DHCP Snooping Issue

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Mar 12th, 2009
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Dear All,

Has any one seen the following DHCP issue with DHCP snooping.

Once we enable DHCP snooping the clients are unable to get IP address from the server we are using PIX 515 firewall as a Relay agent.

The moment we disable option 82 the clients are getting IP address but if we do release / renew then again the client is unable to fetch the IP from Server.

The same is working when we use L3 switch as a relay agent.



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dzanolari Fri, 03/13/2009 - 01:38
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Assuming "dhcp snooping trust" has been set on the links connecting to the DHCP server, check as well IOS release notes. I stumbled over a DHCP snooping bug affecting the 6500 series when using VRF light.

Check as well logs and do a debugging on the switches:

debug ip dhcp snooping event

debug ip dhcp snooping packet

jamaludeen_s Wed, 03/18/2009 - 22:15
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Our Network topology consists of Access, Distribution and Core switch...

DHCP request from the client should go through these switches to get IP from DHCP server.

We tried debugging ip dhcp snooping packet and found that the packets are not coming to core switch, then we directly connected laptop to core switch but client fails to get IP address and no DHCP snooping packets are coming to Core switch...

Finally we Recreated VLAN 10 (by deleting and configuring on Core switch) and it started working….




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