Administrator Guide

You can also manually congure an IP address for the VLAN 1 default management interface using the CLI. If no user-congured
IP address exists for the default VLAN management interface exists and if the default VLAN IP address is not in the startup
conguration, the Aggregator will automatically obtain it using DHCP.
• The default VLAN 1 with all ports congured as members is the only L3 interface on the Aggregator. When the default
management VLAN has a DHCP-assigned address and you recongure the default VLAN ID number, the Aggregator:
– Sends a DHCP release to the DHCP server to release the IP address.
– Sends a DHCP request to obtain a new IP address. The IP address assigned by the DHCP server is used for the new default
management VLAN.
How DHCP Client is Implemented
The Aggregator is enabled by default to receive DHCP server-assigned dynamic IP addresses on an interface. This setting persists
after a switch reboot. If you enter the shutdown command on the interface, DHCP transactions are stopped and the dynamically-
acquired IP address is saved. Use the
show interface type slot/port command to display the dynamic IP address and
DHCP as the mode of IP address assignment. If you later enter the no shutdown command and the lease timer for the dynamic IP
address has expired, the IP address is uncongured and the interface tries to acquire a new dynamic address from DHCP server.
If you later enter the no shutdown command and the lease timer for the dynamic IP address has expired, the IP address is
released.
When you enter the release dhcp command, although the IP address that was dynamically-acquired from a DHCP server is
released from an interface, the ability to acquire a new DHCP server-assigned address remains in the running conguration for the
interface. To acquire a new IP address, enter either the renew dhcp command at the EXEC privilege level or the ip address
dhcp
command at the interface conguration level.
If you enter renew dhcp command on an interface already congured with a dynamic IP address, the lease time of the dynamically
acquired IP address is renewed.
Important: To verify the currently congured dynamic IP address on an interface, enter the show ip dhcp lease
command. The show running-configuration command output only displays ip address dhcp; the currently
assigned dynamic IP address is not displayed.
DHCP Client on a Management Interface
These conditions apply when you enable a management interface to operate as a DHCP client.
• The management default route is added with the gateway as the router IP address received in the DHCP ACK packet. It is
required to send and receive trac to and from other subnets on the external network. The route is added irrespective of
whether the DHCP client and server are on same or dierent subnets. The management default route is deleted if the
management IP address is released like other DHCP client management routes.
• ip route for 0.0.0.0 takes precedence if it is present or added later.
• Management routes added by a DHCP client display with Route Source as DHCP in the show ip management route and
show ip management-route dynamic command output.
• Management routes added by DHCP are automatically reinstalled if you congure a static IP route with the ip route
command that replaces a management route added by the DHCP client. If you remove the statically congured IP route using
the no ip route command, the management route is reinstalled. Manually delete management routes added by the DHCP
client.
• To reinstall management routes added by the DHCP client that is removed or replaced by the same statically congured
management routes, release the DHCP IP address and renew it on the management interface.
• Management routes added by the DHCP client have higher precedence over the same statically congured management route.
Static routes are not removed from the running conguration if a dynamically acquired management route added by the DHCP
client overwrites a static management route.
• Management routes added by the DHCP client are not added to the running conguration.
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Dynamic Host Conguration Protocol (DHCP)