Date: Thu, 17 Feb 2005 20:16:42 -0800 (PST) From: Henry Su <henrysu@nttmcl.com> To: Jon Noack <noackjr@alumni.rice.edu> Cc: delphij@delphij.net Subject: Re: Two NIC's connected to same subnet: routing question Message-ID: <20050217201208.S13851@yarn.nttmcl.com> In-Reply-To: <421501A0.3040707@alumni.rice.edu> References: <EEECKDGGIOMGJDPILFBBIEKHEDAA.henrysu@nttmcl.com> <421501A0.3040707@alumni.rice.edu>
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On Thu, 17 Feb 2005, Jon Noack wrote: > Henry Su wrote: > > You can configure both NIC as /32. You also need proxy arp installed and > > listen on both NIC. Then the traffic should be able to follow between two > > NICs. Since Proxy ARP always answers its MAC to clients, so the clients can > > always send traffic to em1 or em0. Based on client's mac entry in the ARP > > table, client to client traffic is easily transferred. Other traffic should > > be able to direct to default gateway. > > I gave this a shot and failed miserably. Admittedly, I know > little-to-nothing about arp, so hopefully it's obvious why I failed. > > I have this in my /etc/rc.conf: > network_interfaces="fxp0 fxp1 lo0" > ifconfig_fxp0="inet 10.0.0.4 netmask 255.255.255.255 link0" > ifconfig_fxp1="inet 10.0.0.5 netmask 255.255.255.255 link0" > defaultrouter="10.0.0.1" > > Created an arp table file called /etc/arp.table (built-in dual fxps so > the macs are actually consecutive): > 10.0.0.4 00:01:02:03:04:06 pub > 10.0.0.5 00:01:02:03:04:05 pub > > And had this in /etc/rc.local: > /usr/sbin/arp -f /etc/arp.table > This is because you do not need these 2 entries in it, fxp0, fxp1 are two interfaces in your machine, so their mac is of course known by the system. You need a proxy arp server to listen on fxp0, and fxp2. > On boot I ended up with the following error message and a blank arp table: > set: proxy entry exists for non 802 device > > Do I need to add in some static routes to make this work? What am I > missing? > > Would this make it possible to have each adapter/IP use a different > gateway? I ask because I have 2 T1s and I'm curious if a single machine > could utilize both. It's an SMP box so I was thinking of running 2 > peered instances of Squid on separate IP addresses with each IP address > using one of the T1s as the gateway. That way I could force my power > users through one connection and everyone else through the other while > still gaining the benefit of caching everything for everyone. It's > probably needlessly complicated, but it sounds fun... ;-) > > Jon > > > -----Original Message----- > > From: owner-freebsd-net@freebsd.org > > [mailto:owner-freebsd-net@freebsd.org]On Behalf Of Xin LI > > Sent: Tuesday, February 01, 2005 10:12 AM > > To: freebsd-net@freebsd.org > > Subject: Two NIC's connected to same subnet: routing question > > > > > > Dear folks, > > > > I think I got confused with the routing problem we will have when at > > least two NIC's are connected into the same subnet. > > > > The scenario: > > em0: 192.168.0.1/24 > > em1: 192.168.0.2/24 > > > > We can't simply configure like this, since 192.168.0.0/24 network route > > exists as soon as either em0 or em1 is up. A workaround for this is > > that we assign 192.168.0.2/32 for em1, but that has another issue that > > all traffics will go through em0 for "outgoing", say, outside the > > current network. > > > > A google of the issue has indicated that the "Move ARP out of routing > > table" work done last April should have resolved this, as "With this > > change it is possible to have more than one interface in the same IP > > subnet and layer 2 broadcast domain.". However, what I have found from > > our mailing list archive says only to assign /32 IP address, or remove > > routing item from route table, which is essentially identical to the /32 > > solution. > > > > So is there any way to utilize the both NIC's? I think I have been > > confused :-( > > > > Cheers, > > -- > > Xin LI <delphij delphij net> http://www.delphij.net/ > >
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