- Preface
- New and Changed Information
- Overview
-
- Configuring Ethernet Interfaces
- Configuring VLANs
- Configuring Private VLANs
- Configuring Access and Trunk Interfaces
- Configuring EtherChannels
- Configuring Virtual Port Channels
- Configuring Rapid PVST+
- Configuring Multiple Spanning Tree
- Configuring STP Extensions
- Configuring the MAC Address Table
- Configuring IGMP Snooping
- Configuring Traffic Storm Control
-
- Configuring Fibre Channel Interfaces
- Configuring Domain Parameters
- Configuring N Port Virtualization
- Configuring VSAN Trunking
- Configuring SAN Port Channel
- Configuring and Managing VSANs
- Configuring and Managing Zones
- Distributing Device Alias Services
- Configuring Fibre Channel Routing Services and Protocols
- Managing FLOGI, Name Server, FDMI, and RSCN Databases
- Discovering SCSI Targets
- Advanced Fibre Channel Features and Concepts
- Configuring FC-SP and DHCHAP
- Configuring Port Security
- Configuring Fabric Binding
- Configuring Fabric Configuration Servers
- Configuring Port Tracking
- Configuration Limits
- Index
Contents
- Configuring VSAN Trunking
- Configuring VSAN Trunking
- Information About VSAN Trunking
- VSAN Trunking Mismatches
- VSAN Trunking Protocol
- Configuring VSAN Trunking
- Guidelines and Restrictions
- Enabling or Disabling the VSAN Trunking Protocol
- About Trunk Mode
- Configuring Trunk Mode
- About Trunk-Allowed VSAN Lists
- Configuring an Allowed-Active List of VSANs
- Displaying VSAN Trunking Information
- Default Trunk Configuration Settings
Configuring VSAN Trunking
This chapter contains the following sections:
Configuring VSAN Trunking
Information About VSAN Trunking
VSAN trunking enables interconnect ports to transmit and receive frames in more than one VSAN, over the same physical link, using enhanced ISL (EISL) frame format (see the following figure).
VSAN trunking is supported on native Fibre Channel interfaces, but not on virtual Fibre Channel interfaces.
The VSAN trunking feature includes the following restrictions:
-
Trunking configurations are only applicable to E ports. If trunk mode is enabled in an E port and that port becomes operational as a trunking E port, it is referred to as a TE port.
-
The trunk-allowed VSANs configured for TE ports are used by the trunking protocol to determine the allowed-active VSANs in which frames can be received or transmitted.
-
If a trunking-enabled E port is connected to a third-party switch, the trunking protocol ensures seamless operation as an E port.
VSAN Trunking Mismatches
If you misconfigure VSAN configurations across E ports, issues can occur such as the merging of traffic in two VSANs (causing both VSANs to mismatch). The VSAN trunking protocol validates the VSAN interfaces at both ends of an ISL to avoid merging VSANs (see the following figure).
In this example, the trunking protocol detects potential VSAN merging and isolates the ports involved.
The trunking protocol cannot detect merging of VSANs when a third-party switch is placed in between two Cisco Nexus 5000 Series switches (see the following figure).
VSAN 2 and VSAN 3 are effectively merged with overlapping entries in the name server and the zone applications. The Cisco MDS 9000 Fabric Manager helps detect such topologies.
VSAN Trunking Protocol
The trunking protocol is important for E-port and TE-port operations. It supports the following capabilities:
-
Dynamic negotiation of operational trunk mode.
-
Selection of a common set of trunk-allowed VSANs.
-
Detection of a VSAN mismatch across an ISL.
By default, the VSAN trunking protocol is enabled. If the trunking protocol is disabled on a switch, no port on that switch can apply new trunk configurations. Existing trunk configurations are not affected: the TE port continues to function in trunk mode, but only supports traffic in VSANs that it negotiated with previously (when the trunking protocol was enabled). Other switches that are directly connected to this switch are similarly affected on the connected interfaces. If you need to merge traffic from different port VSANs across a nontrunking ISL, disable the trunking protocol.
