3Com 10014299 manual Router-dhcp2nbns-list Router-dhcp2gateway-list

344CHAPTER 21: CONFIGURING IP APPLICATION

4Configure the attributes (address pool range, outgoing gateway and address lease period) in DHCP pool 1.

[Router] dhcp server ip-pool 1

[Router-dhcp1]network 10.1.1.0 mask 255.255.255.128

[Router-dhcp1]gateway-list 10.1.1.126

[Router-dhcp1]expired day 10 hour 12

5Configure the attributes (address pool range, outgoing gateway, NetBIOS address, and address lease period) in DHCP pool 2.

[Router] dhcp server ip-pool 2

[Router-dhcp2]network 10.10.1.128 mask 255.255.255.128

[Router-dhcp2] expired day 5

[Router-dhcp2]nbns-list 10.1.1.4

[Router-dhcp2]gateway-list 10.1.1.254

Troubleshooting Fault: Dynamic IP address allocation conflict occurs at the client.

Solution: Following these steps to solve this problem.

1First of all, determine whether there is a host with this IP address on the network. You can perform the ping operation with relative long timeout to check the connectivity of this IP address.

2If a host with this IP address exists, you need to use the command dhcp server forbidden-ipto configure this IP address does not participate in dynamic address allocation.

3At the client, use ipconfig /release_all

dynamically, and use ipconfig /renew_all

command to release the IP address to re-apply dynamic addresses.

Configure DHCP Relay As the scale of networks grows and their complexities increase, network configurations become more and more complex. The original BOOTP protocol for static host configuration cannot satisfy the demands of users, especially on the occasions when computers are always on the move (e.g., using laptops or wireless network) and the number of actual computers exceeds that of the available IP addresses. To facilitate users to improve utilization ratio of resources and to support diskless networking mechanisms, the DHCP (Dynamic Host Configuration Protocol) based on BOOTP was developed. Similar to the BOOTP protocol, DHCP works in client-server mode. With this protocol, a DHCP client can dynamically request configuration information from a DHCP server, including important parameters such as assigned IP addresses, subnet masks and default gateways, etc. DHCP server can also conveniently configure this information dynamically for DHCP clients.

However, original DHCP can only take effect in a sub-net, and cannot work across different network segments, which is obviously not economic. So, it is necessary to set a DHCP server on all network segments for dynamic host configuration. This problem is solved by the introduction of DHCP relay, which relays relative messages to a destination DHCP server, so that multiple networks can share a DHCP server, which is more cost-effective and convenient for centralized management.