Hi,
Phil Howard wrote:
In effect Sprint is encouraging the waste of IP space. I'm putting together
a proposal now for a web farm type of facility for a group of investors and
a block of /19 is way more than is needed. But the plan is going to have at
least 4 points of multi-homing to diverse backbone providers, so a fully
announceable block is essential.
Idea: How about getting provider-dependent space from each one, then make
the web servers listen on different addresses each. Rig the DNS with a low
TTL for the server A records, or perhaps use dynamic updates (haven't tried
it yet though) to remove the IP from the A list if a link goes down.
Example you get space from:
ISP A 10.0.0.0/24
ISP B 10.1.0.0/24
ISP C 10.2.0.0/24
ISP D 10.3.0.0/24
So you have:
www.customer1.com IN A 10.0.0.1
IN A 10.1.0.1
IN A 10.2.0.1
IN A 10.3.0.1
www.customer2.com IN A 10.0.0.2
IN A 10.1.0.2
IN A 10.2.0.2
IN A 10.3.0.2
Now if ISP C goes down, delete 10.2.0.1 and 10.2.0.2 from the list.
Miguel,
Interesting. I haven't contemplated any aspect of your idea other than
nameserver restarts. With 30,000 domains hosted here, our nameserver
(which, according to the INTERNIC, is authorative for more domains than any
nameserver in the world) takes about 20 minutes to restart (it's an SGI
Challenge S). Our secondaries take a little longer.
That's with one A record per domain.
Restarting a nameserver every time a link gets sick is not an option, at
least for us.
Steve
Hi,
Phil Howard wrote:
In effect Sprint is encouraging the waste of IP space. I'm putting
together
a proposal now for a web farm type of facility for a group of investors and
a block of /19 is way more than is needed. But the plan is going to
have at
least 4 points of multi-homing to diverse backbone providers, so a fully
announceable block is essential.
Idea: How about getting provider-dependent space from each one, then make
the web servers listen on different addresses each. Rig the DNS with a low
TTL for the server A records, or perhaps use dynamic updates (haven't tried
it yet though) to remove the IP from the A list if a link goes down.
Example you get space from:
ISP A 10.0.0.0/24
ISP B 10.1.0.0/24
ISP C 10.2.0.0/24
ISP D 10.3.0.0/24
So you have:
www.customer1.com IN A 10.0.0.1
IN A 10.1.0.1
IN A 10.2.0.1
IN A 10.3.0.1
www.customer2.com IN A 10.0.0.2
IN A 10.1.0.2
IN A 10.2.0.2
IN A 10.3.0.2
Now if ISP C goes down, delete 10.2.0.1 and 10.2.0.2 from the list.
--
miguel a.l. paraz <map@iphil.net>
+63-2-893-0850
iphil communications, makati city, philippines
<http://www.iphil.net>