Network Working Group K. Kompella, Ed. Request for Comments: 5307 Y. Rekhter, Ed. Obsoletes: 4205 Juniper Networks Updates: 5305 October 2008 Category: Standards Track
IS-IS Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)
Status of This Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Abstract
This document specifies encoding of extensions to the IS-IS routing protocol in support of Generalized Multi-Protocol Label Switching (GMPLS).
This document specifies extensions to the IS-IS routing protocol in support of carrying link state information for Generalized Multi- Protocol Label Switching (GMPLS). The set of required enhancements to IS-IS are outlined in [GMPLS-ROUTING]. Support for unnumbered interfaces assumes support for the "Point-to-Point Three-Way Adjacency" IS-IS Option type [ISIS-3way].
In this section, we define the enhancements to the Traffic Engineering (TE) properties of GMPLS TE links that can be announced in IS-IS Link State Protocol Data Units.
In this document, we enhance the sub-TLVs for the extended IS reachability TLV (see [ISIS-TE]) in support of GMPLS. Specifically, we add the following sub-TLVs:
Sub-TLV Type Length Name 4 8 Link Local/Remote Identifiers 20 2 Link Protection Type 21 variable Interface Switching Capability Descriptor
We further add one new TLV to the TE TLVs:
TLV Type Length Name 138 variable GMPLS-SRLG
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].
A Link Local Interface Identifier is a sub-TLV of the extended IS reachability TLV. The type of this sub-TLV is 4, and the length is 8 octets. The value field of this sub-TLV contains 4 octets of Link Local Identifier followed by 4 octets of Link Remote Identifier (see Section 2.1, "Support for Unnumbered Links", of [GMPLS-ROUTING]). If the Link Remote Identifier is unknown, it is set to 0.
The following illustrates encoding of the Value field of the Link Local/Remote Identifiers sub-TLV.
The Link Local/Remote Identifiers sub-TLV MUST NOT occur more than once within the extended IS reachability TLV. If the Link Local/Remote Identifiers sub-TLV occurs more than once within the extended IS reachability TLV, the receiver SHOULD ignore all these sub-TLVs.
The first octet is a bit vector describing the protection capabilities of the link (see Section 2.2, "Link Protection Type", of [GMPLS-ROUTING]). They are:
0x01 Extra Traffic
0x02 Unprotected
0x04 Shared
0x08 Dedicated 1:1
0x10 Dedicated 1+1
0x20 Enhanced
0x40 Reserved
0x80 Reserved
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The second octet SHOULD be set to zero by the sender, and SHOULD be ignored by the receiver.
The Link Protection Type sub-TLV MUST NOT occur more than once within the extended IS reachability TLV. If the Link Protection Type sub- TLV occurs more than once within the extended IS reachability TLV, the receiver SHOULD ignore all these sub-TLVs.
The Interface Switching Capability Descriptor is a sub-TLV (of type 21) of the extended IS reachability TLV. The length is the length of the value field in octets. The following illustrates encoding of the Value field of the Interface Switching Capability Descriptor sub-TLV.
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Switching Cap | Encoding | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max LSP Bandwidth at priority 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max LSP Bandwidth at priority 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max LSP Bandwidth at priority 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max LSP Bandwidth at priority 3 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max LSP Bandwidth at priority 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max LSP Bandwidth at priority 5 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max LSP Bandwidth at priority 6 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max LSP Bandwidth at priority 7 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Switching Capability-specific information | | (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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The Switching Capability (Switching Cap) field contains one of the following values:
The Encoding field contains one of the values specified in Section 3.1.1 of [GMPLS-SIG].
Maximum Link State Protocol Data Unit (LSP) Bandwidth is encoded as a list of eight 4-octet fields in the IEEE floating point format [IEEE], with priority 0 first and priority 7 last. The units are bytes (not bits!) per second.
The content of the Switching Capability specific information field depends on the value of the Switching Capability field.
When the Switching Capability field is PSC-1, PSC-2, PSC-3, or PSC-4, the Switching Capability specific information field includes Minimum LSP Bandwidth and Interface MTU.
The Minimum LSP Bandwidth is encoded in a 4-octet field in the IEEE floating point format. The units are bytes (not bits!) per second. The Interface MTU is encoded as a 2-octet integer, and carries the MTU value in the units of bytes.
When the Switching Capability field is L2SC, there is no Switching Capability specific information field present.
When the Switching Capability field is TDM, the Switching Capability specific information field includes Minimum LSP Bandwidth and an indication whether the interface supports Standard or Arbitrary SONET/SDH (Synchronous Optical Network / Synchronous Digital Hierarchy).
