ACFE · SWITCHING

Alcatel-Lucent: VLANs and 802.1Q tagged ports

Two OmniSwitches each have a host that belongs in VLAN 10. AOS has no configuration mode: you create the VLAN and assign ports to it with global vlan … members commands. The host ports are untagged members; the link between the switches is a tagged (802.1Q) member.

ALE ACFE track · Alcatel-Lucent AOS · 5 objectives

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Objectives

The simulator ticks each one as soon as the network meets it.

Create VLAN 10 on SW1 and SW2 (vlan 10 admin-state enable).
Make port 1/1/2 an untagged member of VLAN 10 on both switches.
Make port 1/1/1 a tagged member of VLAN 10 on both switches.
Check show vlan members: VLAN 10 lists 1/1/2 untagged and 1/1/1 qtagged.
Ping PC2 (192.168.10.20) from PC1.

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Before you start

An OmniSwitch port belongs untagged to one VLAN (its default VLAN, VLAN 1 out of the box) and can carry any number of VLANs tagged. vlan 10 members port 1/1/1 tagged is the AOS equivalent of a Cisco trunk allowing VLAN 10. The change is live at once; write memory saves it.

Concept

VLANs and access ports

A VLAN splits one physical switch into separate broadcast domains. An access port belongs to exactly one VLAN, and frames are only forwarded between ports of the same VLAN.

Concept

802.1Q trunks: VLAN tags on the wire

A trunk carries many VLANs over one link. To keep them apart, the sending switch inserts a 4-byte 802.1Q tag into each frame saying which VLAN it belongs to; the receiving switch reads the tag and removes it before delivering the frame to an access port.