draft-ietf-ccamp-isis-interas-te-extension-01.txt   draft-ietf-ccamp-isis-interas-te-extension-02.txt 
Network working group M. Chen Network working group M. Chen
Internet Draft Renhai Zhang Internet Draft Renhai Zhang
Expires: October 2008 Huawei Technologies Co.,Ltd Category: Standards Track Huawei Technologies Co.,Ltd
Category: Standards Track Xiaodong Duan Created: April 14, 2008 Xiaodong Duan
China Mobile Expires: October 14, 2008 China Mobile
April 10, 2008
ISIS Extensions in Support of Inter-AS Multiprotocol Label Switching ISIS Extensions in Support of Inter-AS Multiprotocol Label Switching
(MPLS) and Generalized MPLS (GMPLS) Traffic Engineering (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering
draft-ietf-ccamp-isis-interas-te-extension-01.txt
draft-ietf-ccamp-isis-interas-te-extension-02.txt
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Abstract Abstract
This document describes extensions to the ISIS (ISIS) protocol to This document describes extensions to the ISIS (ISIS) protocol to
support Multiprotocol Label Switching (MPLS) and Generalized MPLS support Multiprotocol Label Switching (MPLS) and Generalized MPLS
(GMPLS) Traffic Engineering (TE) for multiple Autonomous Systems (GMPLS) Traffic Engineering (TE) for multiple Autonomous Systems
(ASes). It defines ISIS-TE extensions for the flooding of TE (ASes). It defines ISIS-TE extensions for the flooding of TE
information about inter-AS links which can be used to perform inter- information about inter-AS links which can be used to perform inter-
AS TE path computation. AS TE path computation.
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proposed or defined in this document. proposed or defined in this document.
Conventions used in this document Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [RFC2119]. document are to be interpreted as described in RFC-2119 [RFC2119].
Table of Contents Table of Contents
1. Introduction.................................................2 1. Introduction.................................................3
2. Problem Statement............................................3 2. Problem Statement............................................4
2.1. A Note on Non-Objectives................................4 2.1. A Note on Non-Objectives................................4
2.2. Per-Domain Path Determination...........................4 2.2. Per-Domain Path Determination...........................5
2.3. Backward Recursive Path Computation.....................6 2.3. Backward Recursive Path Computation.....................6
3. Extensions to ISIS-TE........................................7 3. Extensions to ISIS-TE........................................7
3.1. Inter-AS Reachability TLV...............................8 3.1. Inter-AS Reachability TLV...............................8
3.2. TE Router ID............................................9 3.2. TE Router ID............................................9
3.3. Sub-TLV Detail.........................................10 3.3. Sub-TLV Detail.........................................10
3.3.1. Remote AS Number Sub-TLV..........................10 3.3.1. Remote AS Number Sub-TLV..........................10
3.3.2. IPv4 Remote ASBR ID Sub-TLV.......................10 3.3.2. IPv4 Remote ASBR ID Sub-TLV.......................10
3.3.3. IPv6 Remote ASBR ID Sub-TLV.......................11 3.3.3. IPv6 Remote ASBR ID Sub-TLV.......................11
3.3.4. IPv4 TE Router ID sub-TLV.........................12 3.3.4. IPv4 TE Router ID sub-TLV.........................12
3.3.5. IPv6 TE Router ID sub-TLV.........................13 3.3.5. IPv6 TE Router ID sub-TLV.........................12
4. Procedure for Inter-AS TE Links.............................13 4. Procedure for Inter-AS TE Links.............................13
4.1. Origin of Proxied TE Information.......................14 4.1. Origin of Proxied TE Information.......................14
5. Security Considerations.....................................15 5. Security Considerations.....................................14
6. IANA Considerations.........................................15 6. IANA Considerations.........................................15
6.1. Inter-AS Reachability TLV..............................15 6.1. Inter-AS Reachability TLV..............................15
6.2. Sub-TLVs for the Inter-AS Reachability TLV.............16 6.2. Sub-TLVs for the Inter-AS Reachability TLV.............15
