Re: [OSPF] LSA Data Base Exchange Between the Master and the Slave

Hi Acee,

I would like to thank you for finding time to reply my mail.

I had gone through section 10.6 and 10.8 still i would like to know in
section 10.6 what these below line means.

*            The slave must send a Database Description Packet in reply.
            If the received packet has the more bit (M) set to 0, and
            the packet to be sent by the slave will also have the M-bit
            **set to 0, the neighbor event ExchangeDone is generated.*

 *Best Regards,*

*Biswajit Sadhu*

On Wed, Jul 3, 2013 at 7:00 PM, Acee Lindem <acee.lindem@ericsson.com>wrote:

>  Hi Biswajit,
>
>  On Jul 3, 2013, at 6:35 AM, Biswajit Sadhu wrote:
>
>  Hi All,
>
>  I have a query in the OSPF Design of LSA Data Base Exchange.
>
>  In data base exchange process if the master has smaller database the the
> slave and the master sends the More bit as zero in its DB packet  then the
> slave should also set the M bit to 0 in reply to the master's DB packet
> with the same sequence number ?
>
>
>  No. The slave should continue to set the M bit until it has sent its
> entire database. The master should continue to poll the slave with
> increasing sequence numbers until the slave has completed exchanging its
> entire database and cleared the M bit. Excerpt from RFC 2328:
>
>         This sending and receiving of Database Description packets is
>         called the "Database Exchange Process".  During this process,
>         the two routers form a master/slave relationship.  Each Database
>         Description Packet has a sequence number.  Database Description
>         Packets sent by the master (polls) are acknowledged by the slave
>         through echoing of the sequence number.  Both polls and their
>         responses contain summaries of link state data.  The master is
>         the only one allowed to retransmit Database Description Packets.
>         It does so only at fixed intervals, the length of which is the
>         configured per-interface constant RxmtInterval.
>
> Each Database Description contains an indication that there are
> more packets to follow --- the M-bit. The Database Exchange
> Process is over when a router has received and sent Database
> Description Packets with the M-bit off.
>
> Read RFC 2328 sections 10.6 and 10.8 and it should be clear. The actions of the database exchange master and slave are described in detail.
>
>
>  Hope this Helps,
> Acee
>
>
>
>
>
>
>
>
>   Should the data base exchange stop after that. what if the slave had
> more lsa's to send to the Master?
>
>  What about the vice-versa case where Master has a large Data base to
> exchange then the Slave  ?
>
>     As per page 101 .rfc 2328 i am quoting few lines for the same RFC
>
>      http://tools.ietf.org/html/rfc2328
>
>
>       *   Master
>             Increments the DD sequence number in the neighbor data
>             structure.  If the router has already sent its entire
>             sequence of Database Description Packets, and the just
>             accepted packet has the more bit (M) set to 0, the neighbor
>             event ExchangeDone is generated.  Otherwise, it should send
>             a new Database Description to the slave.
>
>         Slave
>             Sets the DD sequence number in the neighbor data structure
>             to the DD sequence number appearing in the received packet.
>             The slave must send a Database Description Packet in reply.
>             If the received packet has the more bit (M) set to 0, and
>             the packet to be sent by the slave will also have the M-bit
>             **set to 0, the neighbor event ExchangeDone is generated.**
>             Note that the slave always generates this event before the
>             maste**r.*
>
> *
> *
>
>  *Best Regards,*
>
> *Biswajit Sadhu*
>  _______________________________________________
> OSPF mailing list
> OSPF@ietf.org
> https://www.ietf.org/mailman/listinfo/ospf
>
>
>