[c-nsp] RE: [cisco-bba] l2tp failover and loadbalancing

[Oliver Boehmer (oboehmer)]

Raj Panchal <mailto:raj.panchal at vsnl.co.in> wrote on Friday, January 27,
2006 7:40 AM:

> Dear Oliver,
> Thanks for the response.
> 
> In your example, you mentioned
> Tunnel-Preference = :1:"10",
> 
> What I understand is that this attribute will allow preference of
> tunnel and its attributes when multiple reply items are being sent as
grouped
> items to user as part of his access-requests
> 
> As per RFC the order of preference is higher for lower value of
> Tunnel- Preference, but I can see in your example value is constant
> "10" across all the 3 groups tagged with 1,2,3
> 
> So precisely will your configuration help me load balancing or
> failover for Tunnel-Server-Endpoint

Yes, setting the preference to the same value for multiple tagged groups
does load-sharing among this group, so it does what you want.

I have never tried it, but with a config like

       Tunnel-Medium-Type = :1:IP,
       Tunnel-Server-Endpoint = :1:"10.1.1.1",
       Tunnel-Preference = :1:"10",
       Tunnel-Type = :2:L2TP,
       Tunnel-Medium-Type = :2:IP,
       Tunnel-Server-Endpoint = :2:"10.1.1.2",
       Tunnel-Preference = :2:"10",
       Tunnel-Type = :3:L2TP,
       Tunnel-Medium-Type = :3:IP,
       Tunnel-Server-Endpoint = :3:"10.1.1.3",
       Tunnel-Preference = :3:"10",
       Tunnel-Type = :4:L2TP,
       Tunnel-Medium-Type = :4:IP,
       Tunnel-Server-Endpoint = :4:"10.1.1.4",
       Tunnel-Preference = :4:"20",
       Tunnel-Type = :5:L2TP,
       Tunnel-Medium-Type = :5:IP,
       Tunnel-Server-Endpoint = :5:"10.1.1.5",
       Tunnel-Preference = :5:"20",
       Tunnel-Type = :6:L2TP,
       Tunnel-Medium-Type = :6:IP,
       Tunnel-Server-Endpoint = :6:"10.1.1.6",
       Tunnel-Preference = :6:"20"

we would load-share across 10.1.1.1, .2 and .3 (all pref=10), and
fail-over and load-share across .4, .5 and .6 (all pref=20) once all the
first three endpoints are unavailable..

	oli