H3C Technologies H3C S5560 Series Switches - Manual (Page 51)

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Specifying a primary subnet and multiple secondary subnets for a DHCP address pool
An address pool with a primary subnet and multiple secondary subnets allows the DHCP server to assign
an IP address in a secondary subnet to a requesting client when no assignable IP address on the primary
subnet is available.
Follow these guidelines when you specify a primary subnet and secondary subnets for a DHCP address
pool:
• You can specify only one primary subnet in each address pool. If you use the network command
multiple times, the most recent configuration takes effect.
• You can specify a maximum of 32 secondary subnets in each address pool.
• IP addresses specified by the forbidden-ip command are not assignable in the current address pool,
but are assignable in other address pools. IP addresses specified by the dhcp server forbidden-ip
command are not assignable in any address pool.
To specify a primary subnet and secondary subnets for a DHCP address pool:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter address pool view. dhcp server ip-pool pool-name N/A
3. Specify the primary subnet.
network network-address
[ mask-length | mask mask ] By default, no primary subnet
is specified.
4. (Optional.) Specify a secondary
subnet.
network network-address
[ mask-length | mask mask ]
secondary
By default, no secondary
subnet is specified.
5. (Optional.) Return to address pool
view.
quit N/A
6. (Optional.) Set the address lease
duration.
expired { day day [ hour hour
[ minute minute [ second second ] ] ]
| unlimited }
The default setting is 1 day.
7. (Optional.) Exclude the specified
IP addresses from dynamic
allocation.
forbidden-ip ip-address&<1-8>
By default, all the IP
addresses in the DHCP
address pool can be
dynamically allocated.
To exclude multiple address
ranges from the address pool,
repeat this step.
8. Return to system view. quit N/A
9. (Optional.) Exclude the specified
IP addresses from dynamic
allocation globally.
dhcp server forbidden-ip
start-ip-address [ end-ip-address ]
Except for the IP address of
the DHCP server interface, IP
addresses in all address pools
are assignable by default.
To exclude multiple address
ranges globally, repeat this
step.