Re: default route on other subnet

[buhrow%lothlorien.nfbcal.org@localhost (Brian Buhrow)]

        Hello.  So unless I'm really not understanding what's going on, I
wouldn't expect your example to work.  A bridge is not a router.  What I
mean by that is that a bridge cannot move a packet from one IP subnet, i.e.
10.1.1.0/24 to another, 10.2.2.0/24.  Instead, what I suggest is something
like:

1.  Define an interface on the bridge on Dom0 and give it an IP address of
10.1.1.254/24

2.  On your guest domU, give its interface an address of 10.1.1.2/24

3.  On the guest domU, set the default route to 10.1.1.254

4.  If you want the guest domU to manage a 10.2.2.x subnet inside itself, 
something
I find hard to imagine, but hey, I'm not really that creative, define  a
new interface in the domU and give it an address of 10.2.2.1/24.

5.  Then, set a route on Dom0 like:
route add 10.2.2.0/24 10.1.1.2

        That will cause the Dom0 to send packets destined for the 10.2.2.x
subnet to the DomU on 10.1.1.2.

Hope that helps.
-Brian

On Sep 30,  9:23pm, Pierre-Philipp Braun wrote:
} Subject: Re: default route on other subnet
} Quoting Brian Buhrow 30/09/2011 17:24,
} >     Ok.  Is it possible to give the NetBSD DomU, under the Linux Dom0 a
} > public address which attaches to a bridge which connects to the real
} > ethernet of the Linux external interface?  If so, then you could use pf or
} > ipfilter on that NetBSD DomU to do  the filtering you want.  Or, perhaps, I
} > don't understand your problem?
} 
} Yes that's the bridge config which I'm actually trying out but the 
} gateway, although it's reachable from the network interface hence the 
} bridge (there's even a rule to accept my guest's mac address), doesn't 
} respond.  That's the problem.  There's some arp issues involved and I 
} don't know where they lie-in in exactly.  But my situation proves the 
} limits of linux/netbsd compatibility in a xen environment on linux dom0s 
} (which I quite high, I must say, everything's fine apart ffs log and this).
} 
} As an example, in a bridge configuration, say I've got 10.1.1.1/24 on 
} the dom0 and I want 10.2.2.2/24 on the guest.  And the gateway is 
} 10.1.1.254.  The procedure from the networking FAQ should do but I get
} xx:xx:xx:xx:xx:xx tried to overwrite permanent arp info for 10.1.1.254
} repeatedly.  Where xx:xx... is the mac address of the gateway.
} 
} On the dom0, peth0 and eth0 (the name of the bridge in fact) both have 
} network interface's mac address.  peth0 has no IP while the bridge, 
} eth0, gets the dom0 IP.  The vifs get FE:FF:FF:FF:FF:FF and no IP.
} 
} Thanks
} Pierre-Philipp
>-- End of excerpt from Pierre-Philipp Braun