Host Routes For Load Balancing - Lenovo RackSwitch G8264 Application Manual

3. Assign MD5 key ID to OSPF interfaces on switches 1, 2, and 3.
4. Enable OSPF MD5 authentication for Area 2 on switch 4.
5. Configure MD5 key for the virtual link between Area 2 and Area 0 on switches 2
and 4.
6. Assign MD5 key ID to OSPF virtual link on switches 2 and 4.

Host Routes for Load Balancing

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RS G8264(config)# interface ip 1
RS G8264(config­ip­if)# ip ospf message­digest­key 1
RS G8264(config­ip­if)# exit
RS G8264(config)# interface ip 2
RS G8264(config­ip­if)# ip ospf message­digest­key 1
RS G8264(config­ip­if)# exit
RS G8264(config)# interface ip 3
RS G8264(config­ip­if)# ip ospf message­digest­key 1
RS G8264(config­ip­if)# exit
RS G8264(config)# router ospf
RS G8264(config­router­ospf)# area 1 authentication­type md5
RS G8264(config­router­ospf)# message­digest­key 2 md5­key test
RS G8264(config­router­ospf)# area­virtual­link 1 message­digest­key 2
RS G8264(config­router­ospf)# exit
ENOS implementation of OSPF includes host routes. Host routes are used for
advertising network device IP addresses to external networks, accomplishing the
following goals:
 ABR Load Sharing
As a form of load balancing, host routes can be used for dividing OSPF traffic
among multiple ABRs. To accomplish this, each switch provides identical services
but advertises a host route for a different IP address to the external network. If
each IP address serves a different and equal portion of the external world,
incoming traffic from the upstream router must be split evenly among ABRs.
 ABR Failover
Complementing ABR load sharing, identical host routes can be configured on
each ABR. These host routes can be given different costs so that a different ABR
is selected as the preferred route for each server and the others are available as
backups for failover purposes.
 Equal Cost Multipath (ECMP)
With equal cost multipath, a router potentially has several available next hops
towards any given destination. ECMP allows separate routes to be calculated for
each IP Type of Service. All paths of equal cost to a given destination are calcu‐
lated, and the next hops for all equal‐cost paths are inserted into the routing table.
Chapter 35: Open Shortest Path First
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