Cisco ubr 10k 3G60 PRE4 with SCH5.
I want so see the upstream description in my dhcp logs. So I added "cable dhcp-insert upstream-description" to the bundle interface.
When I check my logs I see something like this:
...: Agent Circuit ID: 800603fa
...: Agent Circuit ID: 80020407
...: Agent Circuit ID: 800603fa
...: Agent Circuit ID: 800803eb
...: Agent Circuit ID: 80020407
But this is not the description I expect.
The same solution is working with Casa CMTS.
Any idea what could be wrong?
Puhh, I can't see whats wrong.
As far as I know I have to activate the dhcp relay agent (we have an external dhcp server) by cable helper-address in bundle-interface.
And with cable dhcp-insert upstream-description and upstream descriptions in cable-interfaces I should see those descriptions in dhcp discover messages on our dhcp server. But instead there is this strange id.
I think you are looking at the wrong data
Commands like "ip dhcp relay information option" will enable option 82 to be sent from CMTS to DHCP server. The usual options sent will be :
* 82.1 Agent Circuit ID. From memory this is the SNMP interface number of the upstream port the CM is connected to
* 82.2 Agent Remote ID. This is the CM MAC (usefull for providing linkage of CPE to parent CM)
* 82.9(VendorSpecific).4491(CableLabs).1(DOCSIS Version Number): eg "3.0"
I believe the commands "cable dhcp-insert xxxxx" can add extra option 82.9 fields such as:
* 82.9(VendorSpecific).9(Cisco).1(Hostname)
* 82.9(VendorSpecific).9(Cisco).3(Upstream Port Description). Note, not the port name, but the upstream description field.
Probably others too, but I haven't really used these much so don't have a lot of knowledge to share.
When trying to work out some of these more complex DHCP fields, I find it best to capture on the DHCP server (eg tcpdump -w) , and then open the resulting pcap file in wireshark. Wireshark is smart enough to decode most fields, and then any remaining unrecognised vendor specific type fields can easily enough be decoded by hand from their TLV formats.
hello mbowe
you're right, Cisco does it in an other way than Casa.
Casa put the upstream description into 82.1 (Agent Circuit ID) while Cisco does it in a way you described it.
Thank you. I'm a step further