Ran into a problem last week where our vendor’s Cyclades TS100 devices couldn’t acquire an IP address from our Cisco 871 router’s DHCP service.

This was a big problem for us because we have about 70 locations using this router and all of them will have these Cyclades TS100s installed in the next two weeks.

After about two days of troubleshooting/testing and working with the vendor we finally figured out the problem. All we had to do to make it work was enabling spanning-tree portfast on the Cisco 871 ports. What gave it away was when we put a switch in between and the TS100 was able to receive an IP with that set up.

To enable spanning-tree portfast, type in these commands:

en
config t
interface faX
spanning-tree portfast<br>

For more tips on troubleshooting DHCP problems with Cisco devices please see this website:

Troubleshooting DHCP