question about DHCP HSRP SNOOPING

[luo_40201]

                  

The topology as above:

      Wireless users can get IP address (10.10.1.0/24) from R1 and wired users get it (10.10.2.0/24) from R2.

Now I enable dhcp snooping on the two routers .G3/3 of two routers are set by trust port . G1/4 and G 1/3 of two routers are set by untrust port

Then

1.wired users also get IP address from R2,but wireless users get it from the R1 and R2 .(more IP from  the R2, few IP from the R1)

2.Snooping binding table of wired users is on the R2,not on the R1.

   But snooping binding table of wireless users is on the R1,not on the R2 though users get more IP from the R2 .

so I have some doubt:

1.Why occurs wireless users get IP address from the R2 after  I enable dhcp snooping feature.

2.Even if wireless users get IP from the R2, there is no snooping binding table on the R2, is on the R1?

thanks a lot

[devils_advocate]

Can you post the configs?

Gi1/3 and Gi1/4 should be trusted for DHCP snooping as they are essentially uplinks.

Are you enabling snooping for both Wired and Wireless Vlans?

[luo_40201]

Gi1/3 and Gi1/4 must be untrust otherwise there are  no snooping tables on each routers.

Are you enabling snooping for both Wired and Wireless Vlans? yes!  SW1 didn't enable snooping.

[luo_40201]

Could anyone else solve the problem?

Thanks!

[Lei Tian]

Hi Mars,

Do packet capture on your wireless PC before and after you config snooping, see if there is any difference on the DHCP offer message. Also, post your router configs.


HTH,
Lei Tian

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