Date: Mon, 21 Aug 2000 22:19:09 -0700 From: Emmanuel Gravel <egravel@earthlink.net> To: "Larry Skarpness Jr." <larry@chainsoft.com> Cc: <freebsd-questions@FreeBSD.ORG> Subject: Re: ARP issues with 2 or more multi-homed interfaces on same physical LAN Message-ID: <200008220514.WAA24408@avocet.prod.itd.earthlink.net> In-Reply-To: <004a01c00be8$9cdc5ee0$0a00a8c0@chainsoft.com> References: <Pine.BSF.4.10.10008220246190.2305-100000@parmenides.utp.net>
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You're better off just running a null hub cable between the cable modem and the first interface on your dual homed system, and keep the others, which are your internal network, on your hub. Keeps it cleaner since your gateway system still needs to do NAT with the other machines (so the packets go on the hub at least twice instead of just the once). I have a similar setup and it works like a charm, using FreeBSD 4.1 circa Mon Jul 17 20:04:10 MST 2000. Your setup can actually leave fairly big holes to someone who knows how to use them. Plus, a null hub isn't hard to do (you should have gotten one from them anyway). Moral of this story, separate your networks with more than just TCP/IP. You'll get better performance out of it anyway. Good luck! At 08:25 PM 8/21/00 -0700, Larry Skarpness Jr. wrote: >Janko, > >Thanks for the quick response. Allow me to clarify the situation. The NICs >have different IPs, different networks, and differenct ethernet addresses. >They just happen to be connected to the same network hub. Obviously this is >a somewhat unusual configuration. The OS detects this situation as it >should, however it spews warning messages constantly when just one would be >enough. > >Some might be asking why would you want to do this in the first place. I am >situtuated on a cable modem. The ISP has supplied two completely different >IPs and different networks through this one cable modem. The ISP severly >limits the upload bandwidth, even between IPs on networks within their >control. So I have also multi-homed these two machines to another private >local network on which other machines exist. NAT is also being used on one >of the public IPs to support other machines on the private network. All of >these machines and the cable modem are wired into the same network hub, as >there is no reason to physically seperate them. Through this mechanism all >the machines can reach eachother on the private net, and get out to the >internet. > >Machine 1 has > NICA HUB1 > IPA NETA (cable modem1) supports NAT to outside > NICB HUB1 > IPB NETB (local1) >Machine 2 has > NICC HUB1 > IPC NETC (cable modem1) > IPD NETB >Machine 3 has > NICD HUB1 > IPE NETB >Cable mdem 1 on HUB1 > >I think this is a valid configuration. Machine 1 complains that ARPs on >NICA are picked up on NICB, which in this situation would be expected. Is >there some reason why the FreeBSD OS must be so noisy about it? I WANT two >or more NICs in the same machine on the same physical network. The hack I >made to if_ether.c forces the OS quiet about it. Others are in the same >situation and would probably like this option without the neccessity to >hack. > >Larry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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