On Fri, 07 Sep 2007, Jay Vosburgh wrote: > Rick Jones <[EMAIL PROTECTED]> wrote: > [...] > >> Note that this out of order delivery occurs when both the > >> sending and receiving systems are utilizing a multiple > >> interface bond. Consider a configuration in which a > >> balance-rr bond feeds into a single higher capacity network > >> channel (e.g., multiple 100Mb/sec ethernets feeding a single > >> gigabit ethernet via an etherchannel capable switch). In this > >> configuration, traffic sent from the multiple 100Mb devices to > >> a destination connected to the gigabit device will not see > >> packets out of order.
I would just change the last part of the last sentence to: configuration, traffic sent from the multiple 100Mb devices to a destination connected to the gigabit device will not usually see packets out of order in the absence of congestion on the outgoing gigabit ethernet interface. If there was momentary congestion on the outgoing gigabit ethernet interface, I suppose it would be possible to get out of order delivery if some of the incoming packets on the striped round-robin interfaces had to be buffered a short while before delivery was possible. > The text probably is lacking in some detail, though. The real > key is that the last sender before getting to the destination system has > to do the round-robin striping. Most switches that I'm familiar with > (again, never seen one, but willing to believe there is one) don't have > round-robin as a load balance option for etherchannel, and thus won't > evenly stripe traffic, but instead do some math on the packets so that a > given "connection" isn't split across ports. Just FYI, the "i" series of Extreme switches (and some of their other switches) support round-robin load balancing. We consider this an extremely useful feature (but only use it for switch-to-switch link aggregation), and bemoan its lack in their newer switch offerings. Force10 switches also have a pseudo round-robin load balancing capability which they call packet-based, which works by distributing packets based on the IP Identification field (and only works for IPv4). One downside of the Force10 feature is that it is a global setting and thus affects all link aggregated links (the Extreme feature can be set on a per link aggregated link basis). -Bill - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html