Date: Mon, 22 Mar 1999 11:45:59 -0500 From: "Gary Palmer" <gpalmer@FreeBSD.ORG> To: "Cyril A. Vechera" <cyril@main.piter.net> Cc: julian@whistle.com, cmsedore@maxwell.syr.edu, freebsd-net@FreeBSD.ORG Subject: Re: clustering/load balancing Message-ID: <60695.922121159@gjp.erols.com> In-Reply-To: Your message of "Mon, 22 Mar 1999 11:07:20 %2B0300." <199903220807.LAA06347@main.piter.net>
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"Cyril A. Vechera" wrote in message ID
<199903220807.LAA06347@main.piter.net>:
>
> in the original scheme 'single point of failure' is still present.
>
> +-------[Machine B]
> |
> [internet]-----[ any router ]----+-------[Machine C]
> |
> +-------[Machine D]
> ^^^^^^^^^
>
> or maybe you can see other way to connect 'internet' to Machine [B-C]?
There are many ways of doing it... Just very few ways that remove the SPoF all
the way to the host. HSRP'd routers and per-packet load balancing have reduced
a lot of the router based failures that could happen, but that still doesn't
remove the SPoF in the switch/hub between the routers and the hosts. As I said
in a previous message, Alteon have failover between switches, although it
probably requires their GigE cards to go to the host and have that work.
> what is the differense between 'any router' failures and 'balance
> dispatcher' failures?
I added a smiley to the end of the message for a reason. There are solutions
to most of the other SPoFs that are out there today. The biggest one still
left is actually not the one I highlighted, but rather:
+-------[Machine B]
|
[internet]-----[ any router ]----+-------[Machine C]
|
+-------[Machine D]
^^^^^^^^^^^^
Anyone know of any way to have redudancy all the way to the host? (i.e. 2 or
more NICs) Its going to need some daemon on the host watching the NIC for a
heartbeat or something, then sending out an ARP invalidation packet for the
(now failed) NIC and then another ARP for the (now working) NIC.
Gary
--
Gary Palmer FreeBSD Core Team Member
FreeBSD: Turning PC's into workstations. See http://www.FreeBSD.ORG/ for info
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