SPRING WG Ting. Liao
Internet-Draft Ting. Ao
Intended status: Standards Track ZTE Corporation
Expires: April 21, 2016 October 19, 2015
SPRING IPv6 ListID Encapsulation
draft-lt-6man-sr-listid-encapsulation-00.txt
Abstract
Segment Routing allows a node to steer a packet through an ordered
list of instructions, called segments. The ingress node prepends a
SR header to a packet containing a set of "segments". A segment can
represent any instruction topological or service-based. Segment
Routing can be applied to the IPv6 architecture, with a new type of
routing extension header. A segment is encoded as an IPv6 address.
An ordered list of segments is encoded as an ordered list of IPv6
addresses in the routing extension header. The segment to process is
indicated by a pointer in the routing extension header. Upon
completion of a segment, the pointer is incremented. This document
describes how to decrease the length of the IPv6 list with ListID
carried.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 21, 2016.
Copyright Notice
Copyright (c) 2015 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Abbreviations . . . . . . . . . . . . . . . . 2
3. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1.1. SLID Encapsulating . . . . . . . . . . . . . . . . . 4
3.1.1.1. A new type of Routing Extension Header . . . . . 4
3.1.1.2. R-flags defined in draft-previdi-6man-segment-
routing-header to identify . . . . . . . . . . . 4
3.1.2. SLID Forwarding . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Segment Routing can be applied to the IPv6 data plane with the
addition of a new type of Routing Extension Header as described in
[I-D.previdi-6man-segment-routing-header]. A segment is encoded as
an IPv6 address. An ordered list of segments is encoded as an
ordered list of IPv6 addresses in the routing extension header.
There may be many specified nodes or links included in the path based
on policy, each ipv6 address is 128 bits, this will greatly increase
the length of header. This document describes a method by mapping a
segment list to a ListID and carrying the ListID in the header. It
will decrease the length of the segment routing header.
2. Conventions and Abbreviations
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119] .
The following notations and abbreviations are used throughout this
draft.
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SR:Segment Routing SID:Segment Identifier SLID: Segment List
Identifier, a segment list is identified by a Segment list ID (SLID).
3. Solution
In this document, we define the Segment List Identifier (SLID). The
segment list is identified by a Segment list ID (SLID). Segment list
ID (SLID) is allocated by the controller. The segment list and the
SLID can be advertised to the related nodes. When the node receives
the mapping message, it generates a mapping table about the SLID to
the Segment List. The segment routing header could be a new type of
Routing Extension Header, or be identified by the R-flags as defined
in [I-D.previdi-6man-segment-routing-header].
3.1. Example
As shown in the figure 1.
__ +----------------------+
/ _ | Controller | __
/ / +----------------------+_ \
/ / | | | | | \ \ \
/ / | | | | | \ \ \
+---+ / +---+ | | +---+ | +---+ \ \+---+
-------- |R1 |---/---|R3 |--|---|--|R5 |---|-|R7 |---\-- |R9 |
+---+ / +---+ | | +---+ | +---+ \ +---+
| / | / \ | \ | \ |
| / | / \ | \ | \ |
+---+ +---+ +---+ +---+ +---+
|R2 |-------|R4 |--------|R6 |-----|R8 |-------|R10|-----------
+---+ +---+ +---+ +---+ +---+
Figure 1 Scenario 1
In this example, we assumes that: o All nodes are SR capable. o Each
SR node has a global IPv6 address configured by operator to identify
the node. o The operator (likely via the SDN Controller) as
provisioned the Node-SIDs 2001::1001, 2001::1002, 2001::1003,
2001::1004, 2001::1005, 2001::1006, 2001::1007, 2001::1008,
2001::1009,and 2001::1010 respectively at nodes R1, R2, R3, R4, R5,
R6, R7, R8, R9 and R10. o The controller computes a list for: {R1,
R2, R4, R3, R5, R6, R8, R7, R9, and R10}, and allocates an unused ID
2001::1100 to identify the segment list. o The controller advertises
the mapping Segment list ID (SLID) 2001::1100 for segment list {R1,
R2, R4, R3, R5, R6, R8, R7, R9, and R10} to all the nodes in the
list. o Each node receives the mapping message, generates the
mapping table of the SLID to the List.
