Internet DRAFT - draft-xu-mpls-sr-over-ip
draft-xu-mpls-sr-over-ip
Network Working Group X. Xu
Internet-Draft Alibaba
Intended status: Standards Track S. Bryant
Expires: December 3, 2018 Huawei
A. Farrel
Juniper
S. Hassan
Cisco
W. Henderickx
Nokia
Z. Li
Huawei
June 1, 2018
SR-MPLS over IP
draft-xu-mpls-sr-over-ip-01
Abstract
MPLS Segment Routing (SR-MPLS in short) is an MPLS data plane-based
source routing paradigm in which the sender of a packet is allowed to
partially or completely specify the route the packet takes through
the network by imposing stacked MPLS labels on the packet. SR-MPLS
could be leveraged to realize a source routing mechanism across MPLS,
IPv4, and IPv6 data planes by using an MPLS label stack as a source
routing instruction set while preserving backward compatibility with
SR-MPLS.
This document describes how SR-MPLS capable routers and IP-only
routers can seamlessly co-exist and interoperate through the use of
SR-MPLS label stacks and IP encapsulation/tunneling such as MPLS-in-
UDP as defined in RFC 7510.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 3, 2018.
Copyright Notice
Copyright (c) 2018 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Procedures of SR-MPLS over IP . . . . . . . . . . . . . . . . 5
4.1. Forwarding Entry Construction . . . . . . . . . . . . . . 5
4.2. Packet Forwarding Procedures . . . . . . . . . . . . . . 7
4.2.1. Packet Forwarding with Penultimate Hop Popping . . . 8
4.2.2. Packet Forwarding without Penultimate Hop Popping . . 9
4.2.3. Additional Forwarding Procedures . . . . . . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
MPLS Segment Routing (SR-MPLS in short)
[I-D.ietf-spring-segment-routing-mpls] is an MPLS data plane-based
source routing paradigm in which the sender of a packet is allowed to
partially or completely specify the route the packet takes through
the network by imposing stacked MPLS labels on the packet. SR-MPLS
could be leveraged to realize a source routing mechanism across MPLS,
IPv4, and IPv6 data planes by using an MPLS label stack as a source
routing instruction set while preserving backward compatibility with
SR-MPLS. More specifically, the source routing instruction set
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information contained in a source routed packet could be uniformly
encoded as an MPLS label stack no matter whether the underlay is
IPv4, IPv6, or MPLS.
This document describes how SR-MPLS capable routers and IP-only
routers can seamlessly co-exist and interoperate through the use of
SR-MPLS label stacks and IP encapsulation/tunneling such as MPLS-in-
UDP [RFC7510].
Although the source routing instructions are encoded as MPLS labels,
this is a hardware convenience rather than an indication that the
whole MPLS protocol stack needs to be deployed. In particular, the
MPLS control protocols are not used in this or any other form of SR-
MPLS.
Section 3 describes various use cases for the tunneling SR-MPLS over
IP. Section 4 describes a typical application scenario and how the
packet forwarding happens.
2. Terminology
This memo makes use of the terms defined in [RFC3031] and
[I-D.ietf-spring-segment-routing-mpls].
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. Use Cases
Tunneling SR-MPLS using IPv4 and/or IPv6 tunnels is useful at least
in the following use cases:
o Incremental deployment of the SR-MPLS technology may be
facilitated by tunneling SR-MPLS packets across parts of a network
that are not SR-MPLS enabled using an IP tunneling mechanism such
as MPLS-in-UDP [RFC7510]. The tunnel destination address is the
address of the next SR-MPLS-capable node along the path (i.e., the
egress of the active node segment). This is shown in Figure 1.
