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New Member

switch question: Intel NIC load balancing software

I am using Intel NICs that have the software than enables redundancy and/or load balancing of 2 NICs. So the 2 physical NICs create 1 logical NIC that has the TCP/IP config attatched to it.

This raises all kinds of layer2 questions in my head since there are really two nics with 2 different mac addresses.

Since there are physically 2 cables then from the server to the switch do I need to do anything on the switch end? trunking? (may be wrong term.. I'm new to the more advanced switch configs) something that makes the 2 switch ports act as 1 since the 2 nics are acting as 1?

any help is appreciated. Thanks.

5 REPLIES
New Member

Re: switch question: Intel NIC load balancing software

There will not be any Layer 2 issue i.e. STP loops, intel software will make ONE virtual (logical)adapter of MAC address (any of TWO participating NICs) .

and outside world will be seeing this MAC address i.e. your IP address will always be bind to this virtual MAC address.

To clear your doubt--

Suppose you have two NICs "A" and "B", connected to switchA and switchB.

Now suppose the Vritual MAC address is "A".

In normal condition----

SwtichA mac table will contain --- A

SwitchB mac table will contain --- B

Now if your NIC "A" has gone down ,

SwtichA mac table will contain --- nothing

SwitchB mac table will contain --- A ( here immediately it will remove your old entry ,)

So for outside world that IP address is still reachable.

hope this clears your doubt,

New Member

Re: switch question: Intel NIC load balancing software

Thanks. Getting much clearer. Most importanly you've verified its NOT a problem so I can rule that out while troubleshooting some network slowdowns I'm experiencing. thank you.

Just to understand further though: I assume then if both nics are plugged into the same switch then both switch ports will have the same logical mac address in it's table? (for load balancing config of the intel software) If that is true then does the switch send packets out both ports and hence, load balancing?

thanks again for your response.

New Member

Re: switch question: Intel NIC load balancing software

I have not tested for load balancing.What i have posted in earlier resopnse is for redundancy only i.e. one NIC is Active and other is standby.

What i think is ,by configuring etherchannel ( bundling ports) on switch you can acheive load balancing too.

Bronze

Re: switch question: Intel NIC load balancing software

This is where the switch should be configured with a channel so it sees the two ports as one connection. If you dont then the switch will think the mac address is flapping between the two ports. The host will split the load according to whatever algorythm it is configured with but the switch will only send packets to the host on one port at a time, the last one it saw a packet come from.

I didn't catch what kind of switch it is so I cannot tell you how to configure it now. But when you configure a channel the switch will understand that the mac is on both ports and will distribute the load. Distribution can be based on source and/or destination mac or ip addresses. It hashes that factor to choose a port to use so in this case to get the most variety you would use source IP address. If you used destination mac or IP it woul donly use one port because they are always the same (the host).

It still works as a redundant link. If one port in the channel fails the other continues working.

New Member

Re: switch question: Intel NIC load balancing software

smc6624m tigerswitch. It is a managed switch but I don't know off hand if it supports what you mentioned. I will go through the manual today (with great suspense!)

I should be looking for creating 'channels' . is that correct?

right now I have 20 to 30 people all hitting this server and there seems to be a delay in opening files... Also, For file copy operations etc... once they start they move along fine. Doesn't seem to be a bandwidth issue... I would hope not with only around 30 machines on a fully switched 10/100 lan! Could this delay be a symptom of not having the switch configured with the channel?

Do you know of a 'counter' I should use in windows2k server's 'performance' monitor to check for network issues such as this?

thanks so much for the info.

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