FTOS Configuration Guide for the C-Series - Force10 Networks

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 Force 10 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 Force10 router to
match the Cisco configuration. Use the command “ip ospf dead-interval ” in interface mode:
Figure 380 Command Example: ip ospf intervals
Force10(conf)#int gi 2/2
Force10(conf-if-gi-2/2)#ip ospf hello-interval 20
Force10(conf-if-gi-2/2)#ip ospf dead-interval 80
Force10(conf-if-gi-2/2)#
Figure 381 OSPF Configuration with intervals set
Force10 (conf-if-gi-2/2)#ip ospf dead-interval 20
Force10 (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)
Force10 (conf-if-gi-2/2)#
For more information regarding this unctionality or for assistance, go to www.force10networks.com/
support.
Configuration Information
Dead Interval
Set at 4x
Hello Intral
Dead Interval
Set at 4x
Hello Interval
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.
FTOS Configuration Guide, version 7.7.1.0 539