Dell Force10 S4820T S4820T Configuration Guide - Page 697

OSPF ACK Packing The OSPF ACK Packing feature bundles multiple LS acknowledgements in a single packet, significantly reducing the number of ACK packets transmitted when the number of LSAs increases. This feature also enhances network utilization and reduces the number of small ACK packets sent to a neighboring router. OSPF ACK packing is enabled by default, and non-configurable. OSPF Adjacency with Cisco Routers To establish an OSPF adjacency between Dell Force10 and Cisco routers, the hello interval and dead interval must be the same on both routers. In FTOS the OSPF dead interval value is, by default, set to 40 seconds, and is independent of the OSPF hello interval. Configuring a hello interval does not change the dead interval in FTOS. In contrast, the OSPF dead interval on a Cisco router is, by default, four times as long as the hello interval. Changing the hello interval on the Cisco router automatically changes the dead interval as well. To ensure equal intervals between the routers, manually set the dead interval of the Dell Force10 router to match the Cisco configuration. Use the command "ip ospf dead-interval " in interface mode: Figure 33-6. Command Example: ip ospf intervals FTOS(conf)#int gi 2/2 FTOS(conf-if-gi-2/2)#ip ospf hello-interval 20 FTOS(conf-if-gi-2/2)#ip ospf dead-interval 80 FTOS(conf-if-gi-2/2)# Dead Interval Set at 4x Hello Interval Figure 33-7. OSPF Configuration with intervals set FTOS (conf-if-gi-2/2)#ip ospf dead-interval 20 FTOS (conf-if-gi-2/2)#do show ip os int gi1/3 GigabitEthernet 2/2 is up, line protocol is up Internet Address 20.0.0.1/24, Area 0 Process ID 10, Router ID 1.1.1.2, Network Type BROADCAST, Cost: 1 Transmit Delay is 1 sec, State DR, Priority 1 Designated Router (ID) 1.1.1.2, Interface address 30.0.0.1 Backup Designated Router (ID) 1.1.1.1, Interface address 30.0.0.2 Timer intervals configured, Hello 20, Dead 80, Wait 20, Retransmit 5 Hello due in 00:00:04 Neighbor Count is 1, Adjacent neighbor count is 1 Adjacent with neighbor 1.1.1.1 (Backup Designated Router) FTOS (conf-if-gi-2/2)# Dead Interval Set at 4x Hello Interval For more information regarding this functionality or for assistance, go to www.force10networks.com/ support. Configuration Information The interfaces must be in Layer-3 mode (assigned an IP address) and enabled so that they can send and receive traffic. The OSPF process must know about these interfaces. To make the OSPF process aware of these interfaces, they must be assigned to OSPF areas. Open Shortest Path First (OSPFv2) | 697