Configuring VSAN Trunking
Guidelines and Restrictions
When configuring VSAN trunking, note the following guidelines:
-
We recommend that both ends of a VSAN trunking ISL belong to the same port VSAN. On platforms or fabric switches where the port VSANs are different, one end returns an error, and the other is not connected.
-
To avoid inconsistent configurations, disable all E ports with a shutdown command before enabling or disabling the VSAN trunking protocol.
Enabling or Disabling the VSAN Trunking Protocol
To enable or disable the VSAN trunking protocol, perform this task:
1.
switch# configuration terminal
2.
switch(config)# no trunk protocol enable
3.
switch(config)# trunk protocol enable
DETAILED STEPS
| Command or Action | Purpose |
|---|
About Trunk Mode
By default, trunk mode is enabled in all Fibre Channel interfaces. However, trunk mode configuration takes effect only in E-port mode. You can configure trunk mode as on (enabled), off (disabled), or auto (automatic). The default trunk mode is on. The trunk mode configurations at the two ends of the link determine the trunking state of the link and the port modes at both ends (see the following table).
|
Your Trunk Mode Configuration |
Resulting State and Port Mode |
||
|---|---|---|---|
|
Switch 1 |
Switch 2 |
Trunking State |
Port Mode |
|
On |
Auto or on |
Trunking (EISL) |
TE port |
|
Off |
Auto, on, or off |
No trunking (ISL) |
E port |
|
Auto |
Auto |
No trunking (ISL) |
E port |
The preferred configuration on the Cisco Nexus 5000 Series switches is that one side of the trunk is set to auto and the other is set to on.
 Note | When connected to a third-party switch, the trunk mode configuration has no effect. The ISL is always in a trunking disabled state. |
Configuring Trunk Mode
To configure trunk mode, perform this task:
1.
switch# configuration terminal
2.
switch(config)# interface
fc
slot/port
3.
switch(config-if)# switchport trunk mode on
4.
switch(config-if)# switchport trunk mode off
5.
switch(config-if)# switchport trunk mode auto
DETAILED STEPS
About 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.
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.
Consequently, VSAN 2 can only be routed from switch 1 through switch 3 to switch 2.
Configuring an Allowed-Active List of VSANs
To configure an allowed-active list of VSANs for an interface, perform this task:
1.
switch# configuration terminal
2.
switch(config)# interface
fc
slot/port
3.
switch(config-if)# switchport trunk allowed vsan
vsan-id
-
vsan-id
4.
switch(config-if)# switchport trunk allowed vsan add
vsan-id
5.
switch(config-if)# no switchport trunk allowed vsan
vsan-id
-
vsan-id
6.
switch(config-if)# no switchport trunk allowed vsan add
vsan-id
DETAILED STEPS
Displaying VSAN Trunking Information
The show interface command is invoked from the EXEC mode and displays VSAN trunking configurations for a TE port. Without any arguments, this command displays the information for all of the configured interfaces in the switch.
The following example shows how to display the trunk mode of a Fibre Channel interface:
switch# show interface fc3/3
fc3/3 is up
Hardware is Fibre Channel, SFP is short wave laser w/o OFC (SN)
Port WWN is 20:83:00:0d:ec:6d:78:40
Peer port WWN is 20:0c:00:0d:ec:0d:d0:00
Admin port mode is auto, trunk mode is on
...
The following example shows how to display the trunk protocol of a Fibre Channel interface:
switch# show trunk protocol
Trunk protocol is enabled
The following example shows how to display the VSAN information for all trunk interfaces:
switch# show interface trunk vsan 1-1000
fc3/1 is not trunking
...
fc3/11 is trunking
Belongs to san-port-channel 6
Vsan 1 is up, FCID is 0xef0000
Vsan 2 is up, FCID is 0xef0000
...
san-port-channel 6 is trunking
Vsan 1 is up, FCID is 0xef0000
Vsan 2 is up, FCID is 0xef0000
Default Trunk Configuration Settings
The following table lists the default settings for trunking parameters.
|
Parameters |
Default |
|---|---|
|
Switch port trunk mode |
On |
|
Allowed VSAN list |
1 to 4093 user-defined VSAN IDs |
|
Trunking protocol |
Enabled |