paul.matthews Tue, 02/03/2009 - 07:39
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I am sorry, your question is not clear, so I'll thow a bit of the standard info at you to see any helps.


First metrics - the route selection within BGP is complex, and uses a number of metrics, some are of local significance only, some are next hop only, so there is no "clear" metric to select.


In terms of selecting a route from BGP ahead of a similar route from an IGP, The Administrative distance is important. eBGP uses an AD of 20 which beats IGPs ast standard. iBGP uses 200, which is beaten by IGPs.


so if a route is learned from eBGP, that will normally be the preferred route.


I hope I have given you some help, even if only to formulate your question better.

Giuseppe Larosa Tue, 02/03/2009 - 08:23
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Hello Paul,

question is not very clear


however when you redistribute an IGP into BGP the BGP MED can be a copy of IGP metric.


see

http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_bgp4.html#wp1014369


set metric-type internal


in route-map used to redistribute IGP into BGP this command can be used


this allows to have multiple routers and to build a hierarchy of BGP routes.


Hope to help

Giuseppe



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