[OLSR-users] Re: [olsr-dev] olsrd on multiple interfaces
Sun Sep 26 21:56:57 CEST 2004
On Sunday 26 of September 2004 19:53, Andreas Tønnesen wrote:
> The concept of IP routing is based on the fact that one has an unique
> outgouing interface for a given IP address. If you set up multiple
> interfaces and add the same route through these this would mess up the
> whole IP routing basics. If i set up a box with two interfaces eth0 and
> eth1 and add the route 192.168.10/24 to both of them - then chances are
> that all traffic destined for that network will end up being routed
> trough the interface with the first entry in the routing table. This is
> IMO not because the routing mechanism lacks some feautre - but because
> the whole setup is bad.
Well, I know that normally each interface should have different IP address,
but as I said sometimes it's useful to use only one IP address for one
machine - for example just for easiness and simplicity :).
> > 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.
> Are you saying that _all_ physical devices use the same IP address? The
> WLAN, eth and switch??
> If not (...)
> > 2. I need all ports to be separated (security, flexibility, more control,
> > etc..).
> Ok - this is where you need to convince me with more arguments. Why is
> this separation of ports on a switch needed on the _routing_ layer?
I'm building a wide wireless network with Internet access. I use WRT54Gs to
build my backbone - some of them are connected by WiFi and some by Ethernet.
Then, I run PPPoE on some interfaces ("access" interfaces) to be sure that
only registered users can connect. The interface(s) PPPoE is running on can't
forward traffic - only PPP interfaces created by PPPoE sessions are allowed
I divided all of the interfaces available on WRT54G to "backbone" and "access"
- "backbone" connects to WRT54Gs and "access" will have some Access Points,
hubs or switches connected. Because some interfaces are trusted and the other
not (especially these with "open" Access Points) I must separate them.
> >>How does you routing table look(having four devices
> >>set up within the same subnet) - and on what ports are a regular
> >>broadcast (10.2.255.255) routed?
> > All interfaces have netmask 255.255.255.255 and broadcast 10.255.255.255
> > set up.
> Ok - so you've got something like
> DST IFACE
> 10.2.0.0 vlan1
> 10.2.0.0 vlan2
> 10.2.0.0 vlan3
> 10.2.0.0 vlan4
> in your routing table?
On Sunday 26 of September 2004 21:16, Andreas Tønnesen wrote:
> Ups... seems I overlooked the fact that your interfaces were set up with
> a netmask of 255.255.255.255. Please disregard the suggestion of the
> routingtable that I gave. I guess there is no arrgegated routing done
> via these interfaces.
Yes, you're right.
> >>Are the vlan devices layer2 tagging
> >>devices(VLAN) - or just some way of accessing the individual ports?
> > Well... both? :)
> Ok - are using different 802.1q tags for every port on the switch?
Yes. Practically each port is one 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.
> I'm not saying you should bridge your interfaces.
I know :), just a word about possible work-around...
> OLSR works fine on
> multiple interfaces if the prequesite that all interfaces use uniqe IP
> addresses is fulfilled - which I again belive is a basic of IP routing.
> The problem here is that you are using multiple interfaces configured
> with the _same_ IP address. What I am saying is that olsrd should IMO
> run on your etherneth interface(beein the "Internet port" on the WRT),
> you WLAN interface and your switch(the switch as _one_ device).
I know, I know, I know :). I'm not trying to deny any of networking
principles. In my situation it's just the best to assign one IP address to
the box, not to a particular interface. I noticed olsrd doesn't support it,
wrote a patch and sent it - that's all. I don't want to explain all of my
intentions, as this mailing list isn't about it :). I know what I'm doing and
that it's not the "perfect way". Just thought it might be useful - if not -
just ignore it - it's your project.
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