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Unicast flooding - Need help - maybe static mac assign

Posted on 2006-11-06
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Last Modified: 2013-11-13
Here’s the situation

We have a Spectralink 802.11b wireless phone system that is causing problems. The phone system consists of 11 gateways (devices) that plug into a Cisco 2950 switch. The Spectralink system needs to be on the same VLAN as the wireless system, which is throughout the entire hospital. The wireless VLAN is on every trunk in the hospital.

The problem is that, every now and again, our network is flooded with unicast packet from the one Gateway (source) to the master gateway (destination). The source device is usually never the same, but the destination always is, which is the master device that controls the whole system.

I think the problem is with the MAC table on the switch get overloaded and drops all mac’s and does not learn the master device again. The switch receives a packet from gatway #9 destined for Gateway #1 , but cannot find it. It floods all ports on the wireless VLAN with unicast packets, but never learns it. I use Ethereal and can capture 160000 packets in less than 1 second.

Can I statically assign a MAC address to a port so all traffic destined for that MAC must go to that port even if the gateway craps out? I want to statically assign the 11 gateways to their specific ports so I can at least stop the flooding. I need to know if this can be done and how do I do this? Is this the same as port security command and sticky command?

Thanks
J
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Question by:jasonlkennedy
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4 Comments
 
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Expert Comment

by:pseudocyber
ID: 17880472
This command will assign the mac to vlan to and interface fa 1/0/1.

:mac address-table static f00d.beef.f00d vlan 10 int fa 1/0/1

You might try playing around with your aging timers - make things age out of the MAC table faster.  Sounds like you need some consulting to come in and take a look at your lan - especially if you're doing wireless voice.
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by:jasonlkennedy
ID: 17880709
Will this command make the mac address stay in the table even if the switch is rebooted?
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Accepted Solution

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jasonr0025 earned 500 total points
ID: 17880990
after you're done adding above commands add
copy run start
This will preserve settings after reboot
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Author Comment

by:jasonlkennedy
ID: 17929529
oops, i meant to accept pseudocyber's answer. any way to change it?
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