Network Router User Manual

Chapter 12: BGP Configuration Guide
152 SmartSwitch Router User Reference Manual
Notes on Using Communities
When originating BGP communities, the set of communities that is actually sent is the
union of the communities received with the route (if any), those specified in group policy
(if any), and those specified in export policy (if any).
When receiving BGP communities, the update is only matched if all communities
specified in the optional-attributes-list option of the ip-router policy create command are
present in the BGP update. (If additional communities are also present in the update, it
will still be matched.)
Local Preference Examples
There are two methods of specifying the local preference with the bgp set peer-group
command:
• Setting the local-pref option. This option can only be used for the internal, routing, and
IGP group types and is not designed to be sent outside of the AS.
• Setting the set-pref option, which allows GateD to set the local preference to reflect
GateD’s own internal preference for the route, as given by the global protocol
preference value. Note that in this case, local preference is a function of the GateD
preference and set-pref options.
Figure 14 shows a BGP configuration that uses the BGP local preference attribute in a
sample BGP configuration with two autonomous systems. All traffic exits Autonomous
System 64901 through the link between router SSR13 and router SSR11. This is
accomplished by configuring a higher local preference on router SSR13 than on router