The versions of the two NE40Es are V300R002C06B21B. NE40E-1 and NE40E-2 serve as the DHCP server and the DHCP relay respectively. NE40E-2 uses the same sub-interface to terminate multiple VLAN accesses. After the configuration, the address is inaccessible through the testing PC.
1. The testing PC randomly chooses an address in the address pool and configures it as static. If the static address and the interface gateway address of NE40E-2 (DHCP relay) can ping each other successfully, the fault does not occur on the Layer 2 network. After the testing PC captures packets with ethereal, the PC can send the dhcp discover packet normally, but fails to receive the dhcp offer packet.
2. On NE40E-2 (DHCP relay), the interface address and the relayed address can ping each other successfully.
3. Debug the DHCP packets on NE40E-2 (DHCP relay) and NE40E-1 (DHCP server). The packet is sent to the testing PC.
4. Continue to analyze the dhcp offer packet sent by NE40E-2. When terminating multiple VLAN data at the same sub-interface, NE40E only carries the first VLAN tag, one of which configured continuously. Therefore the dhcp offer packet cannot find the VLAN corresponding to the testing PC, and thus is discarded on the switch.
5. On the switch, add the interface connected to the testing PC to the first VLAN configured with terminate continuous VLAN on the NE40E, the testing PC can access the address.
1. The Layer 2 network of the testing PC is disconnected. The dhcp discover packet cannot be sent out or the packet fails to arrive at the DHCP Server.
2. The address of NE40E-2 (DHCP relay) and that of NE40E-1 (DHCP server) cannot be pinged.
3. NE40E-1(DHCP server) does not send the dhcp offer packet, or the device between NE40E-2 (DHCP relay) and NE40E-1(DHCP server) discards the packet.