Subject: Re: MPLS PWs over IP: Text for draft-ietf-pwe3-control-protocol-04.txt

From: Luca Martini <[email-masked]>
Date: Wed, 26 Nov 2003 10:49:26 -0700

Rahul,

This is a significant change , which is past the last call of the 
document. In addition to that, this design competes with other work 
already submitted to MPLS WG. The pwe3 control draft already states :
" The PSN tunnel can itself be an LSP, but it could equally well
   be an IP tunnel, a GRE tunnel, an IPsec tunnel, or any other sort of
   tunnel which can carry MPLS packets."

it is not in the scope of this document, or WG charter, to specify how 
to carry MPLS in GRE,Ipsec etc.
I believe that we should take this work   to the MPLS wg as standrads 
track draft.

Tks.
Luca

Rahul Aggarwal wrote:

>Hi Luca,
>
>Following up on the discussion on MPLS PWs over IP at the last IETF, here
>is suggested text for draft-ietf-pwe3-control-protocol-04.txt. It applies
>to section 3. Please let me know what you think.
>
>Thanks,
>rahul
>
>-------------------------------------------------------------------------------
>3. The Pseudowire Label
>
>.....
>
>So when PE1 sends a layer 2 PDU to PE2, it first pushes a PW label on
>   its label stack, thereby creating an MPLS packet.  It then (if PE1 is
>   not adjacent to PE2) encapsulates that MPLS packet in a PSN tunnel
>   header.  (If the PSN tunnel is an LSP, this is just a matter of
>   pushing on a second label.)  The PW label is not visible again until
>   the MPLS packet reaches PE2. PE2's disposition of the packet is based
>   on the PW label.
>
><Delete : (If the PSN tunnel is.....second label) >
>
>Note that the PW label must always be at the bottom of the packet's
>label stack and labels MUST be allocated from the per-platform label
>space
>
><Inserted Text Begin>
>
>If the PSN tunnel is an MPLS LSP, then putting on a PSN tunnel encapsulation
>is a matter of pushing an additional MPLS label on the packet. This
>upper MPLS label is the MPLS LSP label that causes the packet to be
>delivered to the egress of the PW i.e PE2.
>
>In order to enable MPLS PWs to be deployed when there are non-MPLS routers
>along the path between ingress and egress PE routers, it may be desirable
>to use an IP or GRE PSN tunnel. In this case MPLS-in-IP or MPLS-in-GRE
>[MPLS-OVER-IP-GRE] encapsulation is used to turn the MPLS PW packet into
>an IP packet. The IP source address will be the address of the PW ingress
>and the IP destination address will be the address of the PW egress. The
>net effect is that a MPLS PW packet gets sent through a dynamically
>created IP or GRE PSN tunnel. The egress PE decapsulates the MPLS-in-IP
>or MPLS-in-GRE packets as in [MPLS-OVER-IP-GRE] and processes the
>resulting MPLS PW packets.
>
>It may also be desirable to use an IPsec PSN tunnel [RFC2402, RFC2406] to
>enable MPLS PW packets to be carried securely over non-MPLS networks.
>One possible mechanism to achieve this is that the ingress PE creates an
>MPLS-in-IP or MPLS-in-GRE encapsulated packet, as above. If required the
>ingress PE then sets up a IPsec Security Association to the egress PE.
>Appropriate IPsec procedures are then applied generating a packet with an
>IP header followed by an IPsec header followed by MPLS-in-IP or MPLS-in-GRE
>encapsulated MPLS PW packet. The egress PE applies the necessary IPsec
>procedures to the arriving IPsec packets and recovers the contained
>MPLS-in-IP or MPLS-in-GRE packets, which are then appropriately processed.
>
><Inserted Text End>
>
>
>[MPLS-OVER-IP-GRE] "Encapsulating MPLS in IP or GRE", T. Worster,
>                   Rekhter Y., Rosen E., draft-ietf-mpls-in-ip-or-gre-03.txt
>[RFC2402] Kent, S. and R. Atkinson, "IP Authentication Header", RFC
>          2402, November 1998.
>
>[RFC2406] Kent,S. and R. Atkinson, "IP Encapsulating Security Payload
>          (ESP)", RFC 2406, November 1998.
>
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