Subject: [Isis-wg] draft-shand-isis-restart

From: Jeff Parker <[email-masked]>
Date: Fri, 10 Aug 2001 16:43:59 -0400

Mike -
	I have a comment and a couple of questions about your draft, 
http://search.ietf.org/internet-drafts/draft-shand-isis-restart-01.txt

1) There was a great deal of concern during the discussions 
   of OSPF restart and again about ISIS restart that we 
   should not restart with the routing tables from a router
   that has crashed.  However, there is still benefit in
   a proposal such as yours.  

   If a router detects memory corruption in a routing task, 
   it may wish to invalidate the route table before crashing
   so the restart mechanism is not used on reboot.  Adding
   this as a suggestion may aleviate some concerns.  
   However, a bug in the telnet task need not affect the 
   route table.  With a good memory architecture, the telnet
   task may be unable to affect the route table.

2) Assume that you are doing a controlled reboot of a router
   which takes longer than 30 seconds to reboot.  Would you 
   consider sending out hello messages that extend the hold time 
   to cover the expected reboot time?   That is, sending out
   hello messages with a hold time that matches the expected
   reboot time, rather than sticking with the previous value
   used.  

   The issue of unreliable transmission arises, but
   your scheme doesn't require everything to go perfectly
   to reduce the amount of churn.  

3) In your presentation of the draft on Wednesday, you made 
   the observation that since the CSNP was not acknowledged,
   you needed to add a bit to the restart protocol to acknowledge
   the CSNP.  

   Is the problem of the unreliable CSNP general enough that a
   general solution is called for?   There are applications 
   in bringing up p2p networks, in more restricted flooding
   topologies, etc. that would benefit from a reliable CSNP.
   The CSNP could include a sequence number, and the 
   acknowledgement could be a Hello or an SNP with the right
   sequence number.  (You could even return the CSNP rcvd)  
   Negotiating this capacity could be done dynamically in 
   hello packets, so the sender would know if it was worth
   resending the CSNP.

- jeff parker
- axiowave networks
- diagnostic: someone who doesn't believe in two gods
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