Unified Identifier in IPv6 Segment Routing Networks
draft-mirsky-6man-unified-id-sr-05
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
|
|
|---|---|---|---|
| Authors | Weiqiang Cheng , Greg Mirsky , Shaofu Peng , Aihua Liu , XiaoLan Wan , Cheng Wei , Shay Zadok | ||
| Last updated | 2020-02-20 (Latest revision 2019-11-04) | ||
| RFC stream | (None) | ||
| Formats | |||
| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-mirsky-6man-unified-id-sr-05
Network C. Weiqiang
Internet-Draft China Mobile
Intended status: Standards Track G. Mirsky
Expires: August 22, 2020 ZTE Corp.
P. Shaofu
L. Aihua
ZTE Corporation
W. Xiaolan
New H3C Technologies Co. Ltd
C. Wei
Centec
S. Zadok
Broadcom
February 19, 2020
Unified Identifier in IPv6 Segment Routing Networks
draft-mirsky-6man-unified-id-sr-05
Abstract
Segment Routing architecture leverages the paradigm of source
routing. It can be realized in a network data plane by prepending
the packet with a list of instructions, a.k.a. segments. A segment
can be encoded as a Multi-Protocol Label Switching (MPLS) label, IPv4
address, or IPv6 address. Segment Routing can be applied in MPLS
data plane by encoding segments in the MPLS label stack. It also can
be applied to IPv6 data plane by encoding a list of segment
identifiers in IPv6 Segment Routing Extension Header (SRH). This
document extends the use of the SRH to unified segment identifiers
encoded, for example, as MPLS label or IPv4 address, to compress the
SRH, and support more detailed network programming and interworking
between SR-MPLS and SRv6 domains.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
Weiqiang, et al. Expires August 22, 2020 [Page 1]
Internet-Draft Unified Identifier SRv6 February 2020
This Internet-Draft will expire on August 22, 2020.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document . . . . . . . . . . . . 3
1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3
1.1.2. Requirements Language . . . . . . . . . . . . . . . . 4
2. Segment Routing Extension Header: Benefits and Challenges . . 4
3. Unified SIDs in IPv6 Segment Routing Extension Header . . . . 4
4. The Use Case of Unified Segment Identifier . . . . . . . . . 6
4.1. Interworking Between SR-MPLS and SRv6 Using U-SID . . . . 6
5. Operations with Unified Segment Identifier . . . . . . . . . 9
5.1. Procedures of SR-MPLS over IP . . . . . . . . . . . . . . 10
5.2. Packet Forwarding . . . . . . . . . . . . . . . . . . . . 10
5.3. Control Plane in Support of Unified SID . . . . . . . . . 13
6. U-SID supporting SRv6 programming . . . . . . . . . . . . . . 14
7. Implementation Considerations . . . . . . . . . . . . . . . . 14
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
9. Security Considerations . . . . . . . . . . . . . . . . . . . 14
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
11. Normative References . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
Segment Routing architecture [RFC8402] leverages the paradigm of
source routing. It can be realized in a network data plane by
prepending the packet with a list of instructions, a.k.a. segment
identifiers (SIDs). A segment can be encoded as a Multi-Protocol
Label Switching (MPLS) label, IPv4 address, or IPv6 address. Segment
Routing can be applied in MPLS data plane by encoding 20-bits SIDs in
MPLS label stack [RFC8660]. It also can be applied to IPv6 data
Weiqiang, et al. Expires August 22, 2020 [Page 2]
Internet-Draft Unified Identifier SRv6 February 2020
plane by encoding a list of 128-bits SIDs in IPv6 Segment Routing
Extension Header (SRH) [I-D.ietf-6man-segment-routing-header].
This document extends the use of the SRH
[I-D.ietf-6man-segment-routing-header] to unified identifiers encoded
as MPLS label or IPv4 address to support more detailed network
programming and interworking between SR-MPLS and SRv6 domains.
