With DHCP Relay, the switch only participates in forwarding the
requests and replies to and from the client and the DHCP server. The
switch always acts as the relay agent, on which you configure the
forward path to the server.
To troubleshoot DHCP Relay issues on the switch, use the following
procedure.
Procedure
- Verify that the DHCP
server is reachable using ping. If ping is working and the DHCP server
is reachable, DHCP should work.
- Verify that the relay
agents and the forward path configured are reachable. Ping the server
and the gateway to the server.
- Check that the relay
agent configurations are correct. Also verify that DHCP is enabled
on the switch:
show
ipv6 dhcp-relay interface {gigabitEthernet {slot/port[/sub-port][-slot/port[/sub-port]][,...]}|vlan <1-4059>
- Verify that IPv6 forwarding
is enabled globally:
- Verify that the IPv6
based VLAN where the DHCP relay agent is configured is enabled:
show
ipv6 interface vlan <1-4059>
- In a scenario with
VRRP and SMLT, configure VRRP IP as the DHCP relay agent.
- When using the VRRP
VRID as the relay agent, make sure the VRRP configurations are proper.
- To verify that relay
forward and relay receive are working, enable trace for DHCP with
IPv6, and grep trace for relay:
trace
level 66 3
trace
grep relay
trace
screen enable
- Display the count of
DHCP Relay requests and replies to verify the system received requests
and replies:
show
ipv6 dhcp-relay counters
