Default Configuration For Dhcp Snooping - Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual

Chapter 34 Configuring DHCP Snooping
This is a sample bindings file:
3ebe1518
TYPE DHCP-SNOOPING
VERSION 1
BEGIN
1.1.1.1 512 0001.0001.0005 3EBE2881 Gi1/1
1.1.1.1 512 0001.0001.0002 3EBE2881 Gi1/1
1.1.1.1 1536 0001.0001.0004 3EBE2881 Gi1/1
1.1.1.1 1024 0001.0001.0003 3EBE2881 Gi1/1
1.1.1.1 1 0001.0001.0001 3EBE2881 Gi1/1
END
Each entry holds an IP address, VLAN, MAC address, lease time (in hex), and the interface associated
with a binding. At the end of each entry is a checksum that is based on all the bytes from the start of the
file through all the bytes associated with the entry. Each entry consists of 72 bytes of data, followed by
a space, followed by a checksum.
Upon bootup, when the calculated checksum equals the stored checksum, the switch reads entries from
the file and adds the bindings to the DHCP snooping database. If the calculated checksum does not equal
the stored checksum, the entry read from the file is ignored and so are all the entries following the failed
entry. The switch also ignores all those entries from the file whose lease time has expired. (This is
possible because the lease time might indicate an expired time.) An entry from the file is also ignored if
the interface referred to in the entry no longer exists on the system, or if it is a router port or a DHCP
snooping-trusted interface.
When the switch learns of new bindings or when it loses some bindings, the switch writes the modified
set of entries from the snooping database to the file. The writes are performed with a configurable delay
to batch as many changes as possible before the actual write happens. Associated with each transfer is a
timeout after which a transfer is aborted if it is not completed. These timers are referred to as the write
delay and abort timeout.

Default Configuration for DHCP Snooping

Table 34-1
Table 34-1
Option
DHCP snooping
DHCP snooping information option
DHCP option 82 on untrusted port feature
DHCP snooping limit rate
DHCP snooping trust
DHCP snooping vlan
OL-11439-03
shows all the default configuration values for each DHCP snooping option.
Default Configuration Values for DHCP Snooping
Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY
Default Configuration for DHCP Snooping
e5e1e733
4b3486ec
f0e02872
ac41adf9
34b3273e
Default Value/State
Disabled
Enabled
Disabled
None
Untrusted
Disabled
34-5