It means that if the slave receives a database exchange packet indicating the
master has sent everything and the slave has also sent everything to the master
(or will have with the database exchange packet to be sent), the database
exchange is complete.
Thanks,
Acee
On Jul 3, 2013, at 11:31 AM, Biswajit Sadhu wrote:
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
<[email protected]<mailto:[email protected]>> 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
master.
Best Regards,
Biswajit Sadhu
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