Vlan trunking, Figure 71, Confi – Brocade Communications Systems Brocate Ethernet Access Switch 6910 User Manual

Page 766

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Brocade 6910 Ethernet Access Switch Configuration Guide

53-1002581-01

VLAN Trunking

33

VLAN Trunking

Use the Interface > VLAN Trunking page to allow unknown VLAN groups to pass through the
specified interface.

CLI References

“vlan-trunking” on page 385

Command Usage

Use this feature to configure a tunnel across one or more intermediate switches which pass
traffic for VLAN groups to which they do not belong.

The following figure shows VLANs 1 and 2 configured on switches A and B, with VLAN trunking
being used to pass traffic for these VLAN groups across switches C, D and E.

FIGURE 71

Configuring VLAN Trunking

Without VLAN trunking, you would have to configure VLANs 1 and 2 on all intermediate
switches – C, D and E; otherwise these switches would drop any frames with unknown VLAN
group tags. However, by enabling VLAN trunking on the intermediate switch ports along the
path connecting VLANs 1 and 2, you only need to create these VLAN groups in switches A and
B. Switches C, D and E automatically allow frames with VLAN group tags 1 and 2 (groups that
are unknown to those switches) to pass through their VLAN trunking ports.

VLAN trunking is mutually exclusive with the “access” switchport mode (see

“Adding Static

Members to VLANs” on page 724

). If VLAN trunking is enabled on an interface, then that

interface cannot be set to access mode, and vice versa.

To prevent loops from forming in the spanning tree, all unknown VLANs will be bound to a
single instance (either STP/RSTP or an MSTP instance, depending on the selected STA mode).

If both VLAN trunking and ingress filtering are disabled on an interface, packets with unknown
VLAN tags will still be allowed to enter this interface and will be flooded to all other ports where
VLAN trunking is enabled. (In other words, VLAN trunking will still be effectively enabled for the
unknown VLAN).

Parameters

These parameters are displayed:

Interface – Displays a list of ports or trunks.

Port – Port Identifier. (Range: 1-12)

Trunk – Trunk Identifier. (Range: 1-12)

A

V1

B

C

D

E

V2

V1 V2

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