Routing issues

Ondrej Zajicek santiago at crfreenet.org
Wed Dec 7 10:51:20 CET 2011


On Tue, Dec 06, 2011 at 10:06:30AM -0500, dspazman at epicup.com wrote:
> I tried modifying the example.  Here is the situation.

> No clients, just have my own block of IPs I want to announce
> (A.A.A.A/22).  I also have two /29s, one from each provider (Y.Y.Y.A/29,
> Y.Y.Y.B/29) that contains the external IP address for each of my
> router's two ethernet interfaces, as assigned by each ISP.  The two
> providers I'm trying to just run so one is preferred, but both can be
> used.  The asymetric isn't a huge deal, so if it's simpler to take it
> out, that's ok also.

In that case i would suggest to forget multiple routing table and keep it simple, like in:

https://git.nic.cz/redmine/projects/bird/wiki/BGP_example_2

(or the later filtering example)

(and just insert several your ASNs to AS path in export filter to less preferred uplink)

> Also, besides the bird setup, I ran the following rules:
> ip rule add iif eth2 table 1
> ip rule add iif eth5 table 2

> (This is on Ubuntu, btw, and my two ISP interfaces are eth2 (my less prefered one) and eth5 (my high speed 10 Gig fiber one).

I thought you want to using multiple routing tables to route your traffic from your two internal links.
There is no reason to route differently traffic received from each uplink.

> The problems / questions I ran into was this.
> 
> 1) Does the table 1 / table 2 need to be declared in the underlying system first?  I didn't think so, like in /etc/iproute2/rt_tables?  Because the IP rules seemed to work for pinging out on the interface.

No

> 3) Is the ospf part needed or helpful?

If you use OSPF in your network, then yes, otherwise no.
But your OSPF config seems to be completely pointless.
I would suggest to read some general texts about OSPF, BGP and routing.

> Is it a good practice to have the BGP router also run OSPF, in general?

I think it is, unless in trivial cases. But in most cases you do not
have OSPF session with your provider.

-- 
Elen sila lumenn' omentielvo

Ondrej 'SanTiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."
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