Date: Sat, 9 Oct 1999 21:30:17 -0500 (CDT) From: Chris Dillon <cdillon@wolves.k12.mo.us> To: Mohit Aron <aron@cs.rice.edu> Cc: sthaug@nethelp.no, freebsd-net@FreeBSD.ORG, justin@apple.com, alc@cs.rice.edu, wollman@khavrinen.lcs.mit.edu Subject: Re: arp errors on machines with two interfaces Message-ID: <Pine.BSF.4.10.9910092046590.72645-100000@mail.wolves.k12.mo.us> In-Reply-To: <199910092137.QAA11776@cs.rice.edu>
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On Sat, 9 Oct 1999, Mohit Aron wrote: > > > - Because getting the advantage of this higher bandwidth requires special > > support (e.g. Fast Etherchannel or other forms of load balancing/bundling) > > that FreeBSD doesn't currently have in the standard configuration. It > > would require considerably more than just removing one error message to > > support this properly. > > > > > > What you're suggesting requires the following: > 1) Support in the switch for load-balancing incoming packets to the > multiple interfaces on the host (each having the same IP address). That is assuming you need the extra _incoming_ bandwidth, and not just outgoing. I use load-balanced links on our (cough) NT servers without having to set up anything at the switch. The NIC drivers assign the same MAC address to both (actually, up to 4) NICs. Data can be sent out any of the NICs and the switch will send the data to its proper location, that being the nature of the switch. Seeing the same MAC address on 4 ports, the switch sends incoming data to all four ports. I'm assuming for performance reasons that the NIC drivers ignore incoming data from all but one NIC. This happens to be done with a Intel dual 10/100, with the Compaq drivers (its a Compaq server), which appear to be just slightly modified Intel drivers. The drivers support manual failover, automatic failover, Fast EtherChannel, and "load-balancing without switch support" (which I am using). > 2) OS support for allowing same IP address to be present on multiple > interfaces. Or more precisely, the same MAC address. > Why go for the above costly solution when the same effect can simply be > achieved by connecting multiple interfaces with different IP addresses with the > vanilla OS ? Also as Julian remarked, many high-end servers already use the > configuration that I'm using. I'm not aware of any specs that conflict with > this configuration either. The solution would only be costly in terms of taking the time to actually implement it for FreeBSD. I would actually find it simpler, from an administrative standpoint, to assign one IP address balanced across multiple NICs than to assign multiple IPs to multiple NICs. One IP address also allows for greater bandwidth to a single host for a single transaction whereas the multiple-IP scheme doesn't (for example, you're connected at 4*100, and the other machine is on a gigabit link, and you're FTPing a file over). A question I have is, is this possible with all the different NICs that FreeBSD supports, or just a few different ones (due to hardware limitations)? -- Chris Dillon - cdillon@wolves.k12.mo.us - cdillon@inter-linc.net FreeBSD: The fastest and most stable server OS on the planet. For Intel x86 and Alpha architectures (SPARC under development). ( http://www.freebsd.org ) "One should admire Windows users. It takes a great deal of courage to trust Windows with your data." To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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