Displaying Dhcp Information; Denial Of Service Protection - Extreme Networks ExtremeWare XOS Guide Manual

Denial of Service Protection

The following commands allow you to configure the server. To configure the range of IP addresses
assigned by the DHCP server, use the following command:
configure vlan <vlan_name> dhcp-address-range <ipaddress1> - <ipaddress2>
To remove the address range information, use the following command:
unconfigure vlan <vlan_name> dhcp-address-range
To set how long the IP address lease assigned by the server exists, use the following command:
configure vlan <vlan_name> dhcp-lease-timer <lease-timer>
To set the default gateway, Domain Name Servers (DNS) addresses, or Windows Internet Naming
Service (WINS) server, use the following command:
configure vlan <vlan_name> dhcp-options [default-gateway | dns-server | wins-server]
<ipaddress>
To remove the default gateway, DNS server addresses, and WINS server information for a particular
VLAN, use the following command:
unconfigure vlan <vlan_name> dhcp-options
To remove all the DHCP information for a particular VLAN, use the following command:
unconfigure vlan <vlan_name> dhcp
You can clear the DHCP address allocation table selected entries, or all entries. You would use this
command to troubleshoot IP address allocation on the VLAN. To clear entries, use the following
command:
clear vlan <vlan_name> dhcp-address-allocation [[all {offered | assigned | declined |
expired}] | <ipaddress>]

Displaying DHCP Information

To display the DHCP configuration, including the DHCP range, DHCP lease timer, network login lease
timer, DHCP-enabled ports, IP address, MAC address, and time assigned to each end device, use the
following command:
show dhcp-server {vlan <vlan_name>}
The next two commands were retained for compatibility with earlier versions of ExtremeWare. To view
only the address allocation of the DHCP server on a VLAN, use the following command:
show vlan <vlan_name> dhcp-address-allocation
To view only the configuration of the DHCP server on a VLAN, use the following command:
show vlan <vlan_name> dhcp-config
Denial of Service Protection
A Denial-of-Service (DoS) attack occurs when a critical network or computing resource is overwhelmed
and rendered inoperative in a way that legitimate requests for service cannot succeed. In its simplest
form, a Denial of Service attack is indistinguishable from normal heavy traffic. Extreme Network
switches are not vulnerable to this simple attack because they are all designed to process packets in
239
ExtremeWare XOS 11.1 Concepts Guide