NEC IP8800/S6700 Dhcp server communication trouble, Checking filtering/QoS setting information

3.Troubleshooting Functional Failures in Operation

2.Execute the show ip route command to check the route information acquired by this system.

3.Go to "3.7 IPv4 Unicast Routing Communication Failure" if the route information on the failed interface is missing in the route information acquired by this system or if the next hop address is invalid.

4.If the route information acquired by this system contains the route information on the failed interface, the following functions set for the interface may have problem. Check these functions.

•Filtering/QoS function

Go to "(f)Checking filtering/QoS setting information."

•DHCP/BOOTP function

Go to "(g)Checking DHCP/BOOTP setting information."

(f)Checking filtering/QoS setting information

It may have been set to discard only certain packets by filtering, or packets may have been discarded through bandwidth monitoring, discarding control, or shaper of the QoS control.

Check to see if the conditions of filtering and QoS control in the configuration have been set up correctly and if bandwidth monitoring, discarding control, or shaper has been set up appropriately for system operation. For the procedure, see "3.23.1 Checking Filtering/QoS Setting Information."

(g) Checking DHCP/BOOTP setting information

If there are sufficient lease IP addresses remaining in the DHCP/BOOTP server, IP addresses may not be assigned to clients due to configuration setting errors for the DHCP/BOOTP relay. The followings are the steps to check the configuration:

1.Confirm that the IP address of the DHCP/BOOTP server or that of a neighboring router with the DHCP/BOOTP relay agent function has been assigned for ip helper-address.

2.Confirm that ip helper-addresshas been assigned for the client interface.

3.Confirm that ip bootp-hopsis set to a correct "bootp hops" value for the client.

4.For multi-homed configuration, confirm that the "ip relay-agent-address" value matches the IP address subnet distributed by the DHCP/BOOTP server.

(h) Checking when the DCCP relay and VRRP are operated on the same interface

If the DHCP/BOOTP relay and VRRP are operated on the same interface, the DHCP/BOOTP client gateway address (router option) must be set to the virtual router address specified in the VRRP configuration on the DHCP/BOOTP server. Otherwise, communication of the DHCP/BOOTP client may be disabled after master/standby router switching by VRRP. Follow the checking method for each DHCP/BOOTP server.

(2) DHCP server communication trouble

The following are three possible causes for DHCP server communication failures (address not distributed to clients).

1.Configuration error

2.Network configuration has changed

3.DHCP server failure

First, check 1 above. This section describes configurations that are easily misconfigured. For 2 above, check for the differences in the network configuration provided before and after the change. Check for any difference disabling communication. If the configuration and network configuration are correct but IP communications are unavailable because IP addresses cannot be assigned to clients, described in 3 above, see "(b)Checking the log message and interface" through "(e)Checking filtering/QoS setting information" for details.

To locate the failed part and cause, follow the flow below.

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