[OLSR-users] Anyone tried two nodes with internet connection?

Rajesh Narayanan (spam-protected)
Fri Jan 12 06:55:41 CET 2007


Hi Tim,

Not sure if this is going to work, I'll try it when I get to work tomorrow
though. But need to try the script first.

But here is the conclusion I have come to (maybe because of my own limited
knowledge). I dont think any other hack other than removing the default
route is going to work, since that is at the core of the issue. The default
route takes precedence so one will have to delete the default route.

But since its been deleted, it needs to be added back so as to check if its
working after some time and test the ping via the default route. If it
works, then great; if not, then it needs to be deleted again.

Its a nasty hack, but thats the nature of routing unless and until we do
something else. I'm running out of ideas quite fast though and I need to
prototype this asap :-(  .

Thanks,
Rajesh.

On 1/11/07, Tim Martin <(spam-protected)> wrote:
>
>  Here's a bad hack I was thinking of, but I use pfSense as my OLSR dynamic
> gateway and I'm not sure if this is possible with your setup.
>
> Set node A to ping a specific address.  On node B block any access to that
> same address.  So if node A goes out then the ping won't go through node B
> and falsely announce node A as a working gateway.  Of course, do the same
> with a different ping address on node B which is blocked by node A.
>
> Also, I think that if you can use pfSense www.pfsense.com you can set it
> to have dual WANS and it has OLSR built into it.  This might be a better
> solution for your network.
>
> Tim
>
>
> Rajesh Narayanan wrote:
>
>
>
> On 1/11/07, Bernd Petrovitsch <(spam-protected) > wrote:
> >
> > On Thu, 2007-01-11 at 12:25 -0800, Rajesh Narayanan wrote:
> > > :-)
> > >
> > > This is precisely the question that I have been myself thinking since
> > > yesterday. I thought of going back to routing fundamentals to see if
> > > there is a good answer. So far I have not been able to think of
> >
> > Actually Andreas delivered the two possibilities in his answer. One is
> > below and the other is: Take dedicated nodes for this.
>
>
> ************ sorry if im starting to sound silly :-), but I didnt
> understand this one.
>
>
> >  anything except a 'not so clean hack' that would sound soemthing like
> > > this:
> > >
> > > 1. Write a script to ping (dyn-gw already does this) on the default
> > > WAN interface.
> > > 2. If Pings succeed dont do anything
> > > 3. If ping fails then delete the default route.
> > >     - This is the part you were talking about. HOW DO I RECOVER??
> > >     - Since if I delete the route then the pings are not going out of
> > > this interface anyways.
> >
> > The other solution (see Andreas email) is to add (low priority) host
> > routes to known-outside ping targets - the ones which are used to decide
> > if we have an uplink or not.
>
>
> **********  this does not help. The issue is with the static route that
> gets added when the uplink is discovered. Once its discovered and the static
> default route gets added, no amount of dancing with olsrd or the dyn-gw
> parameters will be useful.
>
>
>
> > 4. The hack is as follows:
> > >     - every 5 mins add the default route.
> > >     - test ping through that interface
> > >     - if successful then leave it
> > >     - else, delete the default route again.
> > >
> > > I know this is BAAAAAAAAAAAD, but all I want is that I should use the
> >
> > I (also) have some bad feelings about this:
> > IMHO this is not very robust (e.g. what happens if olsrd exits somewhere
> > in between - it could be a `kill -9` from the outside). Since OLSRD runs
> > on embedded hardware, no user action can be expected (let alone
> > enforced) so it must work fully automatically (at least in theory we
> > have o bugs in implementations;-).
> >
> > And I assume that OLSRD doesn't announce that link during the test.
>
>
> ********** I just want to prototype this to showcase a possible network
> topology so a bad hack is hopefully ok for now. I realize there may be
> better ways of doing it. But my coding skills are pretty rusty right now so
> scripting is the best choice for me now :-)
>
> Thanks,
> Rajesh
>
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