5-5
Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
OL-29284-01, Release 6.x
Chapter 5 Configuring Trunking
Information About Trunking
Tip The preferred configuration on the Cisco MDS 9000 Family switches is one side of the trunk set to auto
and the other side set to on.
Note When connected to a third-party switch, the trunk mode configuration on E ports has no effect. The ISL
is always in a trunking disabled state. In the case of F ports, if the third-party core switch ACC's physical
FLOGI with the EVFP bit is configured, then EVFP protocol enables trunking on the link.
Trunk-Allowed VSAN Lists and VF_IDs
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 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.
Switch 1 (see Figure 5-3) 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 (see
Figure 5-3).
For all F, N, and NP ports, the default VF_ID is 1 when there is no VF_ID configured. The trunk-allowed
VF_ID list on a port is same as the list of trunk-allowed VSANs. VF_ID 4094 is called the control VF_ID
and it is used to define the list of trunk-allowed VF-IDs when trunking is enabled on the link.
If F port trunking and channeling is enabled, or if switchport trunk mode on is configured in NPV mode
for any interface, or if NP PortChannel is configured, the VSAN and VF-ID ranges available for the
configuration are as described in
Table 5-3.
Note If the VF_ID of the F port and the N port do not match, then no tagged frames can be exchanged.
Ta b l e 5-3 VSAN and VF-ID Reservations
VSAN or VF-ID Description
000h Cannot be used as virtual fabric identifier.
001h(1) to EFFh(3839) This VSAN range is available for user configuration.
F00h(3840) to FEEh(4078) Reserved VSANs and they are not available for user
configuration.
FEFh(4079) EVFP isolated VSAN.
FF0h(4080) to FFEh(4094) Used for vendor-specific VSANs.
FFFh Cannot be used as virtual fabric identifier.
