Subject: Re: [Isis-wg] draft-ietf-isis-restart-02 question

From: mike shand <[email-masked]>
Date: Tue, 07 Jan 2003 16:07:47 +0000

At 15:04 02/01/2003 -0800, Ravindra Sunkad wrote:
>Hi,
>
>Section 4.3.1.2 (Re-starting) paragraph 2 reads
>
>"In the case of a re-starting router, none of the router's own non-
>  pseudonode LSPs are transmitted, nor are the router's own forwarding
>  tables updated while the timer T3 is running."
>
>Does this mean that own pseudonodes can be transmitted before T3 is
>cancelled or expires?

Yes, the point is that there is no propagation into pseudonodes between 
levels so all we are concerned with is whether the adjacencies have been 
established.

>
>If yes:
>     o At what point can the restarting router assume that all the
>       adjacencies on a LAN circuit have been re-established?

Well, you can never know for sure! There is no particular hurry, since the 
old LSPs are still out there. If you KNOW that the information has changed 
you should probably advertise that ASAP. The point is that you shouldn't 
prematurely issue pseudonode LSP(s) with missing information and then 
quickly replace them with information which is identical to what it was 
before the re-start.

Exactly what heuristic you use is implementation dependant.

         Mike

>Thanks,
>Ravi

_______________________________________________
Isis-wg mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/isis-wg

---

From: Les Ginsberg <[email-masked]>
Date: Mon, 13 Jan 2003 12:12:20 -0800

The distinction between when to start transmitting locally generated 
non-pseudonode LSPs vs locally generated pseudonode LSPs is based on the 
fact that the information in pseudonode LSPs is strictly adjacency 
information and therefore not dependent on redistribution of inter-level 
information. However, if the state of ISs connected to a LAN differs from 
what existed prior to restart, there is no reliable way to determine when 
the restarting router has current adjacency information. (Note: If the 
state of ISs connected to a LAN has NOT changed then the old pseudonode 
LSPs are accurate and do not need to be reissued.) Therefore, it would be 
my preference to remove the distinction between pseudonode and 
non-pseudonode LSPs in the text and have the restarting router use T3 
expiration/cancellation as the trigger to start transmitting all types of 
locally generated LSPs. Removal of the word "non-pseudonode" from the 
referenced text would accomplish that.

    Les

---

From: mike shand <[email-masked]>
Date: Tue, 14 Jan 2003 08:34:39 +0000

>referenced text would accomplish that.

That seems entirely reasonable to me. The subtle distinction between 
pseudonode and non-pseudonode is so subtle that it is both difficult and 
barely useful to exploit. It is less confusing, simply not to draw 
attention to it.

         Mike

>>Well, you can never know for sure! There is no particular hurry, since 
>>the old LSPs are still out there. If you KNOW that the information has 
>>changed you should probably advertise that ASAP. The point is that you 
>>shouldn't prematurely issue pseudonode LSP(s) with missing information 
>>and then quickly replace them with information which is identical to what 
>>it was before the re-start.
>>