Dhcp Filtering; Dhcp Packet Filtering; Dhcp Server Packet Filtering - SMC Networks 7824M/VSW - annexe 1 Manual

CLI
8.6.10
8.6.10.1
8.6.10.2
336

DHCP Filtering

DHCP Packet Filtering

For the switch, it is possible to block the specific client with MAC address. If the MAC ad-
dress blocked by administrator requests an IP address, the server does not assign IP ad-
dress. This function can provide the security of DHCP server.
Not to assign IP address for specific client of a port, use the following command.
Command
ip dhcp filter-port PORTS
no ip dhcp filter-port PORTS
Not to assign IP address for specific client with a specific MAC address, use the following
command.
Command
ip dhcp filter-address
ADDR
no ip dhcp filter-address
MAC-ADDR

DHCP Server Packet Filtering

Dynamic Host Configuration Protocol (DHCP) makes DHCP server assign IP address to
DHCP clients automatically and manage the IP address. Most ISP operators provide the
service as such a way. At this time, if a DHCP client connects with the equipment that can
be the other DHCP server such as Internet access gateway router, communication failure
might be occurred.
DHCP filtering helps to operate DHCP service by blocking DHCP request which enters
through subscriber's port and goes out into uplink port or the other subscriber's port and
DHCP reply which enters to the subscriber's port.
In the Fig. 8.37, server A has the IP area from 192.168.10.1 to 192.168.10.10. Suppose a
user connects with client 3 that can be DHCP server to A in order to share IP address
from 10.1.1.1 to 10.1.1.10.
Here, if client 1 and client 2 are not blocked from client 3 of DHCP server, client 1 and cli-
ent 2 will request and receive IP from client 3 so that communication blockage will be oc-
curred. Therefore, the filtering function should be configured between client 1 and client 3,
client 2 and client 3 in order to make client 1 and client 2 receive IP without difficulty from
DHCP server A.
Mode
Configures a port in order not to assign IP address.
Global
Disables DHCP packet filtering.
Mode
Blocks a MAC address in case of requesting IP ad-
MAC-
dress.
MAC-ADDR: client's MAC address
Global
Disables DHCP MAC filtering.
Management Guide
TigerAccess™ EE
Description
Description
SMC7824M/VSW