6.3. Sub-TLVs for the IS-IS Router Capability TLV...........16 6.3. Sub-TLVs for the IS-IS Router Capability TLV...........16
7. Acknowledgments.............................................16 7. Acknowledgments.............................................16
8. References..................................................17 8. References..................................................16
8.1. Normative References...................................17 8.1. Normative References...................................16
8.2. Informative References.................................17 8.2. Informative References.................................16
Authors' Addresses.............................................18 Authors' Addresses.............................................17
Intellectual Property Statement................................18 Intellectual Property Statement................................18
Disclaimer of Validity.........................................19 Disclaimer of Validity.........................................18
Copyright Statement............................................19 Copyright Statement............................................18
1. Introduction 1. Introduction
[ISIS-TE] defines extensions to the ISIS protocol [ISIS] to support [ISIS-TE] defines extensions to the ISIS protocol [ISIS] to support
intra-area Traffic Engineering (TE). The extensions provide a way of intra-area Traffic Engineering (TE). The extensions provide a way of
encoding the TE information for TE-enabled links within the network encoding the TE information for TE-enabled links within the network
(TE links) and flooding this information within an area. The Extended (TE links) and flooding this information within an area. The Extended
IS Reachability TLV and Traffic Engineering Router ID TLV, which are IS Reachability TLV and Traffic Engineering Router ID TLV, which are
defined in [ISIS-TE], are used to carry such TE information. The defined in [ISIS-TE], are used to carry such TE information. The
Extended IS Reachability TLV has several nested sub-TLVs which Extended IS Reachability TLV has several nested sub-TLVs which
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document and [L1VPN-OSPF-AD]. document and [L1VPN-OSPF-AD].
2.2. Per-Domain Path Determination 2.2. Per-Domain Path Determination
In the per-domain method of determining an inter-AS path for an MPLS- In the per-domain method of determining an inter-AS path for an MPLS-
TE LSP, when an LSR that is an entry-point to an AS receives a Path TE LSP, when an LSR that is an entry-point to an AS receives a Path
message from an upstream AS with an ERO containing a next hop that is message from an upstream AS with an ERO containing a next hop that is
an AS number, it needs to find which LSRs (ASBRs) within the local AS an AS number, it needs to find which LSRs (ASBRs) within the local AS
are connected to the downstream AS so that it can compute a TE LSP are connected to the downstream AS so that it can compute a TE LSP
segment across the local AS to one of those LSRs and forward the PATH segment across the local AS to one of those LSRs and forward the PATH
message to it and hence into the next AS. See Figure 1 for an example: message to it and hence into the next AS. See Figure 1 for an
example:
R1------R3----R5-----R7------R9-----R11 R1------R3----R5-----R7------R9-----R11
| | \ | / | | | \ | / |
| | \ | ---- | | | \ | ---- |
| | \ | / | | | \ | / |
R2------R4----R6 --R8------R10----R12 R2------R4----R6 --R8------R10----R12
: : : :
<-- AS1 -->:<---- AS2 --->:<--- AS3 ---> <-- AS1 -->:<---- AS2 --->:<--- AS3 --->
Figure 1: Inter-AS Reference Model Figure 1: Inter-AS Reference Model
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IPv6 TE Router ID sub-TLV MUST be included if the ASBR has an IPv6 TE IPv6 TE Router ID sub-TLV MUST be included if the ASBR has an IPv6 TE
Router ID. If the ASBR does not have an IPv6 TE Router ID, the IPv4 Router ID. If the ASBR does not have an IPv6 TE Router ID, the IPv4
TE Router sub-TLV MUST be included instead. An IPv4 TE Router ID sub- TE Router sub-TLV MUST be included instead. An IPv4 TE Router ID sub-
TLV and IPv6 TE Router ID sub-TLV MAY both be present in an IS-IS TLV and IPv6 TE Router ID sub-TLV MAY both be present in an IS-IS
Router Capability TLV. Router Capability TLV.
