Cabletron Systems 9032578-05 manual Local Preference Examples

Chapter 12: BGP Configuration Guide

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-listoption 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-groupcommand:

•Setting the local-prefoption. 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-prefoption, 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

152 SmartSwitch Router User Reference Manual