when there is PE and CE router. On CE router RIP is running and on PE router when we tried to redistribute the routes from BGP to RIP we need to use below command to preserve the RIP metrics.
“redistribute bgp <asn> metric transparent”
When RIP routes are redistributed into BGP, the route metric is stored in the BGP MED value. When BGP routes are redistributed into RIP, and the transparent keyword used, the MED value is copied back as the RIP metric. Without the transparent keyword, the metric value specified is applied to all the routes.
for the technical implementation with “metric transparent” already mentioned make sure your BGP med value is not larger than 15 in any case. Otherwise the RIP metric will assume the route to be unreachable and not announce it from PE to CE.
One way of having larger MED values is to use OSPF or EIGRP on another site, which metric will be copied to BGP MED during redistribution.
If only RIP is used with only single homed sites then this should work properly.