Which statement describes Cisco PfR link groups?
A.
Link groups enable Cisco PfR Fast Reroute when NetFlow is enabled on the external interfaces of
the border routers.
B.
Link groups define a strict or loose hop-by-hop path preference.
C.
Link groups are required only when Cisco PfR is configured to load-balance all traffic.
D.
Link groups are enabled automatically when Cisco PfR is in Fast Reroute mode.
E.
Link groups set a preference for primary and fallback (backup) external exit interfaces.
The Performance Routing – Link Groups feature introduced the ability to define a group of exit links
as a preferred set of links, or a fallback set of links for PfR to use when optimizing traffic classes
specified in an PfR policy. PfR currently selects the best link for a traffic class based on the
preferences specified in a policy and the traffic class performance—using parameters such as
reachability, delay, loss, jitter or MOS—on a path out of the specified link.
Reference.
http://www.cisco.com/c/en/us/td/docs/ios/pfr/configuration/guide/15_1/pfr_15_1_book/pfr-linkgroup.
html