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Background

MPLS-TP Loopback Draft draft-boutros-mpls-tp-loopback-01.txt Sami Boutros Siva Sivabalan George Swallow David Ward Rahul Aggarwal Nabil Bitar. Background. This draft specifies how to put an MPLS-TP LSP into and out-of loopback mode. This extension specifies two forms of the mode

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Background

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  1. MPLS-TP Loopback Draftdraft-boutros-mpls-tp-loopback-01.txtSami Boutros Siva Sivabalan George SwallowDavid WardRahul AggarwalNabil Bitar

  2. Background • This draft specifies how to put an MPLS-TP LSP into and out-of loopback mode. • This extension specifies two forms of the mode • Intrusive: loop all traffic (including data) or • Non-instrusive only OAM messages, not data traffic

  3. Problem Definition MPLS Bidirectional LSP LSR-1 LSR-3 LSR-2 Consider the above scenario: We have a bidirectional MPLS LSP going from LSR-1 to LSR-2 to LSR-3. LSR-1 and LSR-3 are acting as MEPs and terminating the Bidirectional MPLS-LSP and LSR-2 is acting as a MIP. Traffic would flow on the LSP from LSR-1 to LSR-3

  4. Problem Definition Continued… MPLS Bidirectional LSP LSR-1 LSR-3 LSR-2 Need to put MPLS bidirectional LSP in Loopback mode Assume we need on LSR-2 to put the LSP in Full Loopback (FLB) or OAM Loopback mode (OLB). In FLB mode, data traffic sent from LSR-1 will be looped back to LSR-1. In OLB mode, data traffic will not be looped back. In both modes, the MPLS OAM Loopback message will be received by LSR-2, and an Ack will be sent back to LSR-1.

  5. Proposed Solution : LSP into Non-Intrusive Loopback Mode MPLS Bidirectional LSP LSR-1 LSR-3 LSR-2 LSR-1 sends an OAM Loopback Request to LSR-2, the message contains the LSR-2 ID MPLS-OAM Message TTL expired at LSR-2, LSR-2 matches the ID and sends an ack back to LSR-1 • OAM intercepted at MIP obecause TTL expiry • target id used to match the MIP address • if no match, send NACK.

  6. Proposed Solution: LSP into Intrusive Loopback Mode MPLS Bidirectional LSP LSR-1 LSR-3 LSR-2 LSR-1 sends a Lock Request to LSR-3 to take the MPLS LSP out of service LSR-3 takes the MPLS-LSP out of service from dataplane and sends an Ack back to LSR-1 LSR-1 sends a Loopback Request to LSR-2 To put the MPLS LSP in Full Loopback mode LSR-2 setup dataplane to loopback traffic received on this LSP from LSR-1 and sends an ack back to LSR-1

  7. Proposed Solution: Intrusive Loopback Mode, flow of data packets MPLS Bidirectional LSP LSR-1 LSR-3 LSR-2 LSR-1 sends data packets on the MPLS Bidirectional LSP to test connectivity up to LSR2, Packets may contain a sequence #’s. LSR-2 Loops back the packets sent to LSR-1 LSR-1 could check sequence #’s on packet received to guarantee no losses

  8. Proposed Solution: Out-of Intrusive Loopback Mode MPLS Bidirectional LSP LSR-1 LSR-3 LSR-2 LSR-1 sends a Loopback removal Request to LSR-2 LSR-2 setup dataplane to remove the Loopback On the MPLS LSP and sends an Ack back to LSR-1 LSR-1 sends an unLock Request to LSR-3 To put the MPLS LSP back in Service LSR-3 puts the MPLS LSP back in service and sends an ack back to LSR-1

  9. Putting MPLS-TP in Loopback using NMS An operator should be able to provision any given LSR to: • Lock/Unlock any MPLS-TP LSP. • Setup any MPLS-TP LSP in loopback mode (either FLB or OLB). • Send MPLS OAM packets from a MEP and notify NMS when MPLS OAM response arrives. When NMS is used to provision any of the above the functionality, the corresponding MPLS OAM message is not used.

  10. Proposed Solution MPLS OAM Message extensions The proposed mechanism is based on a set of new TLVs which can be transported using one of the following methods: • Using in-band MPLS OAM messages which are forwarded as MPLS packets (non-IP based). • Using LSP-Ping messages where IP/UDP packets are used (IP-based) in compliance with RFC 4379.

  11. Proposed Solution new ACH codepoint for in-band option. The ACH with "MPLS-TP Looback" code point (TBD) indicates the message type A 32-bit field is added to carry the message ID 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0 1 |0 0 0 0 |0 0 0 0 0 0 0 0 | 0xHH (MPLS-TP Loopback) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message ID | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: MPLS-TP OAM Message Header

  12. Proposed Solution new TLVs to be added.. • Lock Request TLV • Unlock Request TLV • Loopback Request TLV (with a flag saying FLB or OLB) • Loopback Removal TLV • Authentication TLV • Source Identifier TLV (not need in IP MPLS-OAM message version). • In compliance with RFC 4379 • Target Identifier TLV (needed to verify that the Loopback OAM message is meant for this node). • In compliance with RFC 4379 • Response TLV

  13. LSPV option control packet 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 • +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ • | MPLS Label Stack for the MPLS-LSP … | • +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ • | Label with EOS bit set | • +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ • | IP Hdr | • +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ • | UDP Hdr | • +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ • | TLV’s … | • +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ • Compliant with RFC 4379, 5085, draft-ietf-pwe3-ms-pw-requirements-07 • cc_type used at MEP & MIP • CW, RA and TTL cc_type at MEP • Only TTL at MIP • Reply can come back as IP or MPLS.

  14. In-band Option control packet 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MPLS Label Stack for the MPLS-LSP … | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label with EOS bit set | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0 1 |0 0 0 0 |0 0 0 0 0 0 0 0 | 0xHH (MPLS-TP Loopback) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message ID | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV’s … | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The assumption is that LSP is bidirectional or moral equivalent

  15. Optional data packet extension in Intrusive mode • In FLB mode, data packets looped back to TX MEP. • Packets may contain a sequence-id to insure order 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MPLS Label stack | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label with EOS bit set | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Optional Sequcence-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  16. Future Enhancements • Clarify LSP-Ping usage as it MUST be supported • Add code point to loop OAM packets in OLB mode. • Make Lock a MUST in FLB mode. • GAL used to allow OAM control packets to pass through the LSR that loops back packets in FLB mode. • Optional (TBD): Set of functions for the data packets, to measure delay, packet loss, etc.

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