9.1 Examining the Routing Table  
  9.1.9 Observing multiple paths to destination  
Some routing protocols support multiple paths to the same destination. Unlike single path algorithms, these multi-path algorithms permit traffic over multiple lines, provide better throughput, and are more reliable.

Rt1 has two routes to network 192.168.30.0. The variance command will be set on Rt1 to ensure that both paths to network 192.168.30.0 are utilized.

Figure shows the output from show ip route from Rt1 before the variance is configured. Serial 0/0 is the only route to 192.168.30.0.

Figure shows the output from show ip route from Rt1 after the variance is configured.

The preferred route is interface FastEthernet 0/0, but Serial 0/0 will also be used. To verify load balancing, ping 192.168.30.1.

After the ping is executed the preferred route is using interface Serial 0/0. IGRP will use load balancing between the two links.

 

Web Links

Using the Extended ping and Extended traceroute Commands

http://www.cisco.com/en/US/tech/ tk826/tk365/ technologies_ tech_ note09186a0080093f22.shtml