MPLS-TP Loopback Draft draft-boutros-mpls-tp-loopback-01.txt Sami Boutros Siva Sivabalan George Swallow David Ward Rahul Aggarwal Nabil Bitar

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

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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
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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.
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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.

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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
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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
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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
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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.

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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.

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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
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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

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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
  
• -----------------------
  ---------
• 
  TLVs
  
• -----------------------
  ---------
• 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.

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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
-------------------------
-------
TLVs
------------
-------------------- The
assumption is that LSP is bidirectional or moral
equivalent
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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
  
• -----------------------
  ---------

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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.