[c-nsp] downlink bgp interconnect best practices

[Gert Doering]

Hi,

On Tue, May 31, 2011 at 02:21:05PM +0400, Nikolay Shopik wrote:
> I would like to hear what are best practices when interconnecting 
> downlinks. We are small transit ISP, right now we are in middle of 
> network upgrade, and I would like to make network more redundant so it 
> less affect our downlinks when we having planed/unplanned maintenance.
> 
> Right now we have two borders 7201 and 7206 with 3 uplinks and 2 local 
> IX. And we terminate BGP session for downlinks at one of border, no bgp 
> multihop, all downlinks receive bgp full-view.

We try to separate "core + uplink" and "customer connection" routers,
so we can do works on core routers witout affecting customers - and
vice versa, if we have to reboot a "customer connection" router, we
know which customers are affected and that nothing else is.

So a "text book" scenario would have two "core/uplink" routers here,
fully meshed with two "customer access" boxes (so there's no single
switch in between that could break), and customers are then connected
to one or both of the "access" routers.

uplink/IX  uplink/IX
    |        |
    CR1 -- CR2
     | \  / |
     |  \/  |
     |  /\  |
     | /  \ |
    AR1    AR2
     |      |
     customers
   

Now, reality doesn't always work like this for smaller shops - if the
customer connects with a bigger pipe than what we have to the access
routers (like "2 Gbit ether channel uplink"), they get connected to 
the "core" box - because it's sometimes not very economic to roll out
10Gig everywhere, just for a single 2G customer...

gert
-- 
USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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