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Hello. I am trying out my first CMTS solution. So my error may be trivial. I work with normal ethernet. All about CMTS and docsis and special dhcp configuration is new to me.
It is a Teleste DAH100 mini CMTS and the router is pfsense.
What happens
- Modems get to send the DHCP discover package.
- The router responds with the offer.
- Then no more happens, the modems (and a piece of test equipment) does not get an IP and I register no dchp request or ack. Every aprox. 10 seconds it all repeats. The router keeps sending a DCHP offer of the same IP. So it seems right from the router.
Setup:
- There is no VLAN restrictions.
- Switch in CMTS is a layer2 and other equipment using the ethernet ports can get IP from DHCP
- There is no firewall restrictions or blocked packages
Questions:
- is if there is an obvious place to look for this error?
- could it because the DCHP offer does not meet minimum requirements of the CM?
- what are the minimum requrements for a DOCSIS 3.0 CM?
I have attached a DHCP offer after I got my computer (not CM) to create a DHCP discovery. I read a couple of other post in this forum related to same issue.
Thanks
next-server option
Are you using built-in DHCP server (DAH has one) or external? When using an external DHCP server be sure that built-in one is disabled...
It is solved.
Aparently it is not the right way to add tftp-server and filename as option 66 and 67 to the DHCP Offer. It has to be given as "siaddr" and "file" before listing any options.
After doing that change it worked. Very nice to be able to proceed with testion :-) Thanks again for your feedback.
This is from Cisco documentation for some other cable modem:
· An IP address (The yiaddr field in the DHCP packet header)
· A subnet mask (DHCP Option 1)
· The local time offset from GMT in seconds (DHCP Option 2)
· A default router (DHCP Option 3)
· The IP address of a ToD server (DHCP Option 4)
· The log server (DHCP option 7)
· The IP address of a TFTP server (The siaddr field in the DHCP packet header)
· The name of a DOCSIS configuration file (The file field in the DHCP packet header)
· A DHCP lease time in seconds (DHCP Option 51)
In our lab we have Arris C3 CMTS and Motorola SVG1501 modems. I am using ISC DHCP server for provisioning. The DHCP server receives the Discover package and responds with DHCP offer. However the CMTS logs don't show any DHCP offer messages. CMTS and DHCP server are on the same VLAN, they can ping each other successfully.
Can you please post the DHCP config file that worked for you?