1.1. Conventions used in this document
1.1.1. Terminology
SR: Segment Routing
SRH: Segment Routing Extension Header
MPLS: Multiprotocol Label Switching
SR-MPLS: Segment Routing using MPLS data plane
SID: Segment Identifier
IGP: Interior Gateway Protocol
DA: Destination Address
ILM: Incoming Label Map
FEC: Forwarding Equivalence Class
FTN: FEC-to-NHLFE map
OAM: Operation, Administration and Maintenance
TE: Traffic Engineering
SRv6: Segment Routing in IPv6
U-SID: Unified Segment Identifier
PSP: Penultimate Segment Popping
FIB: Forwarding Information Base
Weiqiang, et al. Expires August 22, 2020 [Page 3]
Internet-Draft Unified Identifier SRv6 February 2020
1.1.2. 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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Segment Routing Extension Header: Benefits and Challenges
Many functions related to Operation, Administration and Maintenance
(OAM) require identification of the SR tunnel ingress and the path,
constructed by segments, between the ingress and the egress SR nodes.
Combination of IPv6 encapsulation [RFC8200] and SRH
[I-D.ietf-6man-segment-routing-header], referred to as SRv6, comply
with these requirements while it is challenging when applying SR in
MPLS networks, also referred to as SR-MPLS.
On the other hand, the size of IPv6 SID presents a scaling challenge
to use topological instructions that define strict explicit traffic-
engineered (TE) path or support network programming in combination
with service-based instructions. At the same time, that is where SR-
MPLS approach provides better results due to smaller SID length. It
can be used to compress the SRv6 header size when a smaller namespace
of available SIDs is sufficient for addressing the particular
network.
SR-MPLS is broadly used in metro networks. With the gradual
deployment of SRv6 in the core networks, supporting interworking
between SR-MPLS and SRv6 becomes the necessity for operators. It is
operationally more efficient and straightforward if SRv6 can use the
same size SIDs as in SR-MPLS. The SRH can be extended to define the
same as in SR-MPLS SID length to support the unified segment
identifier (U-SID). As a result, end-to-end SR tunnel may use U-SIDs
across SR-MPLS and SRv6 domains.
3. Unified SIDs in IPv6 Segment Routing Extension Header
SRH format has been defined in Section 3 of
[I-D.ietf-6man-segment-routing-header] as presented in Figure 1
Weiqiang, et al. Expires August 22, 2020 [Page 4]
Internet-Draft Unified Identifier SRv6 February 2020
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | Routing Type | Segments Left |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Last Entry | Flags | Tag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Segment List[0] (128 bits IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
...
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Segment List[n] (128 bits IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
// Optional Type Length Value objects (variable) //
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: SRH format
This document defines a new field Size in the SRH Flags field as a
two-bits field with the following values:
0b00 - 128-bits SID, an IPv6 address.
0b01 - 32-bits SID. In some environments, the context could be of
IPv4 address, while in some other cases, it could represent an
index of list or range of IPv4/IPv6 addresses. Another
interpretation of 32-bits SID could be as a complementary element
of an IPv4/IPv6 prefix. The setting of the interpretation might
be done through the control plane based signaling and is outside
the scope of this document. If this SID represents a
complementary part of an IPv4/IPv6 prefix, the original IP address
can be re-constructed by using, for example, mapping, stitching,
shifting or translating operation. Specification of such a
mechanism is outside the scope of this document.
Weiqiang, et al. Expires August 22, 2020 [Page 5]
Internet-Draft Unified Identifier SRv6 February 2020
0b10 - 32-bits SID, which includes an MPLS label in the leftmost
20-bits as displayed in Figure 2. Information in the Context
field could be interpreted as a flavor of a particular network
programming behavior. Specification of the network programming
using this type of U-SID is outside the scope of this document.
[Ed.note. Replace with a reference to the U-SID network
programming document.]
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MPLS Label | Context |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Format of Unified SID with MPLS Label
0b11 - Reserved for future use.
Entries of the segment list in the SRH MUST be of the same length.
4. The Use Case of Unified Segment Identifier
U-SID can be used for interworking between SR-MPLS and SRv6 domains.
SR-MPLS is often used in a metro network, for example, in the
backhaul metro network of CMCC. If the core network uses SRv6, for
example, the core network of the same operator, U-SID can be used in
the SRv6 domain to interwork with SR-MPLS in the metro network to
form an end-to-end tunnel.
4.1. Interworking Between SR-MPLS and SRv6 Using U-SID
SR-MPLS uses SR SIDs as MPLS label in MPLS stack, and the SIDs are
32-bits long. SRv6 uses SR SIDs as IPv6 extension header in SRH, and
the SIDs are 128-bits long.
