Title: MPLS-TP Loopback Draft draft-boutros-mpls-tp-loopback-01.txt Sami Boutros Siva Sivabalan George Swallow David Ward Rahul Aggarwal Nabil Bitar
1MPLS-TP Loopback Draftdraft-boutros-mpls-tp-loopb
ack-01.txtSami Boutros Siva Sivabalan George
SwallowDavid WardRahul AggarwalNabil Bitar
2Background
- 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
3Problem 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
4Problem 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.
5Proposed 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.
6Proposed 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
7Proposed 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
8Proposed 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
9Putting 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.
10Proposed 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.
11Proposed 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
12Proposed 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
13LSPV 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.
14In-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
15Optional 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
- -----------------------
---------
16Future 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.