[olsr-dev] olsrd on multiple interfaces

Pawel Foremski (spam-protected)
Sun Sep 26 19:29:16 CEST 2004


On Sunday 26 of September 2004 17:48, Andreas T√łnnesen wrote:
> The patch looks ok(at first glance) and I can implement something
> similar for 0.4.8... However - this sounds like a strange setup to me -
> multiple devices using the _same_ IP address sounds like something that
> would mess up your regular IPv4 routing if these devices are not just
> something available to the upper layers.

Why? Sometimes such setup is needed - why to limit olsrd usability only to 
interfaces with different IP addresses? I'm currently running the patched 
olsrd on 3 boxes which have multiple interfaces with one IP and it doesn't 
break anything - just works.

> Some questions that pops up: 
> Isn't the 4 ethernet ports on the WRT in reallity a layer2 switch?

Yes, it is by default.

> Can't 
> the switch device be accessed as one interface since all ports are using
> the same address?

1. Even if I were using all ports as switch, there is also the WiFi interface 
- eth1, which I also need to run olsrd on.
2. I need all ports to be separated (security, flexibility, more control, 

> How does you routing table look(having four devices 
> set up within the same subnet) - and on what ports are a regular
> broadcast ( routed?

All interfaces have netmask and broadcast set 

> Are the vlan devices layer2 tagging 
> devices(VLAN) - or just some way of accessing the individual ports?

Well... both? :)

> Does 
> the patch fix your problems(the sockets bind ok to the vlan devices?).

Yes, it does completely. There was no problem (in stock version) in binding on 
multiple interfaces, only in adding a discovered route "on wrong interface".

> To me it seems that a routing protocol should
> consider the switch _one_ interface, not four.

As I wrote - even if vlan1 to vlan4 were considered as eg. vlan0, there is 
always eth1. And apart of that, I also can't bridge all of my interfaces due 
to security reasons.

Kind regards.

Pawel Foremski

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