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________________________
_______ ( ) _______
( ) ( IP Network ) ( )
( SR-MPLS ) ( ) ( SR-MPLS )
( Network ) ( ) ( Network )
( -------- -------- )
( | Border | SR-in-UDP Tunnel | Border | )
( | Router |========================| Router | )
( | R1 | | R2 | )
( -------- -------- )
( ) ( ) ( )
( ) ( ) ( )
(_______) ( ) (_______)
(________________________)
Figure 1: SR-MPLS in UDP to Tunnel Between SR-MPLS Sites
o If encoding of entropy is desired, IP tunneling mechanisms that
allow encoding of entropy, such as MPLS-in-UDP encapsulation
[RFC7510] where the source port of the UDP header is used as an
entropy field, may be used to maximize the utilization of ECMP
and/or UCMP, specially when it is difficult to make use of entropy
label mechanism. Refer to [I-D.ietf-mpls-spring-entropy-label])
for more discussion about using entropy label in SR-MPLS.
o Tunneling MPLS into IP provides a technology that enables SR in an
IPv4 and/or IPv6 network where the routers do not support SRv6
capabilities [I-D.ietf-6man-segment-routing-header] and where MPLS
forwarding is not an option. This is shown in Figure Figure 2.
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__________________________________
__( IP Network )__
__( )__
( -- -- -- )
-------- -- -- |SR| -- |SR| -- |SR| -- --------
| Ingress| |IR| |IR| | | |IR| | | |IR| | | |IR| | Egress |
--->| Router |===========| |======| |======| |======| Router |--->
| SR | | | | | | | | | | | | | | | | | | SR |
-------- -- -- | | -- | | -- | | -- --------
(__ -- -- -- __)
(__ __)
(__________________________________)
Key:
IR : IP-only Router
SR : SR-MPLS-capable Router
== : SR-MPLS in UDP Tunnel
Figure 2: SR-MPLS Enabled Within an IP Network
4. Procedures of SR-MPLS over IP
This section describes the construction of forwarding information
base (FIB) entries and the forwarding behavior that allow the
deployment of SR-MPLS when some routers in the network are IP only
(i.e., do not support SR-MPLS). Note that the examples described in
Section 4.1 and Section 4.2 assume that OSPF or ISIS is enabled: in
fact, other mechanisms of discovery and advertisement could be used
including other routing protocols (such as BGP) or a central
controller.
4.1. Forwarding Entry Construction
This sub-section describes the how to construct the forwarding
information base (FIB) entry on an SR-MPLS-capable router when some
or all of the next-hops along the shortest path towards a prefix-SID
are IP-only routers.
Consider router A that receives a labeled packet with top label L(E)
that corresponds to the prefix-SID SID(E) of prefix P(E) advertised
by router E. Suppose the ith next-hop router (termed NHi) along the
shortest path from router A toward SID(E) is not SR-MPLS capable
while both routers A and E are SR-MPLS capable. The following
processing steps apply:
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o Router E is SR-MPLS capable so it advertises the SR-Capabilities
sub-TLV including the SRGB as described in
[I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-isis-segment-routing-extensions].
o Router E advertises the prefix-SID SID(E) of prefix P(E) so MUST
also advertise the encapsulation endpoint and the tunnel type of
any tunnel used to reach E. It does this using the mechanisms
described in [I-D.ietf-isis-encapsulation-cap] or
[I-D.ietf-ospf-encapsulation-cap].
o If A and E are in different IGP areas/levels, then:
* The OSPF Tunnel Encapsulation TLV
[I-D.ietf-ospf-encapsulation-cap] or the ISIS Tunnel
Encapsulation sub-TLV [I-D.ietf-isis-encapsulation-cap] is
flooded domain-wide.
* The OSPF SID/label range TLV
[I-D.ietf-ospf-segment-routing-extensions] or the ISIS SR-
Capabilities Sub-TLV [I-D.ietf-isis-segment-routing-extensions]
is advertised domain-wide. This way router A knows the
characteristics of the router that originated the advertisement
of SID(E) (i.e., router E).
* When router E advertises the prefix P(E):
+ If router E is running ISIS it uses the extended
reachability TLV (TLVs 135, 235, 236, 237) and associates
the IPv4/IPv6 or IPv4/IPv6 source router ID sub-TLV(s)
[RFC7794].
