ISR4331 BGP Network Peaked

[ilhambasuki]

Hi,

I found issue on ISR4331 running BGP. When I checked bgp summary, it shows that network peaked happened at specific time. I attached the screenshot.

I know perhaps it's not recommended, but this ISR4331 is running as BGP route-reflector with 40-50 peers. The problem is some peers able to establish BGP peering but stuck with SE (route refresh) flag and then BGP down with notification of hold timer expired.

I assume this router cannot handle more than 12k networks from its peers, so I try to remove some established/normal peer. But no new peer established to this router. Those previous peers I mentioned before, still flap with same reason.

So, I'd like to ask if anyone has experience with ISR4331 as BGP route-reflector? I found document that rule of thumb is 1GB of RAM for 750k prefixes, and that number is still far away on my router's BGP prefixes.

Thanks before.

[ilhambasuki]

Sorry, the attachment is missing before.

 

 

[balaji.bandi]

What is the version of the IOS code running,  and what is the memory size of the device?

check some requirement :

https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/12512-41.html

[ilhambasuki]

Hi,

IOS version is 17.12.04 and memory size is 4GB (default of ISR4331)

[balaji.bandi]

As far as I know, 4GB should be good, but is it impacting any performance? Or is this just a query?

If you are still concerned, a new version code will be released, 17.12.5, in a week or two, so upgrade and check again.

[ilhambasuki]

This is impacting some peer neighborship flap every 3 minutes when hold timer expired. 

[Giuseppe Larosa]

Hello @ilhambasuki ,

for a BGP route reflector memory is not the only parameter .

A fast enough CPU is needed and in the past I remember also suggestions on tuning the buffers on data interfaces.

>> but this ISR4331 is running as BGP route-reflector with 40-50 peers

It depends on how many upgrade groups if all peers share the same outbound policy all of them are in the same update group and the router will prepare the update and it will send it to all of them after adding the BGP originator ID and BGP cluster ID. if there are differentiated outgoing policies the RR work is much harder.

Generally I have seen ASR 1000 used as BGP RRs in enterprise or ISP networks.

There can also be an interoperability issue for some feature like route refresh .

you may need to remove features that are not interoperable.

Hope to help

Giuseppe

[ilhambasuki]

Hi @Giuseppe Larosa ,

Thanks for you insight. How about ASR 902? I know it's primary purpose is not as BGP RR, but will it have better BGP performance than ISR4331?

Hi @balaji.bandi ,

I haven't try upgrade it to 17.12.5. Now I consider using other type of router.

[Giuseppe Larosa]

Hello @ilhambasuki ,

ASR 902 is more comparable to a ME 3400 or ME 3800 it is a device specialized for PE role in metro ethernet . ASR 902 CPU ( there are two of three generations of Route Processors) is for sure weak when compared to an ASR 1000.

However , the ASR 902 CPU should be better then one of the ISR4331 so if you have one available you can give it a try but it is not a recommended platform for the role of BGP RR server.

Hope to help

Giuseppe

[balaji.bandi]

Sure what ever works for you.

[kirank10]

hi @ilhambasuki  The ISR4331 is a branch router and not optimized for large-scale BGP route-reflection.
Consider using a higher-end ISR, ASR, or CSR1000v for route-reflection.

[balaji.bandi]

May be try uplift the model of the device which support or suggest to Open a TAC case (if you not able upgrade the hardware)

Have you tried upgrading the IOS XE latest code ?