Date: Wed, 06 Oct 1999 12:01:37 -0400 From: Dennis <dennis@etinc.com> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it> Cc: hackers@FreeBSD.ORG Subject: Re: ARPs on a bridge Message-ID: <199910061702.NAA10711@etinc.com> In-Reply-To: <199910060856.JAA12460@labinfo.iet.unipi.it> References: <199910051825.OAA07146@etinc.com>
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At 09:56 AM 10/6/99 +0100, Luigi Rizzo wrote: >> >> 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 ]------+ each DLCI is modeled as a PTP connection, so the system sees a physical interface for each channel. The bridge software just sees then as bridged interfaces. the "right" way to do it is to allocate a subnet to each bridge group, as different bridge groups cant talk at the mac layer by design. Im just trying to come up with an easy solution to free up addtional IP space so customers with only 2 address dont have to get a whole subnet. dennis > >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
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