Amit,

The following links explain it better.

http://discuss.microsoft.com/SCRIPTS/WA-MSD.EXE?A2=ind0008&L=OSPF&P=R2394

http://discuss.microsoft.com/SCRIPTS/WA-MSD.EXE?A2=ind0008&L=OSPF&P=R2279

-Vishwas

-----Original Message-----
From: Manral, Vishwas [mailto:VishwasMNETPLANE.COM]
Sent: Friday, January 25, 2002 10:37 PM
To: OSPFDISCUSS.MICROSOFT.COM
Subject: Re: Database Describtion Fragmentation!!

Amit,

From RFC2328
        If the Interface MTU field in the Database Description packet
        indicates an IP datagram size that is larger than the router can
        accept on the receiving interface without fragmentation, the
        Database Description packet is rejected.

This is probably because OSPF has no method of fragmentation and relies on
IP for fragmentation. In case a an LSU is sent which is bigger than MTU, it
can be dropped, causing problems in the routing table. This is why I think,
DB description packets are used to convey Interface MTU(and are dropped in
case of a mismatch). Mind you, Interface MTU over virtual links is set to be
0.

Maybe John/Alex will explain it better.

Thanks,
Vishwas

-----Original Message-----
From: Amit Srivastava [mailto:amit_ospfYAHOO.COM]
Sent: Thursday, January 24, 2002 2:43 PM
To: OSPFDISCUSS.MICROSOFT.COM
Subject: Database Describtion Fragmentation!!

Hi All,
      Why is that the database describtion packets if
received after fragmentation is discarded!!
regards
Amit

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