+ If router E is running OSPF it uses the OSPFv2 Extended
Prefix Opaque LSA [RFC7684] and sets the flooding scope to
AS-wide.
* If router E is running ISIS and advertises the ISIS
capabilities TLV (TLV 242) [RFC7981], it MUST set the "router-
ID" field to a valid value or include an IPV6 TE router-ID sub-
TLV (TLV 12), or do both. The "S" bit (flooding scope) of the
ISIS capabilities TLV (TLV 242) MUST be set to "1" .
o Router A programs the FIB entry for prefix P(E) corresponding to
the SID(E) as follows:
* If the NP flag in OSPF or the P flag in ISIS is clear:
pop the top label
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* If the NP flag in OSPF or the P flag in ISIS is set:
swap the top label to a value equal to SID(E) plus the lower
bound of the SRGB of E
* Encapsulate the packet according to the encapsulation
advertised in [I-D.ietf-isis-encapsulation-cap] or
[I-D.ietf-ospf-encapsulation-cap]
* Send the packet towards the next hop NHi.
4.2. Packet Forwarding Procedures
[RFC7510] specifies an IP-based encapsulation for MPLS, i.e., MPLS-
in-UDP, which is applicable in some circumstances where IP-based
encapsulation for MPLS is required and further fine-grained load
balancing of MPLS packets over IP networks over Equal-Cost Multipath
(ECMP) and/or Link Aggregation Groups (LAGs) is required as well.
This section provides details about the forwarding procedure when
when UDP encapsulation is adopted for SR-MPLS over IP.
Nodes that are SR-MPLS capable can process SR-MPLS packets. Not all
of the nodes in an SR-MPLS domain are SR-MPLS capable. Some nodes
may be "legacy routers" that cannot handle SR-MPLS packets but can
forward IP packets. An SR-MPLS-capable node may advertise its
capabilities using the IGP as described in Section 4. There are six
types of node in an SR-MPLS domain:
o Domain ingress nodes that receive packets and encapsulate them for
transmission across the domain. Those packets may be any payload
protocol including native IP packets or packets that are already
MPLS encapsulated.
o Legacy transit nodes that are IP routers but that are not SR-MPLS
capable (i.e., are not able to perform segment routing).
o Transit nodes that are SR-MPLS capable but that are not identified
by a SID in the SID stack.
o Transit nodes that are SR-MPLS capable and need to perform SR-MPLS
routing because they are identified by a SID in the SID stack.
o The penultimate SR-MPLS capable node on the path that processes
the last SID on the stack on behalf of the domain egress node.
o The domain egress node that forwards the payload packet for
ultimate delivery.
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4.2.1. Packet Forwarding with Penultimate Hop Popping
The description in this section assumes that the label associated
with each prefix-SID is advertised by the owner of the prefix-SID is
a Penultimate Hop Popping (PHP) label. That is, the NP flag in OSPF
or the P flag in ISIS associated with the prefix SID is not set.
+-----+ +-----+ +-----+ +-----+ +-----+
| A +-------+ B +-------+ C +--------+ D +--------+ H |
+-----+ +--+--+ +--+--+ +--+--+ +-----+
| | |
| | |
+--+--+ +--+--+ +--+--+
| E +-------+ F +--------+ G |
+-----+ +-----+ +-----+
+--------+
|IP(A->E)|
+--------+ +--------+ +--------+
| UDP | |IP(E->G)| |IP(G->H)|
+--------+ +--------+ +--------+
| L(G) | | UDP | | UDP |
+--------+ +--------+ +--------+
| L(H) | | L(H) | |Exp Null|
+--------+ +--------+ +--------+
| Packet | ---> | Packet | ---> | Packet |
+--------+ +--------+ +--------+
Figure 3: Packet Forwarding Example with PHP
In the example shown in Figure 3, assume that routers A, E, G and H
are SR-MPLS-capable while the remaining routers (B, C, D and F) are
only capable of forwarding IP packets. Routers A, E, G, and H
advertise their Segment Routing related information via IS-IS or
OSPF.
