3Com Router User Manual

DHCP Server Configuration337
■Configure the range of a DHCP address pool
■Configure the IP addresses that do not participate in auto-allocation in the 
DHCP address pool
■Configure the lease valid period of the IP addresses in a DHCP address pool
■Configure the IP address of the outgoing gateway router at the DHCP client
■Configure the domain name of the DHCP client
■Configure the IP address of the DNS server used by the DHCP client
■Configure the IP address of the NetBIOS server used by the DHCP client...

338CHAPTER 21: CONFIGURING IP APPLICATION
By default, no DHCP address pool is created.
3Configure the range of a DHCP address pool
aConfigure the static binding address allocated to the client
Some special clients (e.g., WWW server) need to be bound with fixed IP addresses, 
that is, to bind a certain client MAC address with a certain IP address. When the 
client with this MAC address applies for a DHCP address, the server will find the 
corresponding fixed IP address according to the client MAC address,...

DHCP Server Configuration339
The command network cannot be superimposed, that is, the latest configuration 
will overwrite the previous one.
The command network and the commands static-bind ip-address and 
static-bind mac-address are conflicting. In other words, for the same DHCP 
address pool, configure either dynamically binding address or the dynamic 
address, but not both.
4Configure the IP Addresses in the DHCP Address Pool not participating in 
Auto-allocation
As for a network or subnetwork, some...

340CHAPTER 21: CONFIGURING IP APPLICATION
By default, the valid leasing period of IP address is 1 day.
6Configure the IP Address of Egress Gateway Router for DHCP Clients
When a DHCP client accesses a server (or host) beyond the local subnetwork, all 
the data must be sent and received via the egress gateway for the local network. 
Only a maximum of 8 egress gateway addresses can be configured in each DHCP 
address pool.
Perform the following configurations in DHCP address pool view.
Ta b l e 372...

DHCP Server Configuration341
That is because the new DNS address will replace the previous one rather than 
superimpose it.
9Configure IP Address of NetBIOS Server Used by DHCP Clients
Clients can communicate through the NetBIOS protocol. As for the clients installed 
with the Microsoft operating system, WINS (Windows Internet Naming Service) 
Server will provide the hostname-to-IP-address resolution mechanism for the hosts 
adopting the NetBIOS protocol. Therefore, WINS setting is necessary for most...

342CHAPTER 21: CONFIGURING IP APPLICATION
assume that the IP address in this segment is not in use. Only when it is not in use 
can the IP address be allocated to the specified client.
Perform the following configurations in system view.
Ta b l e 377   Configure maximum number of ping packets sent by DHCP server & time for 
response
By default, the number of ping packets being sent is 2 and the time waiting for 
ping response packets is 500ms.
12Configure self-defined options
As DHCP continuously...

DHCP Server Configuration343
Typical DHCP Server 
Configuration ExampleThe common DHCP networking methods can be classified into two categories: 
One is that the DHCP server and the clients reside on the same subnetwork and 
they directly carry out the interaction of DHCP. Another one is that the DHCP 
server and the clients reside on different subnetworks and they must implement 
the allocation of IP addresses through the DHCP relay proxy. In both these cases, 
the DHCP configurations are the same.
I....

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...

Configure DHCP Relay 345
Figure 127   Schematic diagram of DHCP relay 
The above figure is the schematic diagram of DHCP relay. Its working principle is as 
follows:
After starting DHCP client, a configuration request message is broadcast and the 
DHCP relay router will send the message to the designated DHCP server on the 
other network after processing it properly. According to the information provided 
by the client, the server sends configuration information to the client via DHCP 
relay and...

346CHAPTER 21: CONFIGURING IP APPLICATION
UDP needs to be forwarded Broadcast messages of common protocols usually 
adopt UDP. The destination port number of UDP is configured to set the 
transparent transmission protocol. For example, transparent transmission of TFTP 
broadcast messages (port number 69) and DNS protocol broadcast messages (port 
number 53) can be configured. At most 20 transparent transmission forwarding 
protocols can be configured. 
Perform the following task in system view.
Ta b l e...