3Com 3036, Configuration Manual

Page: 348 / 762

344 C
HAPTER
21: C
ONFIGURING
IP A
PPLICATION
4 Configure 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
5 Configure 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.
1 First 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.
2 If a host with this IP address exists, you need to use the command
dhcp server
forbidden-ip
to configure this IP address does not participate in dynamic address
allocation.
3 At the client, use
ipconfig /release_all
command to release the IP address
dynamically, and use
ipconfig /renew_all
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.