ISC.ORG DHCP Server Option 82 - Use Circuit ID to assign fixed IP address

[Ryan Zierden]

ISC.ORG Community:

 

I have all the DHCP option data coming from my DSLAM up through up to my
DHCP server as seen below.

 

Example of dhcpd.log show dhcp option 82 data:


Apr 25 13:57:08 inetdhcp dhcpd: DHCPDISCOVER from 00:90:d0:25:46:a4 via
172.21.61.1 
Apr 25 13:57:08 inetdhcp dhcpd: DHCPOFFER on 172.21.61.10 to
00:90:d0:25:46:a4 via 172.21.61.1 
Apr 25 13:57:08 inetdhcp dhcpd: Lease for 172.21.61.10 is connected to ADSL
Port 1, on VPI/VCI 0/35, VLAN 310 on Switch 172.16.105.2 
Apr 25 13:57:08 inetdhcp dhcpd: DHCPREQUEST for 172.21.61.10
(192.168.250.200) from 00:90:d0:25:46:a4 via 172.21.61.1 
Apr 25 13:57:08 inetdhcp dhcpd: DHCPACK on 172.21.61.10 to 00:90:d0:25:46:a4
via 172.21.61.1

 

Got this simply by turning on "dhcpr enable" in theDSLAM and then on the
VLAN interfaces on the Cisco 7609-S configuring "ip dhcp relay information
trusted" and adding the following config to the global section of my
dhcpd.conf file:

 

if exists agent.circuit-id 
{ 
log (info, concat("Lease for ", binary-to-ascii (10, 8, ".",
leased-address), " is connected to ADSL Port ", 
binary-to-ascii (10, 8, "", substring(option agent.circuit-id, 0, 1)), ", on
VPI/VCI ", 
binary-to-ascii (10, 16, "/", substring(option agent.circuit-id, 1, 4)), ",
VLAN ", 
binary-to-ascii (10, 32, "", substring(option agent.circuit-id, 5, 4)), " on
Switch ", 
binary-to-ascii (10, 8, ".", substring(option agent.circuit-id, 9, 4)))); 
}

 

My Question is:

How do configure ISC.ORG dhcpd.conf file to assign fixed-address based on
the circuit ID information as opposed to the MAC-ID.

 

We have been doing the following which works but is cumbersum as CPE MAC ID
change frequently:

# TEST PORT 1 
host rgn-172-21-61-10 { 
hardware ethernet 00:90:d0:25:46:a4; 
fixed-address 172.21.61.10; 
} 

And want I want to do is something like this (note this is not the correct
syntax to configure this properly this but gives you the logic of what I am
after:


To something like 
# TEST PORT 1 
host rgn-172-21-61-10 { 
agent.circuitID ADSL Port 1, on VPI/VCI 0/35, VLAN 310 on Switch
172.16.105.2; 
fixed-address 172.21.61.10; 
}

 

 

Does anyone have ISC.ORG DHCP configured properly where it is working to
assign fixed IP address based on circuit id information from option 82? If
so, I would be very interested in hearing from your as to how you properly
configure this scenario. Most of my research so far indicates I have to have
ISC.ORG 3.x (which I do) and use client class and subclass but I cannot find
working examples of this nor do I know if it is the correct direction to
pursue or not. 

 

I thank you in advance for any assistance you may be able to offer me.

 

Thank you,

 

Ryan Zierden

IT Manager

diversiCOM - MTC

 

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