The U-SID uses the same 32-bits long SIDs in MPLS stack and SRH.
Thus, four 32-bits long U-SIDs can be placed in the space of a single
128-bits long header. The encapsulation is illustrated in Figure 3.
Weiqiang, et al. Expires August 22, 2020 [Page 6]
Internet-Draft Unified Identifier SRv6 February 2020
+---------+ +----------------------------------+
| | | IPv6 header |
| Ethernet| +----------------------------------+
| | | SRH |
+---------+ +----------------------------------+
| USID1 | | USID1 | USID2 | ... | USID4 |
+---------+ +----------------------------------+
| USID2 | | USID5 |... | USIDn | Null |
+---------+ +----------------------------------+
| ... | + Payload |
+---------+ +----------------------------------+
| USIDn |
+---------+
| Payload |
+---------+
Figure 3: 32-bits long U-SIDs Encapsulation
The SR-MPLS and SRv6 interworking is illustrated in Figure 4. An
end-to-end SR tunnel from A to F crosses the SR-MPLS and SRv6
domains. The SR-MPLS domain could be using IPv4 or IPv6 address
family. The SRv6 border nodes (E/G) receive SR-MPLS packets and
forward them into the SRv6 domain using an SR-MPLS Binding SID
[RFC8660].
Weiqiang, et al. Expires August 22, 2020 [Page 7]
Internet-Draft Unified Identifier SRv6 February 2020
+-----+ +-----+ +-----+ +-----+
| A +-----------+ B +-----------+ E +-----------+ F |
+-----+ +--+--+ +--+--+ +--+--+
| SR-MPLS | | SRv6 |
| | | |
+-----+ +--+--+ +--+--+ +--+--+
| C |-----------| D +-----------+ G +-----------+ H |
+-----+ +-----+ +-----+ +-----+
+--------------+
| Eth(E->G) |
+--------------+ +--------------+
| Eth(A->B) | |IPv6 DA:G.intf|
+--------------+ +--------------+ +--------------+
| USID(B) | | Eth(B->E) | |SRH |
+--------------+ +--------------+ |NH:MPLS SL:2|
| USID(E1) | | USID(E1) | |USID(ADJ E->G)|
+--------------+ +--------------+ |USID(ADJ G->H)|
| USID(E2) | | USID(E2) | |USID(ADJ H->F)|
+--------------+ +--------------+ +--------------+
| USID(F) | | USID(F) | | USID(F) |
+--------------+ +--------------+ +--------------+
|Label(service)| |Label(service)| |Label(service)|
+--------------+ +--------------+ +--------------+
| Payload | -> | Payload | -> | Payload |
+--------------+ +--------------+ +--------------+
Figure 4: SR-MPLS and SRv6 interworking
The SRv6 edge node E assigns two SIDs, e.g., E1 and E2, E1 is an SR-
MPLS Node-SID, E2 is an SR-MPLS Binding-SID, which represents an SRv6
policy (from E to F, via segment list E-G-H-F) with U-SID
encapsulation. At the headend A, the end-to-end segment list could
be B-E1-E2-F. Figure 6 demonstrates an example of the packet
forwarding, where U-SID is an MPLS label.
The controller may assign the end-to-end SR tunnel U-SIDs (from A to
F), and another method is outside the scope of this document.
The reverse interworking is illustrated in Figure 5. An end-to-end
SR tunnel from F to A crosses the SRv6 and SR-MPLS domains. The SRv6
border nodes (E/G) receive SRv6 packets and forward them into the SR-
MPLS domain using an SR-MPLS Binding SID or normal Prefix/Adjacency
SID.
