From: darbyweaver@yahoo.com
Date: Mon May 22 2006 - 08:51:35 ART
DR election between two devices.
Seems simple enough...
First look at the basics and the criteria for selecting a DR.
I think there are a few ways to do this.
1. ip ospf priority 0 on the spokes is nice
2. ip ospf priority 255 on the hub if it always had to win (but wait)
3. Highest router-id also wins a DR election, so we can either specify it manually using router-id 255.255.255.255 (a 32-bit number) or we can create a loopback with the highest IP address.
Here are some useful links:
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a0080094054.shtml
http://www.cisco.com/warp/public/104/2.html#10.1
DR Election
DR and BDR election is done via the Hello protocol. Hello packets are exchanged via IP multicast packets (Appendix B) on each segment. The router with the highest OSPF priority on a segment will become the DR for that segment. The same process is repeated for the BDR. In case of a tie, the router with the highest RID will win. The default for the interface OSPF priority is one. Remember that the DR and BDR concepts are per multiaccess segment. Setting the ospf priority on an interface is done using the ip ospf priority <value> interface command.
A priority value of zero indicates an interface which is not to be elected as DR or BDR.
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f0e.shtml
Commands that can be helpful:
debug ip ospf adjacency
show ip ospf neighbor
show ip ospf database
show ip ospf interface S0/0
This archive was generated by hypermail 2.1.4 : Thu Jun 01 2006 - 06:33:22 ART