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Configuration procedure
1. Add all the ports on Switch B to VLAN 10, and configure the IP address of VLAN-interface 10 on
Switch A. (Details not shown)
2. Configure Switch A as a DHCP server
# Configure DHCP address pool 0.
<SwitchA> system-view
[SwitchA] dhcp enable
[SwitchA] dhcp server ip-pool 0
[SwitchA-dhcp-pool-0] network 10.1.1.0 mask 255.255.255.0
3. Configure Host A as DHCP client, and Host B as user respectively. (Details not shown)
4. Configure Switch B
# Enable DHCP snooping.
<SwitchB> system-view
[SwitchB] dhcp-snooping
[SwitchB] interface ethernet 1/0/3
[SwitchB-Ethernet1/0/3] dhcp-snooping trust
[SwitchB-Ethernet1/0/3] quit
# Enable ARP detection for VLAN 10.
[SwitchB] vlan 10
[SwitchB-vlan10] arp detection enable
# Configure the upstream port as a trusted port and the downstream ports as untrusted ports (a port is an
untrusted port by default).
[SwitchB-vlan10] interface ethernet 1/0/3
[SwitchB-Ethernet1/0/3] arp detection trust
[SwitchB-Ethernet1/0/3] quit
# Configure a static IP source guard binding entry on interface Ethernet 1/0/2.
[SwitchB] interface ethernet 1/0/2
[SwitchB-Ethernet1/0/2] ip source binding ip-address 10.1.1.6 mac-address 0001-0203-0607
[SwitchB-Ethernet1/0/2] quit
# Enable the checking of the MAC addresses and IP addresses of ARP packets.
[SwitchB] arp detection validate dst-mac ip src-mac
After the preceding configurations are complete, when ARP packets arrive at interfaces Ethernet 1/0/1
and Ethernet 1/0/2, their MAC and IP addresses are checked, and then the packets are checked
against the static IP source guard binding entries and finally DHCP snooping entries.
ARP restricted forwarding configuration example
Network requirements
As shown in Figure 130, Switch A acts as a DHCP server. Host A acts as a DHCP client. Host B’s IP
address is 10.1.1.6, and its MAC address is 0001-0203-0607. Port isolation configured on Switch B
isolates the two hosts at Layer 2, which can communicate with the gateway Switch A. Ethernet 1/0/1,
Ethernet 1/0/2 and Ethernet 1/0/3 belong to VLAN 10. Switch B is enabled with DHCP snooping, and
has ARP detection enabled in VLAN 10.
Configure Switch B to still perform port isolation on ARP broadcast requests.
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