Assigning fixed and dynamic addresses via DHCP based on Option 82 and vendorclass

[Anders Rosendal]

Hi
I have been struggling getting a configuration where IP-leases is based
on option 82 to work.

I have a network with Cisco-switches able to insert option 82
information in the dhcp-packets.
On the switch-ports both computers, and VoIP devices are connected. When
a VoIP device is connected I want a rfc1918 adress to be assigned (I
don't care exactly which in the range, but, when a device that is not a
VoIP-device is connected I want a for the port fixed public IP to be
assigned.
The VoIP-devices are detected based on the Vendor-class.

i have no problem getting either of these configurations to work, but
not at the same time.

This is the configuration used to match on option 82, i.e. I match on
the remote-id and circuit-id, and create a separate class and pool for
each port:

-------------------------------
class "as07-Fa0/1" {
	match if(substring (option agent.remote-id, 2, 4) = "as07" and
binary-to-ascii (10, 8, "", suffix (option agent.circuit-id, 1)) = "3");
}

subnet 1.2.3.0 netmask 255.255.255.0 {
	option routers 1.2.3.1;
	option subnet-mask 255.255.255.0;
	option broadcast-address 1.2.3.255;
	pool {
		range 1.2.3.20;
		allow members of "as07-Fa0/1";
	}
}
-------------------------------

This is the configuration used for detecting VoIP-devices:

class "VOIP_TA2S" {
        match if substring(option vendor-class-identifier, 0, 4) =
"VOIP";
}

subnet 172.31.4.0 netmask 255.255.254.0 {
	option routers                  172.31.4.1;
        option subnet-mask              255.255.254.0;
        option broadcast-address        172.31.5.255;
        default-lease-time 14400;
        max-lease-time 28800;
        min-lease-time 3600;
        pool {
        	allow members of "VOIP_TA2S";
                option tftp-server-name "1.2.3.254";
                option bootfile-name "configfile.dat";
                range 172.31.5.128 172.31.5.252;
        }
}
----------------------------------




I have tried class-configurations like the one below, where I create two
class-statemanets for each port, matching both option 82 and
vendor-class:

class "as07-Fa0/1" {
	match if(substring (option agent.remote-id, 2, 4) = "as07" and
binary-to-ascii (10, 8, "", suffix (option agent.circuit-id, 1)) = "3"
and not substring(option vendor-class-identifier, 0, 4) = "VOIP");
}

class "as07-Fa0/1-VoIP" {
	match if(substring (option agent.remote-id, 2, 4) = "as07" and
binary-to-ascii (10, 8, "", suffix (option agent.circuit-id, 1)) = "3"
and substring(option vendor-class-identifier, 0, 4) = "VOIP");
}

(There may be syntax-errors in the lines above)


Does anyone have any idéas on how this could be done?

I've been reading dhcp-eval, dhcpd.conf, dhcp-options and some
googeling.

Is it possible? Am I looking in the right direction?


Best Regards Anders Rosendal

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