iBGP Scaling

Truman Boyes truman at suspicious.org
Mon Mar 30 07:19:33 CDT 2009


Hi there,

Interesting post. Couple things you touched on; firstly is your IGP  
having a scaling issue? I have seen networks with > 500 routers in  
area 0.0.0.0, however the LSDB was limited to links and loopbacks.  
Using route reflectors may help to some degree on memory, in that only  
the best route will be reflected to clients. If you are looking to do  
some things like MPLS IPVPNS or other TE stuff, you might want to  
stick with one AS / one IGP. It just makes things easier.

If your routers can support MPLS VPNs, you may be able to leverage  
route target filtering on each PE device. If you are just memory  
starved and plan to continue with a standard Internet routing domain,  
I would look at tagging all routes on ingress and figuring out which  
routes can be summarized or filtered out on the border / aggregation  
routers.

Kind regards,
Truman


On 29/03/2009, at 4:13 AM, tt tt wrote:

>
> Hi List,
>
> We are looking to move our non infrastructure routes into iBGP to  
> help with our IGP scalability (OSPF).  We already run full BGP  
> tables on our core where we connect to multiple upstream and  
> downstream customers.  Most of our aggregation and edge routers  
> cannot hold full tables and it's certainly not possible to upgrade  
> them. Is there any reason why we shouldn't filter iBGP routes  
> between our core and aggregation layers (we plan to use route  
> reflectors) or should we be look at using a private AS number per POP?
>
> Thanks
>
> Dave
>
>
>
>
>





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