Showing posts from January, 2014

OSPF over Frame-Relay, focus on Network Types

Don't forget that in Frame-Relay "broadcast" is defined ONLY DIRECTLY HUB AND A SPOKE, ON BOTH SIDES of the pvc!!! What this does is tell the routers “Hey if you have any broadcast messages, go ahead and send them down this DLCI as a unicast” So basically it is a way to send broadcast messages on a non-broadcast medium. Don't include "broadcast" between the SPOKEs, as the Hellos won't be able to traverse the HUB.
Type 1: NON-BROADCAST- use "neighbor" command on HUB to use UNICAST for OSPF OSPF uses Multicast, which Router considers to be a kind of Broadcast. Due to the non-broadcast nature of Frame-Relay it can be assumed that this is the DEFULT OSPF network type over FR. - Set the OSPF Priority to 0 on all the SPOKEs, so HUB is elected as the DR, and SPOKEs neither DR nor BDR - Non-broadcast network type in OSPF uses “slow” timers meaning 30 second hello and 120 second dead-time. Here it will not affect us, as all neighbor types match.
Type 2: BRO…