The Minimum LSP Bandwidth is encoded in a 4-octet field in the IEEE floating point format. The units are bytes (not bits!) per second. The indication whether the interface supports Standard or Arbitrary SONET/SDH is encoded as 1 octet. The value of this octet is 0 if the interface supports Standard SONET/SDH, and 1 if the interface supports Arbitrary SONET/SDH.
When the Switching Capability field is LSC, there is no Switching Capability specific information field present.
To support interfaces that have more than one Interface Switching Capability Descriptor (see Section 2.4, "Interface Switching Capability Descriptor", of [GMPLS-ROUTING]) the Interface Switching Capability Descriptor sub-TLV MAY occur more than once within the extended IS reachability TLV.
The Shared Risk Link Group (SRLG) TLV (of type 138) contains a data structure consisting of:
6 octets of System ID 1 octet of Pseudonode Number 1 octet Flag 4 octets of IPv4 interface address or 4 octets of a Link Local Identifier 4 octets of IPv4 neighbor address or 4 octets of a Link Remote Identifier (variable) list of SRLG values, where each element in the list has 4 octets.
The following illustrates encoding of the Value field of the SRLG TLV.
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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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | System ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | System ID (cont.) | Pseudonode num| Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 interface address/Link Local Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 neighbor address/Link Remote Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Shared Risk Link Group Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ............ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Shared Risk Link Group Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The neighbor is identified by its System ID (6 octets), plus one octet to indicate the pseudonode number if the neighbor is on a LAN interface.
The least significant bit of the Flag octet indicates whether the interface is numbered (set to 1) or unnumbered (set to 0). All other bits are reserved and should be set to 0.
The length of this TLV is 16 + 4 * (number of SRLG values).
This TLV carries the Shared Risk Link Group information (see Section 2.3, "Shared Risk Link Group Information", of [GMPLS-ROUTING]).
The SRLG TLV MAY occur more than once within the IS-IS Link State Protocol Data Units.
The restarting node SHOULD follow the IS-IS restart procedures [ISIS-RESTART] and the RSVP-TE restart procedures [GMPLS-RSVP].
When the restarting node is going to originate its IS-IS Link State Protocol Data Units for TE links, these Link State Protocol Data Units SHOULD be originated with 0 unreserved bandwidth, Traffic
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Engineering Default metric set to 0xffffff. Also, if the link has LSC or FSC as its Switching Capability, then they SHOULD be originated with 0 as Max LSP Bandwidth, until the node is able to determine the amount of unreserved resources taking into account the resources reserved by the already established LSPs that have been preserved across the restart. Once the restarting node determines the amount of unreserved resources, taking into account the resources reserved by the already established LSPs that have been preserved across the restart, the node SHOULD advertise these resources in its Link State Protocol data units.
In addition, in the case of a planned restart prior to restarting, the restarting node SHOULD originate the IS-IS Link State Protocol data units for TE links with 0 as unreserved bandwidth. Also, if the link has LSC or FSC as its Switching Capability, then they SHOULD be originated with 0 as Max LSP Bandwidth. This would discourage new LSP establishment through the restarting router.
Neighbors of the restarting node SHOULD continue to advertise the actual unreserved bandwidth on the TE links from the neighbors to that node.
This document specifies the contents of GMPLS TE TLVs in IS-IS. As these TLVs are not used for SPF computation or normal routing, the extensions specified here have no direct effect on IP routing. Tampering with GMPLS TE TLVs may have an effect on the underlying transport (optical and/or SONET/SDH) network. Mechanisms to secure IS-IS Link State PDUs and/or the TE TLVs [ISIS-HMAC] can be used to secure the GMPLS TE TLVs as well.
For a discussion of general security considerations for IS-IS, see [ISIS-HMAC].
[GMPLS-ROUTING] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4202, October 2005.
Debanjan Saha Tellium Optical Systems 2 Crescent Place P.O. Box 901 Ocean Port, NJ 07757
Phone: +1 732 923 4264 EMail: dsaha@tellium.com
Vishal Sharma
EMail: v.sharma@ieee.org
Authors' Addresses
Kireeti Kompella (editor) Juniper Networks, Inc. 1194 N. Mathilda Ave Sunnyvale, CA 94089
EMail: kireeti@juniper.net
Yakov Rekhter (editor) Juniper Networks, Inc. 1194 N. Mathilda Ave Sunnyvale, CA 94089
EMail: yakov@juniper.net
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