Date: Wed, 6 Oct 1999 09:56:37 +0100 (MET) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: dennis@etinc.com (Dennis) Cc: hackers@FreeBSD.ORG Subject: Re: ARPs on a bridge Message-ID: <199910060856.JAA12460@labinfo.iet.unipi.it> In-Reply-To: <199910051825.OAA07146@etinc.com> from "Dennis" at Oct 5, 99 01:24:30 pm
next in thread | previous in thread | raw e-mail | index | archive | help
> >> Is there a way to force a Freebsd system to route to the same logican IP
> >> network rather than send a redirect?
> >>
> >> The situation occurs with segmented bridges where customers on the same
> >> logical IP network are on separate bridge groups. When trying to reach one
> >> another, they are getting redirects however they are not permitted to arp
> >> across groups.
... (long explaination moved to the end)...
I think i don't understand the architecture of the system, so could you
explain a bit more about that -- i would like to learn more about
this. How many physical and logical interfaces does the FreeBSD
system see ?
From your description this is what i understand:
customer ----[ DSL bridge ]------+----[ main router ]-- rest of net.
|
customer ----[ DSL bridge ]------+
|
repeat 150 to 900 times | shared frame relay without
| multicast/broadcast support
customer ----[ DSL bridge ]------+
and the understanding is that the 'DSL bridge' is perhaps implemented
with a FreeBSD-based box with an ethernet on the customer side and a
suitable card on the other side.
Now if the DSL bridge is "almost" a bridge (in the sense that it filters
broadcast traffic) then your architecture "almost" works (except
when operation depends on traffic that you filter) and you need a
separate mechanism to implement the functionality killed by the
filtering. E.g. recognize that some broadcasts (e.g. ARP) are special
and need to be forwarded anyways...
cheers
luigi
> On a DSL bridge you have 150 to 900 customers bridged on a relatively low
> bandwidth line (frame relay in this case). Forwarding broadcast traffic is
> very undesireable as you have to replicate the packet 900 times, and since
> you know the IP assignement for the DLCI you dont need to forward it to
> everyone. Each customer is on a different bridge group so traffic cannot be
> bridged between them, so you have to route, but you dont want to have to
> allocate a subnet to each bridge group either. The problem is that, from
> the FreeBSD boxes view, you are routing to the same logical net (assuming
> that all of the bridge groups are in the same IP space.
>
> We're not talking about bridging a couple of ethernets here.
>
> Dennis
>
>
> To Unsubscribe: send mail to majordomo@FreeBSD.org
> with "unsubscribe freebsd-hackers" in the body of the message
>
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199910060856.JAA12460>