Subject: RE: [Isis-wg] About MTU?

From: Les Ginsberg <[email-masked]>
Date: Thu, 25 Apr 2002 08:35:17 -0700

The short answer is that you must configure the maximum LSP size that any
router in the area/domain will generate to be no larger than the smallest
MTU of any link in the area/domain that will be used for propagation - in
your example originatingLxLSPSize must be set to 997 (1000 - 3 bytes for
LLC1 header) on all routers.

The longer answer can be found at:

ftp://ftp.juniper.net/pub/isis/lspsize.PDF

This solution has been incorporated into the ISO 10589:2001 draft.

    Les

-----Original Message-----
From: Wang xuepu
To: [email-masked]
Sent: 4/27/02 5:44 AM
Subject: [Isis-wg] About  MTU?

Suppose there are three routers in the same area,and they are connected
by the ethernet.
such as:
 
 ___        ___         ___    
| A |______| B |_______| C | 
|___|e0  e0|___|e1   e0|___|
       
Suppose:
Router A: 
         the mtu of e0 is 1500.
Router B:
         the mtu of e0 is 1500.    
         the mtu of e1 is 1000.    
Router C:
         the mtu of e0 is 1000.    
Now:
When Router B receive a Router A's LSP from e0,the size of this LSP
should be 1500,the Router B should flood
the LSP,but B can not send this LSP throught e1.becase the mtu is too
small.
Is it correct?
if it is right,how can we solute this problem?
 
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