Cisco: limit number of DHCP addresses per VC?

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1

Question for the list:

Cisco introduced a command in 12.3T to limit DHCP leases on ATM unnumbered interfaces (ip dhcp limit lease per interface). This feature works fine on our 7206VXR, but my problem is that this is a global command. The Redback we were using before had us spoiled by allowing us to specify max DHCP leases per ATM VC! We would like to put other ATM VC’s on this router that have different DHCP lease requirements.

Is there any way of limiting DHCP leases per VC? Cisco TAC said they didn’t have a non-global version of the ip dhcp limit lease per interface command.

Our DHCP server is running dhcpd 2.0p15, BTW.

Thanks,

= TC

2

Question for the list:

Cisco introduced a command in 12.3T to limit DHCP leases on ATM unnumbered
interfaces (ip dhcp limit lease per interface). This feature works fine on
our 7206VXR, but my problem is that this is a global command. The Redback we
were using before had us spoiled by allowing us to specify max DHCP leases
per ATM VC! We would like to put other ATM VC's on this router that have
different DHCP lease requirements.

Is there any way of limiting DHCP leases per VC? Cisco TAC said they didn't
have a non-global version of the ip dhcp limit lease per interface command.

Our DHCP server is running dhcpd 2.0p15, BTW.

You can use the option 82 in the DHCP packet to do this on the DHCP
server, something like

# By default limit all customers to 1 DHCP lease
class "customer" {
  spawn with option agent.remote-id;
  lease limit 1;
}

subclass "customer" __OPTION_82_STRING_FOR_CUSTOMER__ {
  lease limit 2;
}

__OPTION_82_STRING_FOR_CUSTOMER__ will be something like

01:01:00:00:01:02:03:04:40:02:01:20
^^^^^^^^^^^ ^^^^^^^^^^^ ^^ ^^ ^^^^^
  fixed NAS IP addr | | VCI
                        > VPI
                  Port in this case 4/0

So this customer's pvc is 2/288 on ATM4/0 on the NAS with address
1.2.3.4

/Jesper