[quagga-users 13456] RES: RES: Re: OSPF with Quagga and CARP - Problem with NextHop

Andre Luiz Paiz - Instituto de Química - Unicamp andre.paiz at iqm.unicamp.br
Thu Sep 26 13:12:35 BST 2013


Hi, thanks for the answer.
If I set up CARP on the external interface, configure the same settings in
quagga for both servers and only starts the service when backup becomes
master, will work?

I can´t run BGP.

If I run CARP on the WAN interface, will quagga point advertised routes to
my virtual IP? If yes, I guess that will be my choice.

Thanks.
Andre

-----Mensagem original-----
De: Alexis Rosen [mailto:quagga-users at alexis.users.panix.com] 
Enviada em: quarta-feira, 25 de setembro de 2013 20:06
Para: Andre Luiz Paiz - Instituto de Química - Unicamp
Cc: 'Christian Franke'; quagga-users at lists.quagga.net
Assunto: Re: [quagga-users 13454] RES: Re: OSPF with Quagga and CARP -
Problem with NextHop

There are two things that you could/should be doing that would make your
life a lot easier.
1) Run OSPF on both of your hosts all the time, not just when CARP starts
it.
2) Run BGP, and not OSPF.

But, if you can't do either... Your config is not clear enough to diagnose.
What interface is failing, to prompt CARP to switch to backup? Presumably
the internal, since you said it's running only there. But in that case, if
the external interface is still up, your upstream will still see that
adjacency.

In one case we had a problem like this, but with BGP, because our neighbor
was mismanaged. In the end, all we could do was run VRRP facing them, using
a fake MAC address which we would move between hosts along with the IP
address. If you did the same thing it would probably work. And you probably
wouldn't need to play MAC games.

/a

On Sep 25, 2013, at 6:40 PM, Andre Luiz Paiz - Instituto de Química -
Unicamp <andre.paiz at iqm.unicamp.br> wrote:
> Hi Christian.
> Thanks for the answer.
> 
> My ISP has provided me the log for the show ip ospf route command:
> 
> sh ip ospf route 143.X.X.0
> 
>      Destination     Mask            Path_Cost Type2_Cost Path_Type
>      143.X.X.0    255.255.255.192 1         200        Type2_Ext
>      Adv_Router      Link_State      Dest_Type State      Tag       Flags
>      143.X.X.15    143.X.X.0    Ase       Valid      0          1800 
>      Paths Out_Port        Next_Hop        Type      State    
>      1     ve 3            143.X.X.11    OSPF      00 00
> 
> 
> Watch that the backup is advertising (.15 IP) but the nexthop is the 
> master IP (.11)
> 
> How can I provide more info for you to help me with that. Do you need 
> my LSDB? I don't think my ISP will provide me an entire database.
> 
> My configuration is very simple. Just setting a nssa area, configuring 
> static routes for my internal networks and redistribute with 
> "redistribute static metric 1". Just that!
> 
> Thank you
> Andre
> 
> -----Mensagem original-----
> De: Christian Franke [mailto:nobody at nowhere.ws] Enviada em: 
> quarta-feira, 25 de setembro de 2013 18:34
> Para: Andre Luiz Paiz - Instituto de Química - Unicamp
> Cc: quagga-users at lists.quagga.net
> Assunto: [quagga-users 13453] Re: OSPF with Quagga and CARP - Problem 
> with NextHop
> 
> On 09/25/2013 09:42 PM, Andre Luiz Paiz - Instituto de Química -
>> Does anyone have an idea about this? Should I offer a better metric 
>> from the backup? But if I do that, I believe that the failback will 
>> not
> work.
> 
> It's a bit hard to tell from the information you provided. To debug 
> that you may want to have a look into the OSPF LDSB. (You can do that 
> with "show ip ospf database", you can also display more detailed 
> information by specifying the LSA type there)
> 
>> When QUAGGA is off on the master, shouldn't the neighbours know that 
>> the old nexthop don´t exist anymore?
> 
> The information that was advertised by your failed master may be kept 
> by the other OSPF routers for up to one hour, that is to save some 
> update traffic should your master come back online during that timeframe.
> 
> However, the neighbors should notice that your master has failed as 
> it's no longer sending hello-packets. They will propagate that 
> information through the OSPF domain and all routers should update 
> their routing table accordingly.
> 
> -Christian
> 
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