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List:       netbsd-tech-net
Subject:    Re: NetBSD vs Microsoft NLB
From:       Stephen Borrill <netbsd () precedence ! co ! uk>
Date:       2016-09-20 16:13:45
Message-ID: Pine.NEB.4.64.1609201708570.524 () ugly ! internal ! precedence ! co ! uk
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On Tue, 20 Sep 2016, Michael van Elst wrote:
>> Microsoft Network Load Balancing is similar to carp(4). You have a shared
>> address which is handled by multiple hosts. Whenever there isn't an ARP
>> entry you get an error when connecting to the shared address with ftp(1).
>
> Wasn't Microsoft abusing a multicast MAC address for this?

Unicast vs Multicast vs IGMP Multicast is an option when setting up the 
cluster.

Anyway, I think this thread can be ignored; it turns out that one alleged
member of the cluster had decided to no longer be a member and to instead 
put the cluster IP address as an alias on one of its NICs. The upshot was 
that the arp request was getting two responses from different machines 
which unsurprising broke TCP as it switched hosts in the middle of the 
connection.

-- 
Stephen

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