Subject: [Roll] Few comments for our first discussion today

From: JP Vasseur <[email-masked]>
Date: Thu, 16 Apr 2009 15:31:07 +0200

Dear all,

First many thanks again for accepting to be part of the DT. I did not  
want to comment on the various individual submissions so far since it  
was much more appropriate to provide feed-back to the DT, especially  
because the authors of these drafts are part of the DT.

Please find below some comments (that apply to the IDs already posted):

- No Layer-2 dependency: We do need to avoid any layer-2 dependency.  
It is of course fine to refer to specific optimization on 15.4 but I  
saw in some proposals assumptions that we would be using 16-bit  
identifier a la "6LoWPAN" for example: the routing protocol MUST be  
media "agnostic" (no layer dependencies). There are other areas where  
the routing mandates ACK at layer 2, which may not be available. It is  
fine to benefit from L2 related information bearing in mind that they  
may not be available, thus they should not be mandatory for the  
routing protocol to operate.
- We need to have a discussion on whether temporary (or bounded) loops  
are acceptable.
- We also need to define how to perform non shortest path selection  
(constrained based routing): label/flow switch versus source routing
- We will need to carefully consider the option of either extending  
existing IPv6 packets (e.g. ND) versus defining new packets.
- In some proposals I saw a combination of periodic refresh mechanisms  
for prefix dissemination *and* mechanism to explicitly withdraw some  
prefixes: we do not need both. The point here is that each time we  
consider several options we will need to look at the consequences in  
term of:
	* States maintenance in a router
	* Control plane traffic in the network (e.g. header overhead in case  
of source routing or loop detection for example, periodic route  
refresh, ...)
	* Manageability and Security
- Careful consideration must be given to auto-adaptative behavior.  
Since the routing protocol will adapt to a wide range of situations  
*and* considering that 0-config is a MUST from most of the routing  
requirements ID, protocol auto-adaptation (e.g. timers) is critical.

Thanks.

JP