldrin, et al. Expires November 7, 2016 [Page 14]
Internet-Draft S-BFD Use Cases May 2016
Greg Mirsky
Ericsson
Email: gregory.mirsky@ericsson.com
Nagendra Kumar
Cisco Systems, Inc.
Email: naikumar@cisco.com
Aldrin, et al. Expires November 7, 2016 [Page 15]
