Subject: [multimob] Direct Multicast Routing & the Deployment of PIM-SM

From: "Thomas C. Schmidt" <[email-masked]>
Date: Wed, 01 Aug 2012 16:01:56 -0700

Hi all,

after Monday's presentation of PIM deployment options 
(draft-ietf-multimob-pmipv6-source), there was the discussion on further 
optimization options. In detail, the idea was raised to reach MNs not 
via their (permanent) HNP advertisements at the LMA, but directly at 
their current MAGs. The latter would require a dynamic unicast routing 
protocol in the access network.

I promised to talk to Sri about this (underlying unicast) approach. As 
expected, Sri emphasized that the PMIP WGs intentionally do *not* 
consider this a working option. The reason is that node mobility 
typically is more intense and faster than unicast routing dynamics. 
Advertising MN's HNPs throughout the access network would cause route 
pollution and convergence problems and quickly lead to inconsistencies. 
For the unicast case, this is the equivalent of pushing multicast 
mobility management into multicast routing, which we equally avoid.

Consequently, the deployment of PIM-SM in the access network (at MAGs) 
cannot be better than presented: The (MRIB) route to a (non-local) MN 
must be via its corresponding LMA, and we actually do not gain anything 
over the Proxy approach when using PIM-SM at MAGs. On the contrary, as 
we discussed on Monday, the PIM self-organization (phase transitions) 
will produce significant overhead for mobile sources (with likely 
convergence issues) why I would not opt for using PIM-SM other than in 
Phase 1.

Cheers,

Thomas
-- 

Prof. Dr. Thomas C. Schmidt
° Hamburg University of Applied Sciences                   Berliner Tor 7 °
° Dept. Informatik, Internet Technologies Group    20099 Hamburg, Germany °
° http://www.haw-hamburg.de/inet                   Fon: +49-40-42875-8452 °
° http://www.informatik.haw-hamburg.de/~schmidt    Fax: +49-40-42875-8409 °