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3.1.1. SLID Encapsulating
3.1.1.1. A new type of Routing Extension Header
A new type of Routing Extension Headers is shown in the figure 2.
The ingress node could encapsulate frames with SLID carried.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Segment List ID (128 bits ipv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2 A new type of Routing Extension Header
o Next Header: 8-bit selector. Identifies the type of header
immediately following the SRH. o Hdr Ext Len: 8-bit unsigned
integer, is the length of the SRH header in 8-octet units, not
including the first 8 octets. o Routing Type: TBD, to be assigned by
IANA. o Segments Left: It is optional, as defined in [RFC2460], it
contains the index, in the Segment List, of the next segment to
inspect. Segments Left is decremented at each segment in the list.
o RESV: Reserved and for future use. o Segment List ID: 128 bit IPv6
addresses identifying the Segment List. Used to look up the next
hop, and then the next hop exchanges the destination of the IPv6
encapsulation.
3.1.1.2. R-flags defined in draft-previdi-6man-segment-routing-header
to identify
As the R-flags have reserved and defined in
[I-D.previdi-6man-segment-routing-header], such as one of R-flags
set, it means the SLID instead of the Segment List[n] carrying in the
encapsulation, there is no need to carry the segment
list[0]...segment list[n] in this solution.
3.1.2. SLID Forwarding
As each node receives the mapping message, each node knows which one
is the next node of itself. Such as R1 receives the message of
Segment list ID (SLID) 2001::1100 mapping to the segment list {R1,
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R2, R4, R3, R5, R6, R8, R7, R9, and R10}, R1 will know R2 is my next
segment in the LIST, and when some packets need to forward on the
path of this list, it encapsulates the packet with the SLID
2001::1100 carried, the destination of the packet is the addresses of
R2 which is the next segment of R1.
When the packet transit to R2, with the next header is routing
extension header, and the routing extension header is the type of
SLID carried, or the SRH carried with the R-flags to identify the
SLID carried. R2 learns the SLID 2001::1100 mapping to the segment
list {R1, R2, R4, R3, R5, R6, R8, R7, R9, and R10}, and the next
segment of R2 in this list is R4. R2 changes the destination of this
packet with the address of R4, and then the packet transits to R4.
R4 knows R3, changes the destination,and the packet transits to R3.
... and then R10 receives the packet, it knows itself is the last
segment in the list, and decapsulates the IPv6 SR header.
4. Security Considerations
TBD.
5. Acknowledgements
In progress.
6. IANA Considerations
TBD.
7. Normative References
[I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Decraene, B., Litkowski, S.,
and r. rjs@rob.sh, "Segment Routing Architecture", draft-
ietf-spring-segment-routing-06 (work in progress), October
2015.
[]
Previdi, S., Filsfils, C., Field, B., Leung, I., Linkova,
J., Kosugi, T., Vyncke, E., and D. Lebrun, "IPv6 Segment
Routing Header (SRH)", draft-previdi-6man-segment-routing-
header-08 (work in progress), October 2015.
[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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[RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
RFC 4915, DOI 10.17487/RFC4915, June 2007,
<http://www.rfc-editor.org/info/rfc4915>.
[RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
S. Shaffer, "Extensions to OSPF for Advertising Optional
Router Capabilities", RFC 4970, DOI 10.17487/RFC4970, July
2007, <http://www.rfc-editor.org/info/rfc4970>.
[RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The
OSPF Opaque LSA Option", RFC 5250, DOI 10.17487/RFC5250,
July 2008, <http://www.rfc-editor.org/info/rfc5250>.
Authors' Addresses
Ting Liao
ZTE Corporation
No.50 Software Avenue
Nanjing, Jiangsu 210012
China
Phone: +86 25 88016576
Email: liao.ting@zte.com.cn
Ting Ao
ZTE Corporation
No.889 Bibo Rd
Shanghai 201203
China
Phone: +86 21 68897642
Email: ao.ting@zte.com.cn
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