[Babel-users] Babel and multipath [was: atomic updates ...]

[Leen Besselink]

On Mon, May 06, 2013 at 12:18:26AM +0200, Juliusz Chroboczek wrote:
> > Which means a machine is connected to multiple different L2-domains
> > and automatically finds other machines connected to those L2-domains.
> [...]
> > My plan was to define filters to prevent it from announcing other routes.
> 
> The following in /etc/babeld.conf:
> 
>   out my.ip.addr.ess/32 allow
>   out deny
> 
> should do the trick.
> 

Yes, that was my plan.

> Why do you need ECMP?
> 
> -- Juliusz

My use case is the datacenter.

I've seen to many failures of protocols, implementations and hardware to
know I want to try something different and simpler for the datacenter with
quick convergence. I want to run a routing protocol on the server and create
redundany that way. No fancy tricks, like running routing protocols like IS-IS
or OSPF on switches or even BGP (judging by some talks I've seen Microsoft seem
to do that). And no LACP connected to the same switch or stacks. Things like Linux
bonding are also a hack and also fail in a number of different situations.
And not all switches handle it the same way.

Here is a picture:

       --[server1]--
       |           |
   [switch1]   [switch2]
       |           |
       --[server2]--

This can scale up to a few switches, maybe up to a hundred servers on the same L2 domain.

When (part of or a whole) L2 domain fails, the servers can see they can only reach the
other servers on the other L2 domain. I want the server to autonomously decide what to do.

Babel would use the IPv6 link-local address to announce it presence and a IPv6-address would
be attached to the local loopback.

IPv6 is enough to run an internal network.

You'd need to connect a (probably multiple OSPF) router to get outside of the L2-domain.

The implementation of Babel in Quagga-RE has support for authentication and Quagga also
supports OSPF.