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MLN Multi-Layer Networks

MLN Multi-Layer Networks. CCAMP WG, IETF 68 March 2007. MLN document set. Requirements. draft-ietf-ccamp-gmpls-mln-reqs-02. Analysis. draft-ietf-ccamp-gmpls-mln-eval-02. GMPLS Protocol Extensions. draft-papadimitriou-ccamp-gmpls-mrn-extensions-03 draft-ietf-ccamp-mpls-graceful-shutdown

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MLN Multi-Layer Networks

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  1. MLNMulti-Layer Networks CCAMP WG, IETF 68 March 2007

  2. MLN document set Requirements draft-ietf-ccamp-gmpls-mln-reqs-02 Analysis draft-ietf-ccamp-gmpls-mln-eval-02 GMPLS Protocol Extensions draft-papadimitriou-ccamp-gmpls-mrn-extensions-03 draft-ietf-ccamp-mpls-graceful-shutdown draft-ietf-ccamp-lsp-hierarchy-bis

  3. Analysis Summary • Four areas, where extensions of GMPLS protocols and procedures are required, have been identified • GMPLS signaling extension for the setup/deletion of virtual TE-links • GMPLS routing and signaling extension for graceful TE-link deletionAli, Z., Zamfir, A., "Graceful Shutdown in MPLS Traffic Engineering Network", <draft-ietf-ccamp-mpls-graceful-shutdown>, work in progress. • GMPLS signaling extension for constrained multi-region signaling (SC inclusion/exclusion) • GMPLS routing extension for the advertisement of the internal adaptation capability of hybrid nodes.

  4. Solution doc • Currently three protocol extensions defined • Routing extensions for the advertisement of the Internal Adaptation Capabilities: • IACD sub-TLV to be carried within the ISIS Extended IS Reacheability TLV or the OPSF Link TLV • Signaling extensions for SC inclusion exclusion • A new SC subobject to be carried within the ERO and XRO

  5. Detailed analysis of virtual TE link function • Two approaches • Soft-FA: LSP signaled but data plane resources not committed => Could rely on procedures similar to secondary LSPs (shared meshed restoration) • Remote Association: LSP not signaled, TE link ids and parameters exchanged between FA end-points => Could rely on extensions to the Call procedure (with Notify messages) • Pros and cons are discussed • Soft FA: More admission control capabilities, but scalability limitations • Remote Association: Scales well but less admission control

  6. Received comments • We privately received comments in two areas. • Path diversity / SRLG inheritance • Directionality of adaptation information • Whether it is from "first SC" to "second SC" or from "second SC" to "first SC" is determined based on SC hierarchy: Network element ............................. : -------- : : | PSC | : Link1 -------------<->--|#a | : : +--<->---|#b | : : | -------- : TDM : | ---------- : +PSC : +--<->--|#c TDM | : Link2 ------------<->--|#d | : : ---------- : :............................ Figure 5a. Hybrid node.

  7. Next step • Two documents are close to WG last call. • Critical review and comments are appreciated. • We propose to WG last call after another spin. • We propose to solution doc as WG doc • SC incl/excl, adaptation, and virtual TE-link, 2007 2008 10 1 4 7 10 1 3 ietf 68 ietf 69 ietf 70 ietf 71 Requirements WG Last call 02 03 Evaluation WG Last cal 02 03 SC incl/excl, AdvrAdaptCap, Virtual TE-link Solution WG Last call 03 04 00 01 graceful TE-link shutdown 02 hierarchy-bis 01 02

  8. Backup slides

  9. Virtual TE-link • Two approaches: • Soft FA approach: FA-LSP established in the control plane without actually activating cross connections in the data plane. • requires state maintenance on all transit LSRs (N square issue) • allows for admission control • Soft-FA LSPs may be setup using procedures similar to GMPLS P&R procedures for setting up secondary LSPs • Remote Association approach: No end-to-end signaling. Exchange of virtual TE-links ids and parameters directly between TE- link end points. • does not require state maintenance on transit LSRs, but reduces admission control capabilities • association between Virtual TE-link end-points may be based on extensions to the RSVP-TE Call procedure

  10. Graceful TE-link deletion • When a TE-link deletion is planned, we want to gracefully disable Traffic Engineering on the TE Link to avoid traffic disruption. • The impact on the traffic flows carried over the TE-link is minimized by triggering notifications so as to gracefully reroute such flows before the TE-link is deleted. • Disabling the resource in the control plane and removing the resource for forwarding. • The node initiating the graceful shutdown condition SHOULD delay the removal of the resources for forwarding. • The control plane should gracefully divert the traffic away from the resource being gracefully shutdown. • Two approaches: • RSVP-TE Signaling Mechanism • Path-Error or Notify is used with “local link maintenance on TE Link required” to convey the information to the LSRs along the TE-link and not to all nodes in the network. • OSPF/ ISIS Mechanisms • Originate the TE LSA/LSP with Traffic Engineering metric set to 0xffffffff, 0 as unreserved bandwidth/Max LSP bandwidth to discourage all nodes in the area to establish new LSPs through the TE-link. • Ali, Z., Zamfir, A., "Graceful Shutdown in MPLS Traffic Engineering Network", <draft-ietf-ccamp-mpls-graceful-shutdown>, work in progress.

  11. ISC inclusion/exclusion • Applying FA creation procedure [RFC 4206] in MRN environments can lead to setup one-hop FA-LSPs between each node • Extensions to existing RSVP-TE procedures are required e.g. indication of these SC values in a new sub-object of the eXclude Route Object (XRO) • Such information can be specified by explicitly indicating which SCs have to included or excluded before initiating the procedure described • This solves ambiguous selection of SC to be used along a given segment of the path (and provides possibility to optimize resource usage on a multi-region basis) 2 5 D1 link terminates PSC_1 only S 0 1 3 6 8 link terminates PSC_2 + LSC 4 7 D2 • Outgoing explicit route from node S: [0,1,3,6,8,D1] to setup PSC_2 LSP from S to D1 • At node 0: route selection is PSC_2 LSP [1,3,6,8,D1] • At node 1: solution scope for route selection is either LSC LSP [3] [3,6], [3,6,8] or [3,6,8,D1] before continuing PSC_2 LSP signaling

  12. L2SC HO-SDH OTH Fiber 1 Fiber 1 Fiber N Fiber N Adaptation capability • ISCD alone does not allow remote LSR to deduce intermediate termination capabilities of Multiple SC systems => Termination issues (blocking case) • Introduction of Interface Adaptation Capability Descriptor (IACD) • As part of TE Link_1 advertisement • ISCD sub_TLV 1 for L2SC • ISCD sub_TLV 2 for HO-SDH • ISCD sub_TLV 3 for OTH • IACD sub_TLV 1 for L2SC to HO-SDH • if no bundling of [1…N] • As part of TE Link_N advertisement • ISCD sub_TLV 1 for L2SC • ISCD sub_TLV 2 for HO-SDH • ISCD sub_TLV 3 for OTH • IACD sub_TLV 1 for L2SC to HO-SDH

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