have a quick querey about BGP med. I thought that med was always set to 0 unless changed by a route map . I have been running a ospf topology with 2 seperate bgp edge routers connecting to one singular bgp speaker router and the med is being set automatically.
How is this value set and what makes up the calculation.
i have done some testing and i have found bandwidth of a link in the path affects it but would like to know how its making this descision.
If you originate the prefix via redistribution or with the network command, the IGP meric will be copied to the BGP MED value when advertising to eBGP peers. If you originate the prefix with the aggregate-address command, the MED value is not copied. That's my understanding.
thanks for the reply.
so how does bgp make the translation from say ospf or eigrp to the bgp metric value and can this be manipulated.
Do you know of any reading on this
I just labbed this. And sure enought. When doing an aggregate the MED isn't copied to the aggregate. You can however use an attribute-map with the aggregate command to set a metric.