Load balancing, setting up 2 IP addresses for the same website...

Pete Tenereillo pt_bind at hotmail.com
Wed Sep 8 14:02:43 UTC 2004


Well, I don't agree with this:
>> Or you could pay a significant amount of money to put
> together a *true* load-balancing solution
Umar needs to load balance 2 links to one server, not "n" servers at one 
location (so he doesn't need an SLB switch), and he says he needs failover 
for HTTP clients between those links. Therefore as described in 
www.tenereillo.com/GSLBPageOfShame.htm, he can't do better than simple load 
sharing with 2 A records, regardless of how much money he throws at it (to 
spend time ordering A record responses only adds latency, the order is lost 
anyway, i.e. the free solution is actually _better_ than the expensive one).

Yahoo is in a different situation. With 35 or so data centers Worldwide, 
Akamai can return the best "few" Yahoo A records for that client and let the 
client go to whichever of those few, totally (and intentionally) out of the 
control of the fancy geographic load-balancing solution.


Pete.

PS What I've heard is that when people post questions like this, they get 
mail-bombed with replies from companies trying to sell stuff to them (in 
this case it would be inbound link load balancers). Just doing my part to 
help strike a balance.


----- Original Message ----- 
From: "Kevin Darcy" <kcd at daimlerchrysler.com>
To: <comp-protocols-dns-bind at isc.org>
Sent: Tuesday, September 07, 2004 9:02 PM
Subject: Re: Load balancing, setting up 2 IP addresses for the same 
website...


> Umar Pirzada wrote:
>
>>Hi
>>
>>i was just wondering how www.yahoo.com gives 7-8 IP addresses on a
>>nslookup query? This does mean that they have some sort of load
>>balancing implemented. If a query for www.yahoo.com is from asia it
>>goes to another server, if from europe it goes to another....
>>
> As you'll notice, www.yahoo.com is actually just an alias for
> www.yahoo.akadns.net, i.e. Akamai, which does all of this fancy
> "geographic" load-balancing, using their proprietary, patented
> technology, yadda yadda yadda. Note that the actual load-balancing
> happens behinds the scenes, and the fact that the answer to
> www.yahoo.com has several A records in it doesn't *in*and*of*itself*
> imply that any fancy load-balancing is going on. Anybody can have
> multiple A records associated with a DNS name, and just let it
> randomize, or, for a relatively crude form of load-balancing, could use
> BIND's "sortlist" mechanism to try and split up the load based on the
> source-address ranges of the clients.
>
>>How do they do this? I have a website hosted and i want to do
>>something of the same sort. For a start i want to set up my server to
>>give services from 2 subnets....i mean to say that i have radio
>>connectivity with 2 ISPs. At the moment i have a primary LINK and a
>>backup link. what i want to do is utilize both the links at the same
>>time and create a load balancing scenario. I hope i am making my point
>>clear. I want to set up two LAN cards with differnt IP addresses from
>>the 2 ISPs and then somehow create the situation where both are active
>>at both times.
>>
>>What do i do? Plz guide...
>>
> From a DNS perspective, you could have multiple A-records associated
> with your site's name, as previously mentioned, with or without
> sortlists. Or you could pay a significant amount of money to put
> together a *true* load-balancing solution.
>
>
>                                    - Kevin
>
>
>
> 


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