Weiqiang, et al. Expires August 22, 2020 [Page 8]
Internet-Draft Unified Identifier SRv6 February 2020
+-----+ +-----+ +-----+ +-----+
| A +-----------+ B +-----------+ E +-----------+ F |
+-----+ +--+--+ +--+--+ +--+--+
| SR-MPLS | | SRv6 |
| | | |
+-----+ +--+--+ +--+--+ +--+--+
| C |-----------| D +-----------+ G +-----------+ H |
+-----+ +-----+ +-----+ +-----+
+--------------+
| Eth(F->H) |
+--------------+
|IPv6 DA:H.intf|
+--------------+
|SRH |
|NH:MPLS SL:2|
|USID(ADJ F->H)|
+--------------+ |USID(ADJ H->G)|
| Eth(E->B) | |USID(ADJ G->E)|
+--------------+ +--------------+ +--------------+
| Eth(B->A) | | USID(B) | | USID(B) |
+--------------+ +--------------+ +--------------+
| USID(A) | | USID(A) | | USID(A) |
+--------------+ +--------------+ +--------------+
|Label(service)| |Label(service)| |Label(service)|
+--------------+ +--------------+ +--------------+
| Payload | <- | Payload | <- | Payload |
+--------------+ +--------------+ +--------------+
Figure 5: SR-MPLS and SRv6 reverse interworking
The SRv6 edge node F assigns an SR-MPLS Binding-SID F2, which
represents an SRv6 policy (from F to E, via segment list F-H-G-E)
with U-SID encapsulation. At the headend F, the end-to-end segment
list could be F2-B-A.
5. Operations with Unified Segment Identifier
When SRH is used to include 32-bits long U-SIDs, the ingress and
transit nodes of an SR tunnel act as described in Section 5.1 and
Section 5.2 of [I-D.ietf-6man-segment-routing-header] respectively.
If U-SID is used to support interworking between SR-MPLS and SRv6
domains, it is beneficial that U-SID type matches to an MPLS label.
In that case, an ILM (Incoming Label Map) entry can be used to map a
U-SID to an IPv6 address. As a result, it is not necessary to
introduce a new type of index-based mapping table. For ILM entry of
Weiqiang, et al. Expires August 22, 2020 [Page 9]
Internet-Draft Unified Identifier SRv6 February 2020
Adjacency-SID, the mapping result copied to DA (Destination Address)
is the remote interface IPv6 address, for ILM entry of Node-SID, the
mapping result that is copied into DA is a remote node loopback IPv6
address.
Operations on an MPLS label of U-SID type are the same as those
defined in [RFC8663]. However, SR-MPLS over SRH has the following
advantages compared with SR-MPLS over UDP:
o SRH is flexible to extend flags or sub-TLVs for service
requirements, but UDP not.
o Labels in SRH can meet 8 bytes alignment requirements as per
[RFC8200], but UDP not.
o The source address of the SR policy is not discarded, but UDP not.
5.1. Procedures of SR-MPLS over IP
Procedures of SR-MPLS over IP of [RFC8663] described how to construct
an adjusted SR-MPLS FTN (FEC-to-NHLFE map) and ILM entry towards a
prefix-SID when next-hops are IP-only routers. The action of FTN and
ILM entry will steer the packet along an outer tunnel to the
destination node that has originated the FEC (Forwarding Equivalence
Class). UDP header is removed and put again at the each segment
endpoint. However, for SR-MPLS over SRH in this document we don't
try to depend on that adjusted FIB (Forwarding Information Base)
entry, because there are not any actions needed to get from the FIB
entry, a traditional ILM entry (maybe without out-label because of
IP-only next-hop) is enough to get the FEC information, i.e., to map
a U-SID to an IPv6 address and copy to DA. Note that an
implementation can get both FEC and next-hop/interface forwarding
information from the ILM entry, to avoid extra FIB lookup. An SRv6
policy chosen to encapsulate U-SID list within SRH is determined at
the ingress node of this SRv6 policy, SRH is preserved along the SR
to egress, though PSP (Penultimate Segment Popping) may be used, that
is different from SR-MPLS over IP/UDP method [RFC8663], so the source
address (i.e., the ingress of the SRv6 policy) is not discarded.
5.2. Packet Forwarding
U-SID based packet forwarding is similar to the processing described
in [RFC8663]. But it differs from that in FIB action and segment
list processing. For completeness, we repeat the description of
[RFC8663] with modification as follows.
