MPLS Fundamentals

Load Balancing

The paths london-rome-sydney and london-madrid-sydney are made equal cost. When you are sending traffic with the same source and same destination IP address from new-york to sydney, all traffic takes the same path. At router london, all this traffic is forwarded out onto only one of the two possible paths. That is because of the load-balancing treatment of labeled packets in Cisco IOS. The default behavior in Cisco IOS is to look at the IP header underneath the label stack and use the same hashing algorithm as CEF to determine the load balancing. Because the default is CEF per destination load balancing, all traffic that has the same pair of source and destination IP address is switched out of the LSR onto the same path. With ...