Now assume that router A (the Domain ingress) wants to send a packet
to router H (the Domain egress) via the explicit path {E->G->H}.
Router A will impose an MPLS label stack on the packet that
corresponds to that explicit path. Since the next hop toward router
E is only IP-capable (B is a legacy transit node), router A replaces
the top label (that indicated router E) with a UDP-based tunnel for
MPLS (i.e., MPLS-over-UDP [RFC7510]) to router E and then sends the
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packet. In other words, router A pops the top label and then
encapsulates the MPLS packet in a UDP tunnel to router E.
When the IP-encapsulated MPLS packet arrives at router E (which is an
SR-MPLS-capable transit node), router E strips the IP-based tunnel
header and then process the decapsulated MPLS packet. The top label
indicates that the packet must be forwarded toward router G. Since
the next hop toward router G is only IP-capable, router E replaces
the current top label with an MPLS-over-UDP tunnel toward router G
and sends it out. That is, router E pops the top label and then
encapsulates the MPLS packet in a UDP tunnel to router G.
When the packet arrives at router G, router G will strip the IP-based
tunnel header and then process the decapsulated MPLS packet. The top
label indicates that the packet must be forwarded toward router H.
Since the next hop toward router H is only IP-capable (D is a legacy
transit router), router G would replace the current top label with an
MPLS-over-UDP tunnel toward router H and send it out. However, since
router G reaches the bottom of the label stack (G is the penultimate
SR-MPLS capable node on the path) this would leave the original
packet that router A wanted to send to router H encapsulated in UDP
as if it was MPLS (i.e., with a UDP header and destination port
indicating MPLS) even though the original packet could have been any
protocol. That is, the final SR-MPLS has been popped exposing the
payload packet.
To handle this, when a router (here it is router G) pops the final
SR-MPLS label, it inserts an explicit null label [RFC3032] before
encapsulating the packet in an MPLS-over-UDP tunnel toward router H
and sending it out. That is, router G pops the top label, discovers
it has reached the bottom of stack, pushes an explicit null label,
and then encapsulates the MPLS packet in a UDP tunnel to router H.
4.2.2. Packet Forwarding without Penultimate Hop Popping
Figure 4 demonstrates the packet walk in the case where the label
associated with each prefix-SID advertised by the owner of the
prefix-SID is not a Penultimate Hop Popping (PHP) label (i.e., the
the NP flag in OSPF or the P flag in ISIS associated with the prefix
SID is set). Apart from the PHP function the roles of the routers is
unchanged from Section 4.2.1.
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+-----+ +-----+ +-----+ +-----+ +-----+
| A +-------+ B +-------+ C +--------+ D +--------+ H |
+-----+ +--+--+ +--+--+ +--+--+ +-----+
| | |
| | |
+--+--+ +--+--+ +--+--+
| E +-------+ F +--------+ G |
+-----+ +-----+ +-----+
+--------+
|IP(A->E)|
+--------+ +--------+
| UDP | |IP(E->G)|
+--------+ +--------+ +--------+
| L(E) | | UDP | |IP(G->H)|
+--------+ +--------+ +--------+
| L(G) | | L(G) | | UDP |
+--------+ +--------+ +--------+
| L(H) | | L(H) | | L(H) |
+--------+ +--------+ +--------+
| Packet | ---> | Packet | ---> | Packet |
+--------+ +--------+ +--------+
Figure 4: Packet Forwarding Example without PHP
As can be seen from the figure, the SR-MPLS label for each segment is
left in place until the end of the segment where it is popped and the
next instruction is processed.
4.2.3. Additional Forwarding Procedures
Non-MPLS Interfaces: Although the description in the previous two
sections is based on the use of prefix-SIDs, tunneling SR-MPLS
packets is useful when the top label of a received SR-MPLS packet
indicates an adjacency-SID and the corresponding adjacent node to
that adjacency-SID is not capable of MPLS forwarding but can still
process SR-MPLS packets. In this scenario the top label would be
replaced by an IP tunnel toward that adjacent node and then
forwarded over the corresponding link indicated by the adjacency-
SID.
