HP 5500 Ei 5500 Si Switch Series Configuration Guide

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Step Command Remarks 
3.  Configure a timeout waiting 
for ping responses.  dhcp server ping timeout
 
milliseconds   Optional. 
500 ms by default. 
The value 
0 indicates that no ping 
operation is performed. 
 
Enabling client offline detection 
With this feature enabled, the DHCP server considers a DHCP client goes offline when the ARP entry for  
the client ages out. In addition, it removes the client’s IP-to-MAC binding entry. 
Removing an ARP entry manually does not remove  the corresponding...

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Specifying the threshold for sending trap messages 
Configuration prerequisites 
Before you perform the configuration, use the snmp-agent target-host command to specify the 
destination address of the trap messages. For more information about the command, see the  Network 
Management and Monitoring Command Reference . 
Configuration procedure 
A DHCP server sends trap messages to the network management server when one of the following items 
reaches the specified threshold: 
•   The ratio of...

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Task Command  Remarks 
Display information about lease 
expiration. display dhcp server expired 
{ all  |  ip 
ip-address  |  pool  [ pool-name  ] } [ | { begin | 
exclude  | include  } regular-expression ]  Available in any view 
Display information about assignable 
IP addresses.  display dhcp server free-ip
 [ | { begin | 
exclude  | include  } regular-expression ]  Available in any view 
Display IP addresses excluded from 
automatic allocation in the DHCP 
address pool.  display dhcp server...

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Figure 29 Network diagram 
 
 
Configuration procedure 
1. Configure the IP address of VLAN -interface 2 on Switch A. 
 system-view 
[SwitchA] interface vlan-interface 2 
[SwitchA-Vlan-interface2] ip address 10.1.1.1 25 
[SwitchA-Vlan-interface2] quit 
2. Configure the DHCP server: 
# Enable DHCP. 
[SwitchA] dhcp enable 
# Enable the DHCP server on VLAN-interface 2. 
[SwitchA] interface vlan-interface 2 
[SwitchA-Vlan-interface2] dhcp select server global-pool 
[SwitchA-Vlan-interface2] quit 
#...

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Dynamic IP address assignment configuration example 
Network requirements 
•  As shown in  Figure 30, the DHCP s erver (Switch A) assigns IP addresses to clients in subnet 
1 0 .1.1. 0 / 2 4 ,  w h i c h  i s  s u b n e t t e d  i n t o  1 0 .1.1. 0 / 2 5  a n d  1 0 .1.1.12 8 / 2 5 .  
•   The IP addresses of VLAN-interfaces 1 and 2 on Switch A are 10.1.1.1/25 and 10.1.1.129/25 
respectively.  
•   In address pool 10.1.1.0/25, configure the address lease duration as ten days and twelve hours,...

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[SwitchA] dhcp server forbidden-ip 10.1.1.126 
[SwitchA] dhcp server forbidden-ip 10.1.1.254 
# Configure DHCP address pool 0 (subnet, client domain name suffix, and DNS server address). 
[SwitchA] dhcp server ip-pool 0 
[SwitchA-dhcp-pool-0] network 10.1.1.0 mask 255.255.255.0 
[SwitchA-dhcp-pool-0] domain-name aabbcc.com 
[SwitchA-dhcp-pool-0] dns-list 10.1.1.2 
[SwitchA-dhcp-pool-0] quit 
# Configure DHCP address pool 1 (subnet, gateway, lease duration, and WINS server). 
[SwitchA] dhcp server...

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Configuration procedure 
1. Specify IP addresses for the interfaces. (Details not shown.) 
2. Configure the DHCP server: 
# Enable DHCP. 
 system-view 
[SwitchA] dhcp enable 
# Enable the DHCP server on VLAN-interface 2. 
[SwitchA] interface vlan-interface 2 
[SwitchA-Vlan-interface2] dhcp select server global-pool 
[SwitchA-Vlan-interface2] quit 
# Configure DHCP address pool 0. 
[SwitchA] dhcp server ip-pool 0 
[SwitchA-dhcp-pool-0] network 10.1.1.0 mask 255.255.255.0 
[SwitchA-dhcp-pool-0] option...

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Configuring DHCP relay agent 
The DHCP relay agent configuration is supported only on Layer 3 Ethernet ports, Layer 3 aggregate 
interfaces, and VLAN interfaces. 
The term interface in the DHCP features refers to Layer 3 interfaces, including VLAN interfaces and 
route-mode (or Layer 3) Ethernet ports. You can set an  Ethernet port to operate in route mode by using the 
port  link-mode  route  command (see the  Layer 2—LAN Switching Configuration Guide ). 
Only HP 5500 EI switches support Layer 3...

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Figure 33 DHCP relay agent work process 
 
 
1. After receiving a DHCP-DISCOVER or DHCP-REQUE ST broadcast message from a DHCP client, 
the DHCP relay agent fills the giaddr field of th e message with its IP address and forwards the 
message to the designated DHCP server in unicast mode. 
2.  Based on the giaddr field, the DHCP server  returns an IP address and other configuration 
parameters to the relay agent, and the relay agent conveys them to the client. 
DHCP relay agent support for Option 82...

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If a client’s 
requesting 
messa
ge has… Handling 
strategy 
Padding format  The DHCP relay agent will… 
N/A verbose  Forward the message after adding the 
Option 82 padded in verbose format. 
N/A user-defined Forward the message after adding the 
user-defined Option 82. 
 
DHCP relay agent configuration task list 
 
Task Remarks 
Enabling DHCP 
Required 
Enabling the DHCP relay agent on an interface Required 
Correlating a DHCP server group with a relay agent interface  Required 
Configuring the...