Weiqiang, et al. Expires August 22, 2020 [Page 10]
Internet-Draft Unified Identifier SRv6 February 2020
+-----+ +-----+ +-----+ +-----+ +-----+
| A +-------+ B +-------+ C +--------+ D +--------+ H |
+-----+ +--+--+ +--+--+ +--+--+ +-----+
| | |
| | |
+--+--+ +--+--+ +--+--+
| E +-------+ F +--------+ G |
+-----+ +-----+ +-----+
+--------+ +--------+ +--------+
|IP(A->E)| |IP(A->G)| |IP(A->G)|
+--------+ +--------+ +--------+
|SRH | |SRH | |SRH |(or PSP)
| SL:2 | | SL:1 | | SL:0 |
| L(E) | | L(E) | | L(E) |
| L(G) | | L(G) | | L(G) |
| L(H) | | L(H) | | L(H) |
+--------+ +--------+ +--------+
| Packet | ---> | Packet | ---> | Packet |
+--------+ +--------+ +--------+
Figure 6: Packet Forwarding Example
In the example shown in Figure 6, assume that routers A, E, G, and H
are U-SID capable (i.e., both SR-MPLS and SRv6 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 an SRv6 policy with the explicit
path {E->G->H}. Router A will impose an MPLS label stack within SRH
on the packet that corresponds to that explicit path. Router A
searches ILM entry by the top label (that indicated router E), get
the FEC information and next-hop/interface forwarding information, a
loopback IPv6 address of E, and then copy to DA and sends the packet.
The value of SRH.SL is 2.
When the IPv6 packet arrives at router E, router E picks the next
segment (label) within SRH based on the SRH.SL value of 2, searches
ILM entry by the next label, get the FEC information and next-hop/
interface forwarding information, a loopback IPv6 address of G, and
then copy to DA and sends the packet. The value of SRH.SL is 1.
When the IPv6 packet arrives at router G, router G gets the next
segment (label) within SRH based on the SRH.SL value of 1, looks up
ILM entry by the next label, gets the FEC information and next-hop/
Weiqiang, et al. Expires August 22, 2020 [Page 11]
Internet-Draft Unified Identifier SRv6 February 2020
interface forwarding information, a loopback IPv6 address of H, and
then copies it to IP DA and transmits the packet. Because the value
of SRH.SL is 0, the SRH can be removed if the behavior flavor
codepoint of next segment (label) is set to PSP.
Processing of SRH with elements carrying 20 bits-long SIDs closely
follows SRH processing as defined in Section 4.3.1.1
[I-D.ietf-6man-segment-routing-header] and is demonstrated in the
pseudo-code below:
Weiqiang, et al. Expires August 22, 2020 [Page 12]
Internet-Draft Unified Identifier SRv6 February 2020
S01. When an SRH is processed {
S02. If (Segments Left == zero) {
S03. Proceed to process the next header in the packet,
whose type is identified by the Next Header field in
the Routing header.
S04. }
S05. Else {
S06. If local configuration requires TLV processing {
S07. Perform TLV processing (see TLV Processing)
S08. }
S09. max_last_entry =
( Hdr Ext Len * 8/ sizeof(SRH_element) ) - 1
S10. If ((Last Entry > max_last_entry) or
S11. (Segments Left is greater than (Last Entry+1)) {
S12. Send an ICMP Parameter Problem, Code 0, message to
the Source Address, pointing to the Segments Left
field, and discard the packet.
S13. }
S14. Else {
S15. Decrement Segments Left by 1.
S16. Use Segment List[Segments Left] as the key
in exact match lookup of FIB
S17. If (Lookup_result == Empty)
S18. Send an ICMP Destination Unreachable and
discard the packet
S19. Else {
S20. Copy Lookup_result as the destination address
of the IPv6 header.
S21. If (IPv6 Hop Limit is less than or equal <= to 1) {
S22. Send an ICMP Time Exceeded -- Hop Limit Exceeded in
Transit message to the Source Address and discard
the packet.
S23. }
S24. Else {
S25. Decrement the Hop Limit by 1
S26. Resubmit the packet to the IPv6 module
for transmission to the new destination.
S27. }
S28. }
S29. }
S30. }
S31. }
5.3. Control Plane in Support of Unified SID
The introduction of the Unified Identifier may rely on the existing
SR extensions to the routing protocols. But some enhancements in the
Weiqiang, et al. Expires August 22, 2020 [Page 13]
Internet-Draft Unified Identifier SRv6 February 2020
control plane are still required. This section references to the
existing protocols and identifies necessary extensions.
