Autoconfiguring level 2 visibility between subnets in a shared network?

John Hascall john at
Thu Jul 27 19:09:06 UTC 2006

> Gonzalo HIGUERA DÍAZ wrote:
> >I was wondering the following: given that a shared-network statement
> >group subnets that share a broadcast domain (or am I wrong here?),
> >wouldn't it be useful if a lease obtained for a host in one of those
> >subnets carried would include information about the rest of the
> >link-local subnets? In this way, a DHCP-enabled host in
> > would be able to talk at level 2 to hosts in
> > (asuming both subnets were defined in a shared-network
> >and really had level 2 visibility). ...

> It would require an option to configure client 
> routing which isn't standard and none of the 
> commercial dhcp clients request or support that 
> beyond 'default router'. 

Typically this is something that your router and the routing
agents on the clients would handle.  192.168.22.client would
send a packet destined for 192.168.33.other to 192.168.22.router
and in addition to forwarding the packet the router can send
a ICMP redirect back to 192.168.22.client telling it that it
can talk directly to 192.168.33.other -- so only the first
packet makes the extra hop.


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