Re: DB Synchronization

[Parag Deshpande <[e-mail]>]

I ran a small program with the following values -

In this case the checksums are always the same! because
m1 & m2 are multiple of 8.
m1= 16 m2 = 24. ( also 8, 32)

CK_SUM({00, 00, 00, FF}, 4) = CK_SUM( {00,00,FF,FF}, 4)
= CK_SUM( {00,FF,FF,FF},  4) = CK_SUM( {FF,FF,FF,FF}, 4)
= 0xFFFF

(It does not matter what N1 is)

Or I am goofing up somewhere :-)

Parag

----- Original Message -----
From: Rikki Nguyen <[e-mail]>
To: <[e-mail]>
Sent: Friday, August 29, 2003 12:53 PM
Subject: Re: DB Synchronization


> Parag Deshpande wrote:
> > Hi,
> >
> > I had a doubt ->
> >
> > 2 routers A and B have an ospf adjacency.
> >
> > Router A sends an ASExt lsa for network N1/m1 with LSID = N1.
> > Then Router A goes down & comes up again & reoriginates
> > ASExt lsa for network N1/m2 with LSID = N1 and then
> > gets adjacent with Router B.
> >
> > **where m1 != m2 & they are multiple of 8. (/8, /16..)
> > also assuming that all other parameters are same.
> >
> > However in this case the DB Exchange will fail to
> > synchronize these LSAs bcoz they appear
> > to be similar- LSID, SeqNum, Checksums being equal**
> > and thus will have to wait for the LSA to get refreshed.
>
> The checksum is computed over the entire LSA body,
> this includes the netmask.  Since the netmasks are
> different, it would be difficult for the checksum
> to be the same.
>
> >
> > I was wondering whether this can be resolved faster.
> >
> > Thanks
> > Parag
> >
>