
Configuring IP Services
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303528-A Rev 00
Enabling Equal-Cost Multipath Support
By default, IP stores the best next hop to a destination in the routing table. If
traffic arrives on an interface, IP determines the best route to the destination and
forwards all packets out the next-hop interface.
IP equal-cost multipath support (ECMP) is a load-balancing feature that allows IP
to distribute traffic over multiple (up to five) equal-cost paths to the same
destination.
IP supports three methods of distribution for equal-cost routes:
• Round-robin distribution. IP forwards each packet to a different next hop until
it reaches the end of the list of available next hops; then it repeats the list.
Round-robin distribution makes full use of available resources but may cause
packets to be delivered out of order.
• Source-destination hash distribution based on the source and destination
address. IP forwards all packets with a given source and destination address to
the same next hop. This method increases the chances that the packets will be
delivered in order.
• Destination-hash distribution based on the destination address only. IP
forwards all packets with a given destination address to the same next hop.
By default, equal-cost multipath support is disabled on the router. You can use the
BCC or Site Manager to enable the feature and choose a distribution method.
Using the BCC
Navigate to the IP global prompt and enter:
ecmp-method
method
method is one of the following:
disabled
(default)
roundRobin
srcDestHash
destinationHash
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