4. Procedure for Inter-AS TE Links 4. Procedure for Inter-AS TE Links
When TE is enabled on an inter-AS link and the link is up, the ASBR When TE is enabled on an inter-AS link and the link is up, the ASBR
SHOULD advertise this link using the normal procedures for ISIS-TE SHOULD advertise this link using the normal procedures for ISIS-TE
[ISIS-TE]. When either the link is down or TE is disabled on the link, [ISIS-TE]. When either the link is down or TE is disabled on the
the ASBR SHOULD withdraw the advertisement. When there are changes to link, the ASBR SHOULD withdraw the advertisement. When there are
the TE parameters for the link (for example, when the available changes to the TE parameters for the link (for example, when the
bandwidth changes) the ASBR SHOULD re-advertise the link, but the available bandwidth changes) the ASBR SHOULD re-advertise the link,
ASBR MUST take precautions against excessive re-advertisements. but the ASBR MUST take precautions against excessive
re-advertisements.
Hellos MUST NOT be exchanged over the inter-AS link, and consequently, Hellos MUST NOT be exchanged over the inter-AS link, and
an ISIS adjacency MUST NOT be formed. consequently, an ISIS adjacency MUST NOT be formed.
The information advertised comes from the ASBR's knowledge of the TE The information advertised comes from the ASBR's knowledge of the TE
capabilities of the link, the ASBR's knowledge of the current status capabilities of the link, the ASBR's knowledge of the current status
and usage of the link, and configuration at the ASBR of the remote AS and usage of the link, and configuration at the ASBR of the remote AS
number and remote ASBR TE Router ID. number and remote ASBR TE Router ID.
Legacy routers receiving an advertisement for an inter-AS TE link are Legacy routers receiving an advertisement for an inter-AS TE link are
able to ignore it because they do not know the new TLV and sub-TLVs able to ignore it because they do not know the new TLV and sub-TLVs
that are defined in Section 3 in this document. They will continue to that are defined in Section 3 in this document. They will continue to
flood the LSP, but will not attempt to use the information received. flood the LSP, but will not attempt to use the information received.
In the current operation of ISIS TE the LSRs at each end of a TE link In the current operation of ISIS TE the LSRs at each end of a TE link
emit LSAs describing the link. The databases in the LSRs then have emit LSAs describing the link. The databases in the LSRs then have
two entries (one locally generated, the other from the peer) that two entries (one locally generated, the other from the peer) that
describe the different 'directions' of the link. This enables CSPF describe the different 'directions' of the link. This enables CSPF
to do a two-way check on the link when performing path computation to do a two-way check on the link when performing path computation
and eliminate it from consideration unless both directions of the and eliminate it from consideration unless both directions of the
link satisfy the required constraints. link satisfy the required constraints.
In the case we are considering here (i.e., of a TE link to another AS) In the case we are considering here (i.e., of a TE link to another
there is, by definition, no IGP peering and hence no bi-directional AS) there is, by definition, no IGP peering and hence no
TE link information. In order for the CSPF route computation entity bi-directional TE link information. In order for the CSPF route
to include the link as a candidate path, we have to find a way to get computation entity to include the link as a candidate path, we have
LSAs describing its (bidirectional) TE properties into the TE to find a way to get LSAs describing its (bidirectional) TE
database. properties into the TE database.
This is achieved by the ASBR advertising, internally to its AS, This is achieved by the ASBR advertising, internally to its AS,
information about both directions of the TE link to the next AS. The information about both directions of the TE link to the next AS. The
ASBR will normally generate a LSA describing its own side of a link; ASBR will normally generate a LSA describing its own side of a link;
here we have it 'proxy' for the ASBR at the edge of the other AS and here we have it 'proxy' for the ASBR at the edge of the other AS and
generate an additional LSA that describes that devices 'view' of the generate an additional LSA that describes that devices 'view' of the
link. link.
