Internet DRAFT - draft-chen-isis-source-identifier-distribution
draft-chen-isis-source-identifier-distribution
Network Working Group M. Chen
Internet-Draft Huawei
Intended status: Standards Track G. Mirsky
Expires: April 16, 2015 Ericsson
October 13, 2014
Extensions to ISIS for Source Identifier Distribution
draft-chen-isis-source-identifier-distribution-00
Abstract
A Source Identifier (SI) is carried in an MPLS Source Label and used
to identify (one of) the ingress LSR(s) to a specific LSP. This
document defines extensions to ISIS protocol for distribution of the
mapping of a Source Identifier to an specific LSR. Therefore, the
egress and intermediate LSRs can use the SI to determine from which
LSR an MPLS packet is sent.
This document also defines ISIS extensions to advertise the Source
Label Capability (SLC) of each LSR that indicates whether an LSR can
properly process the Source Label Indicator (SLI) special purpose
label and Source Label (SL). With the SLC, an ingress LSR can
determine whether it is allowed to insert a SL into the label stack
for a specific LSP.
Requirements Language
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 RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 16, 2015.
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Copyright Notice
Copyright (c) 2014 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. Extensions to ISIS . . . . . . . . . . . . . . . . . . . . . 3
3. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
As defined in [I-D.chen-mpls-source-label], a Source Identifier (SI)
is a number in the range of [16, 65535]. Each node in a domain will
be allocated one or more unique SIs. A SI is carried in an
MultiProtocol Label Switching (MPLS) Source Label (SL) and used to
identify (one of) the ingress Label Switching Router (LSR) to a
specific Label Switched Path (LSP).
To identify from where an MPLS packet is sent, the egress/
intermediate LSRs need to know to which ingress LSR a SI is
correlated. Therefore, a mechanism to distribute the correlation of
a SI to its correlated LSR is required.
In addition, for an ingress LSR, before inserting a SL in the label
stack of an LSP, it needs to know whether the egress LSR has the
capability to process the SLI and SL, otherwise the packet will be
dropped at the egress LSR. The capability is called Source Label
Capability (SLC).
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This document defines extensions to ISIS [RFC1195] protocol to
distribute SI to LSR mapping and advertise the SLC of each LSR.
2. Extensions to ISIS
The Source Identifier sub-TLV is used to distribute the SI(s) to LSR
mapping and the SLC. The Source Identifier sub-TLV is advertised
within an IS-IS CAPABILITY TLV that is defined in [RFC4971], it has
the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| System ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| System ID(cond.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Source Identifier 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Source Identifier n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1 - ISIS Source Identifier sub-TLV format
The value of "Type" field is TBD1.
The "Length" field defines the length of the Reserved and Source
Identifier fields in octets, which excludes the System ID field.
Each "Source Identifier" field (20 bits) contains a SI that
identifies the advertising LSR.
The "Reserved" field MUST be set to zero when sending and MUST be
ignored when received.
3. Elements of Procedure
The Source Identifier sub-TLV is carried within an IS-IS CAPABILITY
TLV that is defined in [RFC4971]. All the procedures that defined in
[RFC4971] are inherited here.
The flooding scope of the Source Identifier sub-TLV can be either
area local or entire IGP domain. The flooding scope is controlled by
the S flag in the IS-IS Router Capability TLV [RFC4971]. If the
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flooding scope is area local, the Source Identifier sub-TLV MUST be
carried within an IS-IS Router Capability TLV with the S flag clear.
If the flooding scope is the entire IGP domain, the Source Identifier
sub-TLV MUST be carried within an IS-IS Router Capability TLV with
the S flag set.
The Source Identifier sub-TLV is an optional sub-TLV. Upon receipt
the sub-TLV, a router will silently ignore the sub-TLV as defined in
[RFC4971] if it does not support it. If Source Identifier sub-TLV is
not present that MUST be interpreted as signaling of non-support of
SLC by the LSR. Presence of a Source Identifier sub-TLV MUST be
interpreted as support of SLC by the LSR. A Source Identifier sub-
TLV MUST appear only one time in an LSP. When received, only first
Source Identifier sub-TLV is valid, subsequent Source Identifier sub-
TLVs MUST be ignored.
4. IANA Considerations
IANA is requested to assign a new sub-TLV code point for the Source
Identifier sub-TLV carried within the IS-IS Router Capability TLV.
Type Value TLV Name Reference
---------- ------------------ --------------
TBD1 Source Identifier (this document)
5. Security Considerations
TBD.
6. Acknowledgements
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4971] Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate
System to Intermediate System (IS-IS) Extensions for
Advertising Router Information", RFC 4971, July 2007.
7.2. Informative References
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[I-D.chen-mpls-source-label]
Chen, M., Xu, X., Li, Z., Fang, L., and G. Mirsky,
"MultiProtocol Label Switching (MPLS) Source Label",
draft-chen-mpls-source-label-05 (work in progress), July
2014.
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990.
Authors' Addresses
Mach(Guoyi) Chen
Huawei
Email: mach.chen@huawei.com
Greg Mirsky
Ericsson
Email: Gregory.mirsky@ericsson.com
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