Specifying Preference to a Path-Group


router path-selection
load-balance policy <name>
path-group <group-name> [ priority <number>]
path-group <group-name> 

Preference can be specified for path-groups. Flows are load balanced based on path group priority. The lower the number the higher the priority is given to the path group. If not specified, default policy is 1 (highest). If multiple path groups in the same load-balance profile have same priority traffic will be load balanced among them. If no paths in a path-group are available then paths from the next lower priority is considered. Paths may not be available because of the following reasons:

  1. Interface is down
  2. Route is not resolved
  3. Path keepalives have failed
  4. Specified constraints for the load balancing policy is not met


For example, configuring load balancing for voice traffic with MPLS path preference and Internet as backup.

switch(config-dynamic-path-selection)#load-balance policy voice
switch(config-load-balance-policy-voice)#path-group mpls
switch(config-load-balance-policy-voice)#path-group internet

When MPLS path is down then all the existing flows are forwarded through Internet paths. When MPLS path is up again, all the new flows are forwarded through MPLS paths.