Re: [dhcwg] draft-ietf-dhc-dhcpv6-opt-netboot-05 - how to proceed?

["Woundy, Richard" <[e-mail]>]

> That said, it is not clear to me that load balancing is actually a
requirement that needs solving. At least not for preboot loading.

I don't have any personal interest in this netboot approach, but I can
understand why load balancing could be interesting to the netbook folks.
After a power outage, I can imagine a lot of devices simultaneously
rebooting, and therefore there may be a much higher load of netboot
traffic. At the same time, one might not want to purchase lots of
netboot servers for a once-a-year power outage event.

-- Rich

-----Original Message-----
From: [e-mail] [mailto:[e-mail]] On Behalf
Of Thomas Narten
Sent: Thursday, October 22, 2009 2:14 PM
To: [e-mail]
Subject: Re: [dhcwg] draft-ietf-dhc-dhcpv6-opt-netboot-05 - how to
proceed?

I am opposed to relying on DNS round robin as the
default/best/recommended approach to do load balancing when booting.

Round Robin DNS load balancing is not officially supported in the IETF
because the only way you can get it to work properly is to disable DNS
caching (i.e, use TTLs of 0) so that a query always goes back to a
server than can explicitely modify the ordering. But disabling caching
has negative implications for DNS performance, reliability, etc. You
then also have to have specially modified servers (that reorder
results based on various criteria) that are again not officially
blessed by the IETF.

The IETF DNS WGs have discussed this many many times, and have so far
not been willing to bless such load balancing. I do know that it is
used in some environments and can be a useful tool at times.

If it is a requirement that remote booting include support for load
balancing, I think we need to first make note of that and develop a
proper solution. There are number that could work that are fairly
simple (e.g., consider the DNS SRV "weight" mechanism).

That said, it is not clear to me that load balancing is actually a
requirement that needs solving. At least not for preboot loading.

Comments?

Thomas
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