The trunk link transparently transmits VLAN packets between switches.
l
Backbone line
The trunk link transmits packets belonging to multiple VLANs.
Figure 3-7
Trunk link communication
DeviceA
VLAN 2
VLAN 3
Port4
Port1
Port3
Port2
Host A
Host B
DeviceB
Trunk Link
, the trunk link between DeviceA and DeviceB must both support the
intra-communication of VLAN 2 and the intra-communication of VLAN 3. Therefore, the ports
at both ends of the trunk link must be configured to belong to both VLANs. That is, Port2 on
DeviceA and Port1 on DeviceB must belong to both VLAN 2 and VLAN 3.
Host A sends a frame to Host B in the following process:
1.
The frame is first sent to Port4 on DeviceA.
2.
A tag is added to the frame on Port4. The VID field of the tag is set to 2, that is, the ID of
the VLAN to which Port4 belongs.
3.
DeviceA queries its MAC address table for the MAC forwarding entry with the destination
MAC address of Host B.
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If this entry exists, DeviceA sends the frame to the outbound interface Port2.
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If this entry does not exist, DeviceA sends the frame to all interfaces bound to VLAN
2 except for Port4.
4.
Port2 sends the frame to DeviceB.
5.
After receiving the frame, DeviceB queries its MAC address table for the MAC forwarding
entry with the destination MAC address of Host B.
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If this entry exists, DeviceB sends the frame to the outbound interface Port3.
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If this entry does not exist, DeviceB sends the frame to all interfaces bound to VLAN
2 except for Port1.
6.
Port3 sends the frame to Host B.
Inter-VLAN Communication
After VLANs are configured, hosts in different VLANs cannot directly communicate with each
other. To implement communication between VLANs, use either of the following methods:
Huawei AR530&AR550 Series Industrial Switch Routers
Configuration Guide - Ethernet Switching
3 VLAN Configuration
Issue 01 (2014-11-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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