Subject: [lisp] Issue Title (number): LISP-TE and ETR(63)

From: Darrel Lewis <[email-masked]>
Date: Tue, 20 Jul 2010 14:08:44 -0700

Issue Title (number): LISP-TE and ETR(63)
Draft Section: 8.3
Issue Description: General LISP-TE issues
Comments:

This is part of Comment 38

Section 8.2

    Note that more than one CE router at a site can be configured with
    the same IP address. In this case an RLOC is an anycast address. This
    allows resilience between the CE routers. That is, if a CE router
    fails, traffic is automatically routed to the other routers using the
    same anycast address. However, this comes with the disadvantage where
    the site cannot control the entrance point when the anycast route is
    advertised out from all border routers.

The above means that at the minimum the price of resilience between
the CE routers is the inability to support traffic engineering?
Specifically, the ISP loses any influence over the choice of which ETR
should be used to reach the multi-homed enterprise.

Moreover, if CEs are xTRs and use anycast addresses, then RLOCs are
anycast addresses as well, and thus can not be topologically
significant. Thus if an enterprise is multi-homed to two (or more)
ISPs, then use of anycast addresses for CEs would require to route
such addresses as /32 throughout the whole Internet.

Also, if anycast addresses are used as RLOCs, then how would one
deal with a situation where initially both ETR1 and ETR2 advertise
10.1.1/24 and 10.1.2/24, ITR1 routes traffic for 10.1.1.1 to ETR1, but
then ETR1, while still being up, loses connectivity to 10.1.1/24?

Response:

Dear Yakov-

Thank you for your contribution to draft-ietf-lisp-06.txt. The draft authors
have reviewed your comments but do not feel that changes to the document are
warranted at this time. We do however feel that this information could be very
useful in a 'deployment guide' or 'uses' type draft document.  Please feel
free to continue discussion of your issue on the LISP working group mailing
list, [email-masked]. Should discussion result in WG consensus that changes
are required, the authors will incorporate appropriate text into a future
version of the draft.

	Thanks!
	Darrel, for the LISP document authors