Reference Guide
336 | Dynamic Host Configuration Protocol (DHCP)
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Figure 14-6. Command example: show ip dhcp snooping
Dropping DHCP packets on snooped VLANs only
Binding table entries are deleted when a lease expires or the relay agent encounters a DHCPRELEASE.
When the binding table fills, DHCP packets are dropped only on snooped VLANs, while such packets will
be forwarded across non-snooped VLANs. Since DHCP packets are dropped, no new IP address
assignments are made. However, DHCP Release and Decline packets are allowed so that the DHCP
snooping table can decrease in size. Once the table usage falls below the max limit of 4000 entries, new IP
address assignments are allowed.
View the number of entries in the table with the
show ip dhcp snooping binding command. This output
displays the snooping binding table created using the ACK packets from the trusted port.
Figure 14-7. Command example: show ip dhcp snooping binding
Dell#show ip dhcp snooping
IP DHCP Snooping : Enabled.
IP DHCP Snooping Mac Verification : Disabled.
IP DHCP Relay Information-option : Disabled.
IP DHCP Relay Trust Downstream : Disabled.
Database write-delay (In minutes) : 0
DHCP packets information
Relay Information-option packets : 0
Relay Trust downstream packets : 0
Snooping packets : 0
Packets received on snooping disabled L3 Ports : 0
Snooping packets processed on L2 vlans : 142
DHCP Binding File Details
Invalid File : 0
Invalid Binding Entry : 0
Binding Entry lease expired : 0
List of Trust Ports :Te 0/49
List of DHCP Snooping Enabled Vlans :Vl 10
List of DAI Trust ports :Te 0/49
Dell#show ip dhcp snooping binding
Codes : S - Static D - Dynamic
IP Address MAC Address Expires(Sec) Type VLAN Interface
========================================================================
10.1.1.251 00:00:4d:57:f2:50 172800 D Vl 10 Te 0/2
10.1.1.252 00:00:4d:57:e6:f6 172800 D Vl 10 Te 0/1
10.1.1.253 00:00:4d:57:f8:e8 172740 D Vl 10 Te 0/3
10.1.1.254 00:00:4d:69:e8:f2 172740 D Vl 10 Te 0/50
Total number of Entries in the table : 4