AW: default route via OSPF depending on the ISP

[Rohrmann Sascha]

> 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.

Second problem is, not every ISP supports BFD yet because BFD is kinda new. 
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? 
E.g.:
=======================
Include ping.sh   (ping check)
If (ping.sh = 1)
{
	export 0.0.0.0/0 via eth0;
}
=======================

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

> 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.

Regards :)

-----Ursprüngliche Nachricht-----
Von: Ondrej Zajicek [mailto:santiago at crfreenet.org] 
Gesendet: Donnerstag, 3. Dezember 2015 16:00
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 02:34:02PM +0000, Rohrmann Sascha wrote:
> Dear users of the Bird internet routing  daemon,
> 
> First of all I am sorry for my e-mail which I have sent some minutes before.
> It was a mistake and you can ignore my last mail.
> 
> Now to my question:
> 
> I want my OSPF to distribute the default-route ONLY and ONLY if the ISP is available.
> Means, if the link, or the IP isn't available, my OSPF should be quite.
>
> Further information:
> 
> ISP                         (ISP is up)
>   l                            (Link is up)
> R1                          (Interface is up)
> 
> R1: everything is ok, I can reach the ISP, so I am the default-gateway for everybody below me.
> 
> ISP                         (ISP is down)
>   l                            (Link is up)
> R1                          (Interface is up)
> 
> R1: Oh gosh! The ISP is down! I am now no longer the default-gateway for everybody below me.
> 
> ISP                         (ISP is up)
>   l                            (Link is down)
> R1                          (Interface is up)
> 
> R1: Oh, I can't reach my ISP... Ok, I need to stop telling everybody below me I am the default-gateway.

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.


> 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?


--
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org) OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net) "To err is human -- to blame it on a computer is even more so."