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MS NLB cause slowness to IIS access

Posted on 2013-01-08
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Last Modified: 2013-01-14
We have 6 web servers running IIS on Win 2003 Enterprise.
We have one NLB VIP configured to load balance among these
6 web servers.

Today, for some reason, users complain for 7 over hours of slowness
till we configure users' PCs to directly access the web servers' actual
IP addresses (we try to group users for each of the 6 web servers).

My Wintel sysadmins says the NLB GUI showed the number of users
http connections are quite evenly distributed during that 7 hours of
slowness.

Now, even with 1 single user pointing to this NLB VIP, it's still slow
while all the rest of the organization's users are Ok (as they're
now directly accessing the actual IP of each web servers).

Any logs to check & how to troubleshoot this further?

Could it be the Cisco switch's issue & what to check on the
switch?  There's no hardware load balancer used.


CPU, RAM utilizations on all web servers are well below 30%
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Question by:sunhux
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7 Comments
 

Author Comment

by:sunhux
ID: 38757962
There no teaming on the web servers' NIC  : we never set this up as we
heard NLB & Teaming together is not supported by MS
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Author Comment

by:sunhux
ID: 38760193
Anything to check on the Layer 2 switches which these servers are
connected to?
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LVL 118

Assisted Solution

by:Andrew Hancock (VMware vExpert / EE MVE)
Andrew Hancock (VMware vExpert / EE MVE) earned 30 total points
ID: 38760553
multicast or unicast?
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Accepted Solution

by:
paulmacd earned 470 total points
ID: 38760554
Do all the IIS servers serve all web sites?

Is the cluster in unicast or multicast mode?

Is there just one VIP?

Are there rules controlling protocols, filters, priority, etc?

Looking at the VIP interface on all the web servers, is any one server actually handling more traffic (look at Sent/Recieved for each NIC)?
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Author Comment

by:sunhux
ID: 38761795
It's unicast.

Yes, just one VIP for all the 6 IIS.

I heard all filters, priority are default during setup; no rules.

How do I check the VIP interface on all the webservers?  Using
netstat -e "interface_name" ?
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Assisted Solution

by:paulmacd
paulmacd earned 470 total points
ID: 38763175
You can't see the interface on all the servers at once, but you can look at the status of the NLB NIC on each server to see if the Sent/Received values on each are consistent with each other and that they make sense.
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LVL 33

Expert Comment

by:paulmacd
ID: 38774900
Thanks for the points.  What was the solution?
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