3Com 10014299 Display and Debug Domain Name Resolution, Display and Debug domain name resolution

VLAN Configuration 329

Display and Debug

Domain Name

Resolution

Delete static domain name resolution table item undo ip host domain-name

ip-address

By default, the system has no static domain name resolution mapping.

Pay attention that when adding a domain name mapping, if the same hostname has been input twice, the current configuration will overwrite the previous one. A static domain name resolution table can maintain a maximum of 50 mapping relationships between domain names and IP addresses.

Table 361 Display and Debug domain name resolution

Operation	Command
Display static domain name resolution table item	display ip host

VLAN Configuration To facilitate the mobility of computers in the network and save bandwidth, we can create VLAN in LAN Switch to meet various requirements. After creating VLAN in LAN Switch port, data communication can be easily implemented within the same VLAN. However, the different VLANs are isolated from each other, so it is necessary to transmit packet between different VLAN in the same way as transmitting it between different LAN segments. The forwarding function between VLANs on the 3Com Router series is implemented by Ethernet interface and it supports IP and IPX packet. In order to save port resources, several subinterfaces can be encapsulated on one Ethernet interface and every subinterface acts as an independent Ethernet interface. Therefore, a physical Ethernet interface can implement data forwarding between several VLANs as shown in the figure below.

Figure 121 Networking diagram mode of VLAN

Product 1	Product 2	Product 3
Bridge/LAN Switch	Workstation		Workstation
			Floor 3
Router
File Server			(Accounting)
Fast
Ethernet			Workstation
Bridge/LAN Switch
	File Server		Floor 2
Workstation			(Marketing)
Bridge/LAN Switch			File Server
	Workstation		Floor 1
Workstation
			(R&D)
VLAN 1	VLAN 2	VLAN 3

In accordance with the IEEE 802.1Q, to implement the VLAN functionality of the 3Com Router series, a 4-byte VLAN tag is placed between the source/destination MAC address of the original Ethernet frame header and the Type field to mark the VLAN message. The format of VLAN tag is shown as below.