01-20-2014 08:03 PM - edited 03-07-2019 05:41 PM
Hi
We have enabled dhcp snooping for all vlan configured on the switch, but only few vlan show up as operational. Please clarify.
Cisco IOS Software, Catalyst 4500 L3 Switch Software (cat4500e-IPBASEK9-M), Version 12.2(53)SG8, RELEASE
ip dhcp snooping vlan 30,100-119,300-349,400-449,600,700,710,996-997
Switch#sh ip dhcp snooping
Switch DHCP snooping is enabled
DHCP snooping is configured on following VLANs:
30,100-119,300-349,400-449,600,700,710,996-997
DHCP snooping is operational on following VLANs:
30,108,308,600,700,710,996-997
DHCP snooping is configured on the following L3 Interfaces:
Insertion of option 82 is disabled
circuit-id default format: vlan-mod-port
remote-id: 0026.9914.8a80 (MAC)
Option 82 on untrusted port is not allowed
Verification of hwaddr field is enabled
Verification of giaddr field is enabled
DHCP snooping trust/rate is configured on the following Interfaces:
Interface Trusted Allow option Rate limit (pps)
----------------------- ------- ------------ ----------------
TenGigabitEthernet5/1 yes yes unlimited
Custom circuit-ids:
TenGigabitEthernet5/2 yes yes unlimited
Custom circuit-ids:
Port-channel1 yes yes unlimited
Custom circuit-ids:
01-20-2014 09:08 PM
Is there an active port on that switch for the non-operational snooping Vlans?
Sent from Cisco Technical Support iPad App
01-21-2014 06:56 AM
Initially I thought the same as Jeff in that you needed ports in the Vlans before they became operational for DHCP snooping but a quick test on a 3750x I have here disproved that.
The only way I could replicate your scenario was to enable DHCP snooping for non existant Vlans.
For example, enabling DHCP snooping for Vlans 10-20 would show:
Switch#sh ip dhcp snooping
Switch DHCP snooping is enabled
DHCP snooping is configured on following VLANs:
10-20
DHCP snooping is operational on following VLANs:
10-20
But ONLY if Vlans 10-20 existed as L2 vlans.
If I deleted Vlan 19, I see the following:
Switch#sh ip dhcp snooping
Switch DHCP snooping is enabled
DHCP snooping is configured on following VLANs:
10-20
DHCP snooping is operational on following VLANs:
10-18,20
I suspect you have enabled DHCP snooping for L2 Vlans which do not actually exist in the Vlan database on that switch??
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