NLB Windows 2003 - flood switch

Suporte CCE
Suporte CCE used Ask the Experts™
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Im trying to avoid flood switch in order to use NLB with 2 webservers(just one configured on NLB during the tests).

Even with a layer3 switch, with IGMP enabled, Im having flood.

- 1 webserver(win2003 SP2) on a layer3 switch
- the layer3 switch(3COM 3300) with a cable to another switch on our network
- multicast with IGMP enabled
- the VMAC added on the switch to the webserver port(the mac is automatically added if I turn on the IGMP learning)

I just hit F5 on browser and al lights on both switches starts to blink.

I tried 2NICs with unicast with the NIC wheres the LNB configured with a different subnet, still flood.

I read somewhere else to use a HUB, but I dont have one available.

What´s the correct thing to to here?
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Commented:
Are all lights blinking or just the two web servers?  NLB should hit all member servers if using IGMP multicast, you may need static MAC table entries to make it work right.  Without multicast, all ports on the broadcast domain should light up which is where you start having issues.  
If you can't get it working right can you just carve out a VLAN an isolate the two servers?
Suporte CCESystem Administrator

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Commented:
All lights blinking.

Using Multicast, IGMP enabled on both NLB and switch.

The port has 2 MACs configured on the switch, one from the NIC and the other one from NLB. Still flooding.

How should I do that with VLAN? If I create a 2nd VLAN,  and add the port, I loose communication with that port, how the site becomes available on that situation?

Commented:
You have a Layer 3 switch so if you carve out a VLAN you can route from network to network.  You create a router on a stick with a new gateway for the VLAN; that would totally isolate the broadcasts to the new VLAN only.  I know NLB can be done without a major impact on the switches.  
Suporte CCESystem Administrator

Author

Commented:
We resolved the issue using a dumb hub. Please close the topic.
Commented:
I would keep testing this if you have a busy site; hubs are really bad devices compared to switches.  They are prone to collissions, they are not (to my knowledge) full duplex, and (to my knowledge) don't come in gigabit.  Your site probably doesn't need GB but how about backups?  The best solution in my opinion is using a hardware load balancer with a gigabit network.  You are going backwards in quality from: gigabit with a hardware load balancer, to gigabit with IGMP NLB, to NLB with a hub.  
If you do stay with this solution you should really be on the lookout for packet issues since simple CSMACD isn't a perfect solution...that is why switches were made!  

BTW, no points for the advice?  

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