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Monitoring DHCP Services

Purpose

A switch or router can operate as a DHCP server. Use the monitoring functionality to view information about dynamic and static DHCP leases, conflicts, pools, and statistics.

Action

To monitor the DHCP server in the J-Web interface, select Monitor > Services > DHCP.

To monitor the DHCP server in the CLI, enter the following CLI commands:

show system services dhcp binding
show system services dhcp conflict
show system services dhcp pool
show system services dhcp statistics
show system services dhcp relay-statistics
show system services dhcp global
show system services dhcp client

Meaning

Table 1 summarizes the output fields in DHCP displays in the J-Web interface.

Table 1: Summary of DHCP Output Fields

Field	Values	Additional Information
Global tab
Name	This column displays the following information: Boot lease length Domain Name Name servers Server identifier Domain search Gateway routers WINS server Boot file Boot server Default lease time Minimum lease time Maximum lease time
Value	Displays the value for each of the parameters in the Name column.
Bindings tab
Allocated Address	List of IP addresses the DHCP server has assigned to clients.
MAC Address	Corresponding media access control (MAC) address of the client.
Binding Type	Type of binding assigned to the client: dynamic or static.	DHCP servers can assign a dynamic binding from a pool of IP addresses or a static binding to one or more specific IP addresses.
Lease Expires	Date and time the lease expires, or never for leases that do not expire.
Pools tab
Pool Name	Subnet on which the IP address pool is defined.
Low Address	Lowest address in the IP address pool.
High Address	Highest address in the IP address pool.
Excluded Addresses	Addresses excluded from the address pool.
Clients tab
Interface Name	Name of the logical interface.
Hardware Address	Vendor identification.
Status	State of the client binding.
Address Obtained	IP address obtained from the DHCP server.
Update Server	Indicates whether server update is enabled.
Lease Obtained	Date and time the lease was obtained.
Lease Expires	Date and time the lease expires.
Renew	Reacquires an IP address from the server for the interface. When you click this option, the command sends a discover message if the client state is INIT and a renew request message if the client state is BOUND. For all other states it performs no action.
Release	Clears other resources received earlier from the server, and reinitializes the client state to INIT for the particular interface.
Conflicts tab
Detection Time	Date and time the client detected the conflict.
Detection Method	How the conflict was detected.	Only client-detected conflicts are displayed.
Address	IP address where the conflict occurs.	The addresses in the conflicts list remain excluded until you use the clear system services dhcp conflict command to manually clear the list.
DHCP Statistics
Relay Statistics tab
Packet Counters	Displays the number of packet counters.
Dropped Packet Counters	Graphically displays the number of dropped packet counters.
Statistics tab
Packets dropped	Total number of packets dropped and the number of packets dropped due to a particular condition.
Messages received	Number of BOOTREQUEST, DHCPDECLINE, DHCPDISCOVER, DHCPINFORM, DHCPRELEASE, and DHCPREQUEST messages sent from DHCP clients and received by the DHCP server.
Messages sent	Number of BOOTREPLY, DHCPACK, DHCPOFFER, and DHCPNAK messages sent from the DHCP server to DHCP clients.