load balancing 2 ISPs

dualblade

Supreme [H]ardness
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Nov 19, 2000
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background: at my office, we're getting a second isp for backup in case our primary goes down. we have 3 sites, and a vpn link runs between them. without internet access, the office is practically helpless. our primary connection can handle more users, but the secondary one actually has a higher (much higher) transfer speed. i'm thinking that as long as we're paying monthly for this second service, it might as well be put to use all the time. it's a business cable connection (15/2) that has a fixed monthly charge, so full time usage doesn't cost any extra. our network architecture is made up of several win2k3 servers in one domain across the 3 locations.

task: in order to make use of this secondary net service, i'd like to install a second network card in the server and balance the load between the 2 ISPs. does server2k3 have the ability to detect and accurately balance load between two connections or does this require 3rd party software?

thanks very much for the advice
 

XOR != OR

[H]F Junkie
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I would take all non-critical traffic and drop it on the second ISP. Only critical traffic would get out on the primary line.

Anything more than that, I'm not sure it's worth the time and trouble.
 

SJConsultant

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Server 2003 cannot natively load balance internet connections. You would be much better off using 2 Dual WAN VPN routers that feature load balancing w/ VPN failover.
 

dualblade

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XOR != OR said:
I would take all non-critical traffic and drop it on the second ISP. Only critical traffic would get out on the primary line.

Anything more than that, I'm not sure it's worth the time and trouble.

i could do this, but i'm not really sure it'll help things much. the web traffic is very little compared to our vpn traffic, so although this will make the web faster, i'm not sure how much of an improvement it'll provide. i was hoping, if not actual load balancing, to use some sort of channel bonding to take advantage of both ISPs. i know that there is a registry key that makes windows aware of using multiple nics for outgoing traffic, but i wasn't sure if this provided any load balancing, or if it's even necessary
 

XOR != OR

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dualblade said:
i could do this, but i'm not really sure it'll help things much. the web traffic is very little compared to our vpn traffic, so although this will make the web faster, i'm not sure how much of an improvement it'll provide. i was hoping, if not actual load balancing, to use some sort of channel bonding to take advantage of both ISPs. i know that there is a registry key that makes windows aware of using multiple nics for outgoing traffic, but i wasn't sure if this provided any load balancing, or if it's even necessary
Well, depending on the app, what you could do is establish a second VPN, and do ghetto load balancing with DNS. Single A record pointing to two different IPs.

With two different ISPs, however, there isn't much you can do.
 

dualblade

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what would happen if i enabled the setting in the registry to use both nics' outbound connections? how would windows choose which nic the request went out on?

btw, if you dont' know what registry key i'm talking about, i can link you
 

MrGuvernment

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it would use the nic that has priority 0 by default, if you check your advance NIC settings you can set which NIC has priority.
 

mjz_5

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i have a linksys business dual WAN VPN router, its sucks.. Load balacing makes everything slower, even with different files being downloaded on different computers. and fail mode takes forever to detect that the primary internet went down and to switch to the backup
 

dualblade

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MrGuvernment said:
it would use the nic that has priority 0 by default, if you check your advance NIC settings you can set which NIC has priority.

what would cause it to switch over to nic 1? does it meter link usage? is there a way to set the switchover point?
 
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