1. MPLS WG Meeting IETF 58 Paris Detecting MPLS Data Plane Failures in Inter-AS and inter-provider Scenarios draft-nadeau-mpls-interas-lspping-00.txt Tom Nadeau George Swallow Detecting MPLS Data Plane Failures in Inter-AS and inter-provider Scenarios draft-nadeau-mpls-interas-lspping-00.txt Tom Nadeau George Swallow

2. Issues With Base LSP Ping Draft LSP ping as specified in draft-ietf-lsp-ping-*.txt does not in itself specify a protocol which will function correctly across autonomous systems (ASs) or across inter-provider boundaries for use in the Carrier of Carriers (CsC) MPLS VPN configuration. This also applies to inter-AS traffic engineering tunnels. The issue is that if an LSP ping request is lost within a remote AS or remote provider ’ s network, the reply may not have a route to return to the originator of the message. Most SPs hide local routing information (inter-AS/provider). –trace-route across provider networks –providers may wish to reject or alter the current protocol message. LSP ping as specified in draft-ietf-lsp-ping-*.txt does not in itself specify a protocol which will function correctly across autonomous systems (ASs) or across inter-provider boundaries for use in the Carrier of Carriers (CsC) MPLS VPN configuration. This also applies to inter-AS traffic engineering tunnels. The issue is that if an LSP ping request is lost within a remote AS or remote provider ’ s network, the reply may not have a route to return to the originator of the message. Most SPs hide local routing information (inter-AS/provider). –trace-route across provider networks –providers may wish to reject or alter the current protocol message.

3. For example, consider the following topology: AS1 AS2 AS3 ------------------------------- -------------------------- ---------------------------- Src PE -- P -- P – ASBR – ASBR – P – P – ASBR – ASBR – P – P – dst PE If the test message is send from Src PE to dst PE without the enhanced processing or the new TLV, the packet could traverse the network shown into AS3. If it encounters an error between the ASBR in AS3 and the first P router – say the packet is for an invalid FEC error case. In this case, the first P router would examine the packet and need to send a reply to the Src PE. However, if the Src PE is using an address for a network that is not distributed outside of AS1 (which might belong to a different provider than the addresses used in AS3), then the reply will never be forwarded back to Src PE. AS1 AS2 AS3 ------------------------------- -------------------------- ---------------------------- Src PE -- P -- P – ASBR – ASBR – P – P – ASBR – ASBR – P – P – dst PE If the test message is send from Src PE to dst PE without the enhanced processing or the new TLV, the packet could traverse the network shown into AS3. If it encounters an error between the ASBR in AS3 and the first P router – say the packet is for an invalid FEC error case. In this case, the first P router would examine the packet and need to send a reply to the Src PE. However, if the Src PE is using an address for a network that is not distributed outside of AS1 (which might belong to a different provider than the addresses used in AS3), then the reply will never be forwarded back to Src PE.

4. Solution The solution described here augments the existing LSP ping implementations, and leverages all existing LSP ping functionality as described in draft-ietf-lsp-ping-07.txt. We propose the addition of a new TLV to be included within the LSP ping request messages. This TLV requires some enhanced processing logic. The solution described here augments the existing LSP ping implementations, and leverages all existing LSP ping functionality as described in draft-ietf-lsp-ping-07.txt. We propose the addition of a new TLV to be included within the LSP ping request messages. This TLV requires some enhanced processing logic.

5. Solution (Cont) The first addition needed is a new TLV to be included within the LSP ping request messages. This TLV contains the following pieces of information Source PE Addr, Source PE AS #, Destination PE Address, stack of Last ASBR addresses seen. The first addition needed is a new TLV to be included within the LSP ping request messages. This TLV contains the following pieces of information Source PE Addr, Source PE AS #, Destination PE Address, stack of Last ASBR addresses seen.

6. Conclusions Solves a real problem. Preserves existing functionality. Solves a real problem. Preserves existing functionality.