Hi all,
first post for me here...

I tried to search on the topics but didn't find anything to solve my problem.
I have an x86 used as PPPoE concentrator and would like to install another server to use as backup. I tried to use VRRP for the failover and the two machines switch properly when the master goes down.

Unfortunately i have an issue with pppoe-client sessions active on the master server. When the Master goes down the pppoe sessions don't deactivate on the client machines (RB750s). The PPPOE sessions remain idle (but active) on the clients and they switch on the backup PPPOE server only with manual intervention.
Dial-on-demand could solve part of the problem, but in some cases i'm forced to disable it...and the sessions "get stuck" on the master server even if it's no more available.

Is there a way to avoid this behaviour?...i need to let the pppoe sessions "know" that the master server went down and switch on the backup one.

Thanks in advance
Max

Hi Max.

Welcome to the forum. Lets see if we can quickly solve this one for you

Ok, so PPPoE is an L2 protocol so VRRP doesn't help you at all as far as redundancy is concerned. Simplest solution here is to simply place both servers in the same L2 domain (likely a single VLAN). Both will respond to customer queries. A quick review of PPPoE funcationality:

1) Customer device sends out a PADI essentially asking for any PPPoE server to respond
2) Each/Any/Alll PPPoE concentrators then respond with a PADO packet
3) The customer router then typically sends a PADR to the 1st PADO packet is received
4) The server then sends a PADS to confirm the session and off we go

So, under typical load scenarios one of the two servers (if identical) would have a 50/50 chance of being selected. As one server becomes more loaded it would typically respond slower allowing the less loaded server to respond first... so basic load balancing but 'luck' method.

If both servers then raise the routes upsteam and make use of RADIUS for auth you have a near perfect solution.

Hope that gives you some pointers?

*Karma is free*

Max, you come right with the issue?

you need to establish IBGP ir OSPF to announce the IP-Adresses between BGP-Router and your PPPoE-Serverss

Max,

You are referring to 2 separate redundancy issues and you should deal with them separately. First off - using BGP on a VRRP IP is messy at best and plain painful the rest of the time - I've had lots of debugging issue there before

I'd suggest the following setup:


If you control the upstream router then announce each /32 as it goes live. Otherwise configure /24 announce on both and simply use iBGP/OSPF between the 2 pppoe servers.