Dear experts, a customer of mine has the following OSPF scenario: ......................................................... . . . area0 area10 totally stub . . | | . . | +----+ DR | . . |---|RT1|--------| . . | +---+ | . . | | . . | +----+ | . . |----|RT2|------| . . | +----+ | +------------+ . . | |----|host5/6/7| . . | +---+ | +------------+ . . DR |-----|RT3|-----| . . | +---+ | . . | | . . | +---+ | . .BDR |------|RT4|----| . . | +---+ BDR . . | . . . ...........................................................
Four MX routers RT1, RT2, RT3 and RT4 running OSPF as ABR (area 0 and area 10 totally stub), on area 10 there are some host talking OSPF (host5/6/7 in reality are more). On MX side I see a lot of OSPF retransmissions on area 0 expecially on the DR-other (RT1 and RT2), I guess it’s due to the following: 1- Host 5 or other send LSA update to all routers on area 10 (RT1, RT2, RT3, RT4) 2- All routers advertise the update to all the others routers in the same Ethernet segment 3- If for example RT1 and RT2 simultaneously send the same update towards RT3, RT3 will send the ACK only the first it gets (let’s say from RT1) 4- So RT2 will wait for ACK, put LSA in the Link State Retransmit List and after 5 seconds (default LSA retransmit interval), RT2 retransmit to RT3 5- After retransmission RT2 get the ACK from RT3 Am I wrong ? Does it sounds as reality ? Should I expect instability, which the customer did not get till now ? Cheers James _______________________________________________ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp