[lisp] LISP Interworking: Proxy Egress Tunnel Routers

["Darrel Lewis (darlewis)" <[e-mail]>]

LISPers,

The WG chairs have asked me reopen discussion on Proxy Egress Tunnel
Routers.  We have discussed them on the WG list, and they were also
talked about during the presentation around "LISP Deployment" by
Margaret and Myself.

To review, a Proxy Egress Tunnel Router is a LISP Network Element that
would decapsulate traffic destined to non-LISP sites on behalf of a
given LISP site.  Proxy Egress Tunnel Routers are not directly related
to Proxy Ingress Tunnel Routers.  Instead, they allow an particular ITR
to encapsulate packets it normally would forward un-encapsulated.  These
packets would normally be forwarded by the ITR un-encapsulated.

   There are two primary reasons why sites would want to utilize a PETR:

   Avoiding strict uRPF failures:  Some provider's access networks
      require the source of the packets emitted to be within the
      addressing scope of the access networks.

   Traversing a different IP Protocol:  A LISP site may want to transmit
      packets to a non-LISP site where the some of the intermediate
      network does not support an IP protocol (v4 or v6).  PETRs can
      allow this LISP site's data to 'hop over' this by utilizing LISP's
      support for mixed protocol encapsulation.

Are there any objections to including text for Proxy Egress Tunnel
Routers to the Interworking Draft?  Both of these cases are evident in
the existing LISP beta network, and we have implementation experience
showing that they are both possible and fairly straightforward to
deploy.

-Darrel