Diagnosing DHCP issues with CGE

Document created by mathaker on Sep 18, 2014Last modified by mathaker on Sep 18, 2014
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If your endpoints are not receiving DHCPv6 leases, check the following:

  • The management server is up an running and reachable (using IPv6) from the FAR:
    • From the FAR's console CLI, ping6 the management server at its ipv6 address
  • If you are using a FAR FW revision prior to CG5(68), Make sure that the "rpl prefix" details in the WPAN config in the FAR match the IPv6 address of the WPAN interface.  Otherwise the "rpl prefix" setting is unnecessary.
  • Make sure that the endpoints are link-neighbors of the FAR
    • At the FAR console CLI type "show wpan linknbrs table".  All of the endpoint CMs should appear.  Here is an example: How to See the WPAN Neighbor Table
    • If they don't, make sure that the endpoints' programmed in "SSID" matches the SSID configured in the FAR's WPAN interface
  • Enable dhcp request tracing in the FAR using the "debug" command.  Type "debug dhcpv6-relay dhcpv6_ra_default terminal" or "debug dhcpv6-relay dhcpv6_ra_default trace"
  • Power cycle the endpoints and look for DHCP requests from them within 10 -15 mins.
    • Look for requests from the endpoints followed by replies from the server
    • If the dhcp server is not responding to these requests, stop and restart the dhcp server (on the mamangement server's Linux guest VM) in debug mode (see above) and look for the requests followed by any error messgaes.
  • You may also monitor all WPAN traffic using the procedure outlined here: Capturing WPAN traffic
  • If you see" ICMP unreachable" packets right after "dhcp solicit" message with step above, please make sure your wpan module is in slot4 for FAR running CG-OS image and slot3 for FAR running IOx image
  • By default, the endpoints will make DHCP requests with a frequency that decreases over time.  For debugging purposes you may wish to make the requests more frequently.  Use the endpoint's config file (see CGE Configuration Writer) to adjust the parameters "Dhcpv6_Cfg.Dhcpv6SolicitIntervalMax" and "Dhcpv6_Cfg.Dhcpv6SolicitIntervalMin".  Setting them both to 60 seconds will generate a DHCP request approximately once per minute.

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