DHCPv6 Logging SubOptions and Relay-Agent Options

Philippe Maechler plcmaechler at gmail.com
Wed Jun 29 14:46:05 UTC 2016

Hello List

I’m trying to get the cable modem mac address written to the log file.

The Setup is simple, the CMTS is forwarding the request from the cpe
directly to the dhcpv6 server. So there is only one relay agent involved

Request from the cablemodem or emta gets relayed to a different (ipv4 only)

The following lines in my conf-file just print "(missing)"

log ( info, concat("Interface-ID: ", pick-first-value((v6relay(32, option
dhcp6.interface-id)), "(missing)")));

log ( info, concat("LLA: ", pick-first-value((v6relay(32, option
dhcp6.client-linklayer-address)), "(missing)")));

adaptet from

All the information are there (seen in wireshark ;)). But I’m not sure on
how to get them.

 [image: Inline images 1]

The initial plan is to create classes based on the cm-mac and based on that
give them an address or not.

Furthermore I’d like to get other data from the relay-agent (CMTS) and do
funny stuff with it, like update the firmware if it is too old

Can anybody help me out and give me a hint?


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