Interval of Database description packet in OSPF

[thangaRasu]

what is the interval for sending database description packet

My assumption is if LSRefresh is expired means it will start to send database description packets after that LSR, LSU then LSA

Thanks in advance

[antonio.guirado]

Hello again,

to refresh the LSA only LSUpdates an LS ACK are used. BDB packet is only to check if some fields have changed. When a router have to refresh an LSA, it sends directly a LS Update packet.

Regards.

[thangaRasu]

Thank you i am clear about all packet types but not clear in the use of database description packet can you please explain

it.

[Juan Urti]

Hi, when the router start the neighbor proccess, it exchange the DBD, that includes a list of neighbors and a summary of the routes.

If the other router need more information about some of this routes (because it doesn´t know), the router will send a LS Request.

After that, and the LS ack, the neighboring will be FULL.

Also, every 30 minutes by default, the routers send the COMPLETE database to all neighbors, to check the consistency.

Good Bye.

Juan

[antonio.guirado]

Hello,

DBD packets transport LSA headers that includes only some fields describing the LSA: LS Age, LS Checksum, LS ID.

When a OSPF adjacency is established the peers exchange LSA headers using DBD packets. If some LSA is not

known by a peer or is more recent, the router A send a LSRequest to the peer B to receive the full LSA. The peer B send

the full LSA in a LS Update packet. Then, the router A sends a LS Ack.

Regards.