When to use IP-based Tunnel: The description in the previous two
sections is based on the assumption that MPLS-over-UDP tunnel is
used when the nexthop towards the next segment is not MPLS-
enabled. However, even in the case where the nexthop towards the
next segment is MPLS-capable, an MPLS-over-UDP tunnel towards the
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next segment could still be used instead due to local policies.
For instance, in the example as described in Figure 4, assume F is
now an SR-MPLS-capable transit node while all the other
assumptions keep unchanged, since F is not identified by a SID in
the stack and an MPLS-over-UDP tunnel is preferred to an MPLS LSP
according to local policies, router E would replace the current
top label with an MPLS-over-UDP tunnel toward router G and send it
out.
IP Header Fields: When encapsulating an MPLS packet in UDP, the
resulting packet is further encapsulated in IP for transmission.
IPv4 or IPv6 may be used according to the capabilities of the
network. The address fields are set as described in Section 3.
The other IP header fields (such as DSCP code point, or IPv6 Flow
Label) on each UDP-encapsulated segment can be set according to
the operator's policy: they may be copied from the header of the
incoming packet; they may be promoted from the header of the
payload packet; they may be set according to instructions
programmed to be associated with the SID; or they may be
configured dependent on the outgoing interface and payload.
Entropy and ECMP: When encapsulating an MPLS packet with an IP
tunnel header that is capable of encoding entropy (such as
[RFC7510]), the corresponding entropy field (the source port in
case UDP tunnel) MAY be filled with an entropy value that is
generated by the encapsulator to uniquely identify a flow.
However, what constitutes a flow is locally determined by the
encapsulator. For instance, if the MPLS label stack contains at
least one entropy label and the encapsulator is capable of reading
that entropy label, the entropy label value could be directly
copied to the source port of the UDP header. Otherwise, the
encapsulator may have to perform a hash on the whole label stack
or the five-tuple of the SR-MPLS payload if the payload is
determined as an IP packet. To avoid re-performing the hash or
hunting for the entropy label each time the packet is encapsulated
in a UDP tunnel it MAY be desirable that the entropy value
contained in the incoming packet (i.e., the UDP source port value)
is retained when stripping the UDP header and is re-used as the
entropy value of the outgoing packet.
5. IANA Considerations
This document makes no requests for IANA action.
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6. Security Considerations
The security consideration of [RFC8354] and [RFC7510] apply. DTLS
[RFC6347] SHOULD be used where security is needed on an MPLS-SR-over-
UDP segment.
It is difficult for an attacker to pass a raw MPLS encoded packet
into a network and operators have considerable experience at
excluding such packets at the network boundaries.
It is easy for an ingress node to detect any attempt to smuggle an IP
packet into the network since it would see that the UDP destination
port was set to MPLS. SR packets not having a destination address
terminating in the network would be transparently carried and would
pose no security risk to the network under consideration.
Where control plane techniques are used (as described in
Authors' Addresses it is important that these protocols are
adequately secured for the environment in which they are run.
7. Contributors
Ahmed Bashandy
Individual
Email: abashandy.ietf@gmail.com
Clarence Filsfils
Cisco
Email: cfilsfil@cisco.com
John Drake
Juniper
Email: jdrake@juniper.net
Shaowen Ma
Juniper
Email: mashao@juniper.net
Mach Chen
Huawei
Email: mach.chen@huawei.com
Hamid Assarpour
Broadcom
Email:hamid.assarpour@broadcom.com
Robert Raszuk
Bloomberg LP
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Email: robert@raszuk.net
Uma Chunduri
Huawei
Email: uma.chunduri@gmail.com
Luis M. Contreras
Telefonica I+D
Email: luismiguel.contrerasmurillo@telefonica.com
Luay Jalil
Verizon
Email: luay.jalil@verizon.com
Gunter Van De Velde
Nokia
Email: gunter.van_de_velde@nokia.com
Tal Mizrahi
Marvell
Email: talmi@marvell.com
Jeff Tantsura
Individual
Email: jefftant@gmail.com
8. Acknowledgements
Thanks to Joel Halpern, Bruno Decraene, Loa Andersson, Ron Bonica,
Eric Rosen, Jim Guichard, and Gunter Van De Velde for their
insightful comments on this draft.
