AW: default route via OSPF depending on the ISP

[Rohrmann Sascha]

Hi Ondrej,

>> Do you have more information and/or tips for me, by chance? 

> As others wrote, you could do periodic pinging by e.g. fping and enable/disable a static 
> protocol using birdc (birdc disable XXX). 
> See the attached script, which does something like that and estimating packet loss.

Thank you very much for that script.

I have two additional questions about this:

1)	Why do you stop the whole routing process if the ISP is down? 
	Isn't there a chance to "only" stop distributing the default-route and keep the OSPF process?
	If yes, how am I able to realize that?
2)	If 1) isn't possible, is there a way to check and count incoming routes from eBGP so that the router sees that
	the connection works and distributes the default-route after the check?

My goal is to only stop distributing the default-route and not to kill any routing-protocol such as OSPF.

Thanks in advance. 

-----Ursprüngliche Nachricht-----
Von: Ondrej Zajicek [mailto:santiago at crfreenet.org] 
Gesendet: Samstag, 5. Dezember 2015 16:34
An: Rohrmann Sascha
Cc: bird-users at network.cz
Betreff: Re: default route via OSPF depending on the ISP

On Thu, Dec 03, 2015 at 03:12:10PM +0000, Rohrmann Sascha wrote:
> > Well, you could use static default-route and 'check link' option, but that will help you only in the third case, not in the second one. 
> > For the second case, you must have some other way to establish 
> > whether ISP is up or down, either by running some routing protocol between you and ISP, or running BFD session.
> 
> Just as you said, that will only help me in the third case. 
> In which way should BFD be able to accomplish my goal?
> In my understandings BFD only checks if the link is available. If this isn't given, BFD tells Bird this problem.

BFD checks whether specified/destination IP is available (but it also must run BFD).
Therefore both link and host must be up.


> Second problem is, not every ISP supports BFD yet because BFD is kinda new. 

That is true, and also BFD-controlled static routes are only in devel version of BIRD, not in v1.5.0


> I was thinking about a simple ping which checks the availability of the opposite party. 
> Am I able to include a simple shell script in bird? 

No


> Do you have more information and/or tips for me, by chance? 

As others wrote, you could do periodic pinging by e.g. fping and enable/disable a static protocol using birdc (birdc disable XXX). See the attached script, which does something like that and estimating packet loss.


> > I was thinking about the bfd protocol, but bfd is kinda new and you can't run more than one instance in bird.
> > Well, is there any reason why to run multiple BFD instances in BIRD?
> 
> Well... you could create one bfd instance for one single interface.
> Furthermore you could then check the availability for e.g. my problem instead of checking all BFD instances.

I don't understand here.


-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
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"To err is human -- to blame it on a computer is even more so."