Date: Tue, 21 Nov 2000 08:08:00 +1300 From: David Preece <davep@afterswish.com> To: freebsd-hackers@freebsd.org Subject: 802.1q, bonding and mpath Message-ID: <5.0.0.25.1.20001121080718.00a7b910@pop3.i4free.co.nz>
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[tried on -questions, will try -hackers, apologies to those who are on both] I just spent the afternoon trying to work out if channel bonding / etherchannel / trunking is possible on FreeBSD. The answers from the mailing list archives say either: 1, Nope. 2, Yup, but it's messy and you have to use PPPoE. 3, Yup, use a kernel hack called mpath. Note that (possibly due to a bad ISP) flirble.org, where mpath should be, appears to be currently unavailable so I'm slightly clue disabled at the moment. None of this seems to answer what, for me, appears to be the basic question: When a client machine ARP's for the servers IP, it has to reply with a link layer (i.e. ethernet MAC) address. All packets from client to server (or nearest router to server) then travel between these two MAC addresses. How does this work with two network cards then? Either: a, Both network cards have the same MAC address, but then how does the switch know which card to send an incoming packet to? This appears to be the approach taken by mpath since "the ARP request is replied by the head of the cluster" (pseudo quote, sorry). Is this something the switch has to understand? b, The cards have different addresses and the ARP reply is cooked such that it comes from one or the other card - like round robin DNS, only for layer 2. This is all well and good, but the next hop router would have an ARP cache, so presumably all connections would go to one card or the next. c, None of the above. I also don't get the connection with 802.1q VLAN's. 802.1q appears to be about marking ethernet packets with a VLAN number such that your one LAN can be considered to be many LAN's electrically isolated. Great, I've even used it on a cisco switch and it worked a treat. I cannot find it's connection with the trunking/bonding problem though... Dave To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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