9. References
9.1. Normative References
[I-D.ietf-isis-encapsulation-cap]
Xu, X., Decraene, B., Raszuk, R., Chunduri, U., Contreras,
L., and L. Jalil, "Advertising Tunnelling Capability in
IS-IS", draft-ietf-isis-encapsulation-cap-01 (work in
progress), April 2017.
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[I-D.ietf-isis-segment-routing-extensions]
Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A.,
Gredler, H., Litkowski, S., Decraene, B., and J. Tantsura,
"IS-IS Extensions for Segment Routing", draft-ietf-isis-
segment-routing-extensions-16 (work in progress), April
2018.
[I-D.ietf-ospf-encapsulation-cap]
Xu, X., Decraene, B., Raszuk, R., Contreras, L., and L.
Jalil, "The Tunnel Encapsulations OSPF Router
Information", draft-ietf-ospf-encapsulation-cap-09 (work
in progress), October 2017.
[I-D.ietf-ospf-segment-routing-extensions]
Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", draft-ietf-ospf-segment-
routing-extensions-25 (work in progress), April 2018.
[I-D.ietf-spring-segment-routing-mpls]
Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing with MPLS
data plane", draft-ietf-spring-segment-routing-mpls-13
(work in progress), April 2018.
[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>.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001,
<https://www.rfc-editor.org/info/rfc3031>.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
<https://www.rfc-editor.org/info/rfc3032>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <https://www.rfc-editor.org/info/rfc6347>.
[RFC7510] Xu, X., Sheth, N., Yong, L., Callon, R., and D. Black,
"Encapsulating MPLS in UDP", RFC 7510,
DOI 10.17487/RFC7510, April 2015,
<https://www.rfc-editor.org/info/rfc7510>.
Xu, et al. Expires December 3, 2018 [Page 14]
Internet-Draft SR-MPLS over IP June 2018
[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <https://www.rfc-editor.org/info/rfc7684>.
[RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and
U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4
and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794,
March 2016, <https://www.rfc-editor.org/info/rfc7794>.
[RFC7981] Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions
for Advertising Router Information", RFC 7981,
DOI 10.17487/RFC7981, October 2016,
<https://www.rfc-editor.org/info/rfc7981>.
[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>.
9.2. Informative References
[I-D.ietf-6man-segment-routing-header]
Previdi, S., Filsfils, C., Leddy, J., Matsushima, S., and
d. daniel.voyer@bell.ca, "IPv6 Segment Routing Header
(SRH)", draft-ietf-6man-segment-routing-header-13 (work in
progress), May 2018.
[I-D.ietf-mpls-spring-entropy-label]
Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
Shakir, R., and J. Tantsura, "Entropy label for SPRING
tunnels", draft-ietf-mpls-spring-entropy-label-11 (work in
progress), May 2018.
[RFC8354] Brzozowski, J., Leddy, J., Filsfils, C., Maglione, R.,
Ed., and M. Townsley, "Use Cases for IPv6 Source Packet
Routing in Networking (SPRING)", RFC 8354,
DOI 10.17487/RFC8354, March 2018,
<https://www.rfc-editor.org/info/rfc8354>.
Authors' Addresses
Xiaohu Xu
Alibaba
Email: xiaohu.xxh@alibaba-inc.com
Xu, et al. Expires December 3, 2018 [Page 15]
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Stewart Bryant
Huawei
Email: stewart.bryant@gmail.com
Adrian Farrel
Juniper
Email: afarrel@juniper.net
Syed Hassan
Cisco
Email: shassan@cisco.com
Wim Henderickx
Nokia
Email: wim.henderickx@nokia.com
Zhenbin Li
Huawei
Email: lizhenbin@huawei.com
Xu, et al. Expires December 3, 2018 [Page 16]
