Trunk-Allowed Vsan Lists - Cisco Nexus 5000 Series Configuration Manual

Configuring VSAN Trunking

Trunk-Allowed VSAN Lists

Each Fibre Channel interface has an associated trunk-allowed VSAN list. In TE-port mode, frames are
transmitted and received in one or more VSANs specified in this list. By default, the complete VSAN range
(1 through 4093) is included in the trunk-allowed list.
The common set of VSANs that are configured and active in the switch are included in the trunk-allowed
VSAN list for an interface, and they are called allowed-active VSANs. The trunking protocol uses the list of
allowed-active VSANs at the two ends of an ISL to determine the list of operational VSANs in which traffic
is allowed.
In the following figure, switch 1 has VSANs 1 through 5, switch 2 has VSANs 1 through 3, and switch 3 has
VSANs 1, 2, 4, and 5 with a default configuration of trunk-allowed VSANs. All VSANs configured in all
three switches are allowed-active. However, only the common set of allowed-active VSANs at the ends of
the ISL become operational as shown in below.
Figure 18: Default Allowed-Active VSAN Configuration
You can configure a selected set of VSANs (from the allowed-active list) to control access to the VSANs
specified in a trunking ISL.
Using the figure above as an example, you can configure the list of allowed VSANs on a per-interface basis
(see the following figure). For example, if VSANs 2 and 4 are removed from the allowed VSAN list of ISLs
connecting to switch 1, the operational allowed list of VSANs for each ISL would be as follows:
• The ISL between switch 1 and switch 2 includes VSAN 1 and VSAN 3.
• The ISL between switch 2 and switch 3 includes VSAN 1 and VSAN 2.
• The ISL between switch 3 and switch 1 includes VSAN 1, 2, and 5.
Cisco Nexus 5000 Series NX-OS SAN Switching Configuration Guide, Release 5.2(1)N1(1)
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Configuring VSAN Trunking
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