SR extensions to Interior Gateway Protocols (IGP), IS-IS [RFC8667],
OSPF [RFC8665], and OSPFv3 [RFC8666], defined how 20-bits and 32-bits
SIDs advertised and bound to SR objects and/or instructions.
Extensions to BGP Link-state address family
[I-D.ietf-idr-bgp-ls-segment-routing-ext] enabled propagation of
segment information of variable length via BGP.
6. U-SID supporting SRv6 programming
U-SID can support SRv6 programming defined by
[I-D.ietf-spring-srv6-network-programming]. The details will be
described in another document.
7. Implementation Considerations
The Unified SID solution has been already implemented and tested by
two companies:
o Centec has conducted its PoC, and the report is available at
https://cloud.tencent.com/developer/article/1540023.
o Broadcom, in its lab, also conducted PoC testing of the U-SID
solution.
8. IANA Considerations
IANA is requested to allocate from the Segment Routing Header Flags
registry the two-bits long field referred to as Size.
9. Security Considerations
This specification inherits all security considerations of [RFC8402]
and [I-D.ietf-6man-segment-routing-header].
10. Acknowledgements
TBD
11. Normative References
[I-D.ietf-6man-segment-routing-header]
Filsfils, C., Dukes, D., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", draft-ietf-6man-segment-routing-header-26 (work in
progress), October 2019.
Weiqiang, et al. Expires August 22, 2020 [Page 14]
Internet-Draft Unified Identifier SRv6 February 2020
[I-D.ietf-idr-bgp-ls-segment-routing-ext]
Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H.,
and M. Chen, "BGP Link-State extensions for Segment
Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-16
(work in progress), June 2019.
[I-D.ietf-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J., Voyer, D.,
Matsushima, S., and Z. Li, "SRv6 Network Programming",
draft-ietf-spring-srv6-network-programming-09 (work in
progress), February 2020.
[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>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[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>.
[RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing with the MPLS Data Plane", RFC 8660,
DOI 10.17487/RFC8660, December 2019,
<https://www.rfc-editor.org/info/rfc8660>.
[RFC8663] Xu, X., Bryant, S., Farrel, A., Hassan, S., Henderickx,
W., and Z. Li, "MPLS Segment Routing over IP", RFC 8663,
DOI 10.17487/RFC8663, December 2019,
<https://www.rfc-editor.org/info/rfc8663>.
[RFC8665] Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler,
H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", RFC 8665,
DOI 10.17487/RFC8665, December 2019,
<https://www.rfc-editor.org/info/rfc8665>.
Weiqiang, et al. Expires August 22, 2020 [Page 15]
Internet-Draft Unified Identifier SRv6 February 2020
[RFC8666] Psenak, P., Ed. and S. Previdi, Ed., "OSPFv3 Extensions
for Segment Routing", RFC 8666, DOI 10.17487/RFC8666,
December 2019, <https://www.rfc-editor.org/info/rfc8666>.
[RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
Extensions for Segment Routing", RFC 8667,
DOI 10.17487/RFC8667, December 2019,
<https://www.rfc-editor.org/info/rfc8667>.
Authors' Addresses
Cheng Weiqiang
China Mobile
Beijing
China
Email: chengweiqiang@chinamobile.com
Greg Mirsky
ZTE Corp.
Email: gregimirsky@gmail.com
Peng Shaofu
ZTE Corporation
No.50 Software Avenue, Yuhuatai District
Nanjing
China
Email: peng.shaofu@zte.com.cn
Liu Aihua
ZTE Corporation
Zhongxing Industrial Park, Nanshan District
Shenzhen
China
Email: liu.aihua@zte.com.cn
Weiqiang, et al. Expires August 22, 2020 [Page 16]
Internet-Draft Unified Identifier SRv6 February 2020
Wan Xiaolan
New H3C Technologies Co. Ltd
No.8, Yongjia Road, Haidian District
Beijing
China
Email: wxlan@h3c.com
Cheng Wei
Centec
Building B, No.5 Xing Han Street, Suzhou Industrial Park
Suzhou
China
Email: Chengw@centecnetworks.com
S.Zadok
Broadcom
Israel
Email: shay.zadok@broadcom.com
Weiqiang, et al. Expires August 22, 2020 [Page 17]