Only some essential TE information for the link needs to be Only some essential TE information for the link needs to be
advertised; i.e., the Interface Address, the Remote AS number and the advertised; i.e., the Interface Address, the Remote AS number and the
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001. Tunnels", RFC 3209, December 2001.
[ISIS] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and [ISIS] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990. dual environments", RFC 1195, December 1990.
[ISIS-TE-V3] Harrison, J., Berger, J., and Bartlett, M., "IPv6
Traffic Engineering in IS-IS", draft-ietf-isis-ipv6-te,
{work in progress}.
[ISIS-CAP] Vasseur, J.P. et al., "IS-IS extensions for advertising [ISIS-CAP] Vasseur, J.P. et al., "IS-IS extensions for advertising
router information", RFC 4971, July 2007. router information", RFC 4971, July 2007.
8.2. Informative References 8.2. Informative References
[INTER-AS-TE-REQ] Zhang and Vasseur, "MPLS Inter-AS Traffic [INTER-AS-TE-REQ] Zhang and Vasseur, "MPLS Inter-AS Traffic
Engineering Requirements", RFC4216, November 2005. Engineering Requirements", RFC4216, November 2005.
[PD-PATH] Ayyangar, A., Vasseur, JP., and Zhang, R., "A Per-domain [PD-PATH] Ayyangar, A., Vasseur, JP., and Zhang, R., "A Per-domain
path computation method for establishing Inter-domain", RFC path computation method for establishing Inter-domain", RFC
5152, February 2008. 5152, February 2008.
[BRPC] JP. Vasseur, Ed., R. Zhang, N. Bitar, JL. Le Roux, "A Backward [BRPC] JP. Vasseur, Ed., R. Zhang, N. Bitar, JL. Le Roux, "A
Recursive PCE-based Computation (BRPC) procedure to compute Backward Recursive PCE-based Computation (BRPC) procedure
shortest inter-domain Traffic Engineering Label Switched to compute shortest inter-domain Traffic Engineering Label
Paths ", draft-ietf-pce-brpc, (work in progress) Switched Paths", draft-ietf-pce-brpc, (work in progress).
[PCE] Farrel, A., Vasseur, JP., and Ash, J., "A Path Computation [PCE] Farrel, A., Vasseur, JP., and Ash, J., "A Path Computation
Element (PCE)-Based Architecture", RFC4655, August 2006. Element (PCE)-Based Architecture", RFC4655, August 2006.
[ISIS-TE] Smit, H. and T. Li, "Intermediate System to Intermediate [ISIS-TE] Smit, H. and T. Li, "Intermediate System to Intermediate
System (IS-IS) Extensions for Traffic Engineering (TE)", System (IS-IS) Extensions for Traffic Engineering (TE)",
RFC 3784, June 2004. RFC 3784, June 2004.
[ISIS-TE-V3] Harrison, J., Berger, J., and Bartlett, M., "IPv6
Traffic Engineering in IS-IS", draft-ietf-isis-ipv6-te,
(work in progress).
[GMPLS-TE] K.Kompella and Y.Rekhter, "IS-IS Extensions in Support of [GMPLS-TE] K.Kompella and Y.Rekhter, "IS-IS Extensions in Support of
Generalized Multi-Protocol Label Switching", RFC 4205, Generalized Multi-Protocol Label Switching", RFC 4205,
October 2005. October 2005.
[L1VPN-OSPF-AD] Bryskin, I., and Berger, L., "OSPF Based L1VPN Auto- [L1VPN-OSPF-AD] Bryskin, I., and Berger, L., "OSPF Based L1VPN Auto-
Discovery", draft-ietf-l1vpn-ospf-auto-discovery, (work in Discovery", draft-ietf-l1vpn-ospf-auto-discovery, (work in
progress). progress).
[BGP] Rekhter, Li, Hares, "A Border Gateway Protocol 4 (BGP-4)", [BGP] Rekhter, Li, Hares, "A Border Gateway Protocol 4 (BGP-4)",
RFC4271, January 2006 RFC4271, January 2006
 End of changes. 18 change blocks. 
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