[c-nsp] cbgpPeer2AdvertisedPrefixes different than 'show bgp nei X advertised-routes'

[David Hubbard]

I’m curious if anyone has noticed issues with CISCO-BGP4-MIB values related to prefix counts on IOS XR?  I’m querying a 6.2.3 device and seeing weird results.

I’d like to monitor the number of prefixes advertised and received from eBGP peers.  The mib defines cbgpPeerAcceptedPrefixes as a Counter32, and cbgpPeerAdvertisedPrefixes as a Gauge32.  That’s the first thing that doesn’t make sense.  Both values should be Gauge32 since counting ongoing changes to the prefix counts is a useless metric for the device to be tracking.

So, first is accepted prefixes; cbgpPeerAcceptedPrefixes.  Even though it’s defined in the MIB as a Counter32, the data being returned appears to be a current reading, i.e. a Gauge32.  I can make do with the wrong data classification since the values seem to be what I want regardless.

Then I’ve got cbgpPeerAdvertisedPrefixes, which is defined as a Gauge32, but appears to be behaving like a counter, making the data completely useless.  One peer is showing double the advertisements of another, even though the actual advertisements are the same.  That particular peer has flapped once since the monitoring began, hence my suspicion that it’s behaving like a counter.  The value returned for iBGP peers, on my edge routers, is incrementing constantly, currently at 37 million+, adding to the evidence it’s a counter, and useless.  I have not yet found an OID I can query that gives me a current advertised count.

Do other platforms behave like this or would this be a bug in the implementation on my particular device?

Thanks