Nexus 5000 FAQ: What is the difference between the VLAN ID displayed in the NX-OS Ethanalyzer and the VLAN ID on a Cisco Nexus 5000 Series Switch?

Introduction

This document describes the relationship between the VLAN ID seen in Ethanalyzer traces and the VLAN ID on a Cisco Nexus 5000 Series Switch.

Prerequisites

Requirements

Cisco recommends that you have knowledge of these topics:

• Knowledge of Cisco NX-OS CLI
• Knowledge of Fibre Channel over Ethernet (FCoE)
  
  

Components Used

The information in this document is based on Cisco Nexus 5000 and 5500 Series Switches.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

What is the difference between the VLAN ID displayed in the NX-OS Ethanalyzer and the VLAN ID on a Cisco Nexus 5000 Series Switch?

Ethanalyzer does not show the actual FCoE VLAN ID in the VID field of the 802.1q header. This section shows traces of two FCoE connections. The Qlogic CNA uses FCoE VLAN/VSAN 100, and the Cisco P81E (Monterey Park Adapter) uses FCoE VLAN/VSAN 30. The trace shows a VID of 13 and 14 respectively.

QLOGIC FIP Keepalives (Configured for FCoE VLAN/VSAN 100)

Monterey Park (P81e) FIP Solicitation (Configured for FCoE VLAN/VSAN 30)

Ethanalyzer will not show the actual decimal VLAN ID value that you would see in an inline trace. Ethanalyzer shows the N5K internal Canonical VLAN ID (CVID) value. Here is one way to map it back:

N5K# show system internal fcfwd fwcvidmap cvid 

Canonical VLAN-ID based FWCVIDMAP table-(all values in hex)
------------------------------------------------------------------------------
CVID   Type UCD  VID    Bcast_Index    Mcast_Index    MVR_Ctrl_Index
----   ---- ---- ---    -------------- -------------- --------------
0x0001 enet 0x01 0x0fc8 0100.0000.000b 0100.0000.000c 0100.0000.0004
0x0002 enet 0x01 0x0fc9 0100.0000.0000 0100.0000.0000 0100.0000.0000
0x0003 enet 0x01 0x0fcb 0100.0000.0000 0100.0000.0000 0100.0000.0000
0x0004 enet 0x01 0x0001 0100.0000.001d 0100.0000.001d 0100.0000.0004
0x0005 enet 0x01 0x0000 0100.0000.0000 0100.0000.0000 0100.0000.0000
0x0006 enet 0x02 0x0000 0100.0000.000a 0100.0000.000a 0100.0000.000a
0x0007 enet 0x02 0x0001 0100.0000.000a 0100.0000.000a 0100.0000.000a
0x000d enet 0x01 0x0064 0100.0000.001e 0100.0000.001e 0100.0000.0004 - vlan 100
0x000e enet 0x01 0x001e 0100.0000.0020 0100.0000.0020 0100.0000.0004 - vlan 30
0x0fff enet 0x01 0x0fca 0100.0000.0002 0100.0000.0002 0100.0000.0ffd
0x0000 fc   0x0e 0x0000 0100.0000.0000 0100.0000.0000 0100.0000.0000
0x0008 fc   0x0e 0x0ffe 0100.0000.0004 0100.0000.0004 0100.0000.0004
0x0009 fc   0x0e 0x0001 0100.0000.0004 0100.0000.0004 0100.0000.0004
0x000a fc   0x0e 0x0fef 0100.0000.0004 0100.0000.0004 0100.0000.0004
0x000c fc   0x0e 0x0005 0100.0000.0004 0100.0000.0004 0100.0000.0004
0x000d fc   0x0e 0x0064 0100.0000.0004 0100.0000.0004 0100.0000.0004 - vsan 100
0x000e fc   0x0e 0x001e 0100.0000.0004 0100.0000.0004 0100.0000.0004 - vsan 30
 
 
N5k# show flogi database 
--------------------------------------------------------------------------------
INTERFACE    VSAN    FCID           PORT NAME               NODE NAME       
--------------------------------------------------------------------------------
vfc1981      100   0xbc0000  21:00:00:c0:dd:15:d1:7d 20:00:00:c0:dd:15:d1:7d - Qlogic
vfc1982      30    0xb90000  20:00:e8:b7:48:4e:32:54 10:00:e8:b7:48:4e:32:54 - Monterey Park

Total number of flogi = 2.

N5K# sh vlan fcoe
Original VLAN ID        Translated VSAN ID      Association State
----------------        ------------------      -----------------

      30                        30               Operational
      100                       100              Operational

 
       
N5K# show platform fcfib vsan 30
(SD=S_ID/D_ID, SDO=S_ID/D_ID/OX_ID)

    VSAN         CVSAN      State   LoadBal   IOD   IOD_State
  30(0x001e)    14(0x000e)   active    SDO      N        none
 
 
N5K# show platform fcfib vsan 100
(SD=S_ID/D_ID, SDO=S_ID/D_ID/OX_ID)

    VSAN         CVSAN      State   LoadBal   IOD   IOD_State
 100(0x0064)    13(0x000d)  active    SDO      N        none

Canonical VLAN (CVID) 13 (0x000d) maps to FCoE VLAN 100 (0x0064), which maps to VSAN 100; and CVID 14 (0x000e) maps to FCoE VLAN 30 (0x001e), which maps to VSAN 30.

The same CVID (0x000e ? decimal 14) is used to represent the external FCoE VLAN and VSAN regardless of whether they use the same number (recommended) or a different number. For example: 

Change the FCoE VLAN to VSAN mapping to be FCoE VLAN 630 to VSAN 30, instead of using VLAN 30 to VSAN 30.

N5K# show vlan fcoe
Original VLAN ID        Translated VSAN ID      Association State
----------------        ------------------      -----------------

      100                       100              Operational
      630                       30               Operational

Notice the CVID (0x000e - decimal 14) is the same number:

N5K# show system internal fcfwd fwcvidmap cvid 
Canonical VLAN-ID based FWCVIDMAP table- (All values in hex)
------------------------------------------------------------------------------
CVID   Type UCD  VID    Bcast_Index    Mcast_Index    MVR_Ctrl_Index
----   ---- ---- ---    -------------- -------------- --------------
0x0001 enet 0x01 0x0fc8 0100.0000.000b 0100.0000.000c 0100.0000.0004
0x0002 enet 0x01 0x0fc9 0100.0000.0000 0100.0000.0000 0100.0000.0000
0x0003 enet 0x01 0x0fcb 0100.0000.0000 0100.0000.0000 0100.0000.0000
0x0004 enet 0x01 0x0001 0100.0000.001d 0100.0000.001d 0100.0000.0004
0x0005 enet 0x01 0x0000 0100.0000.0000 0100.0000.0000 0100.0000.0000
0x0006 enet 0x02 0x0000 0100.0000.000a 0100.0000.000a 0100.0000.000a
0x0007 enet 0x02 0x0001 0100.0000.000a 0100.0000.000a 0100.0000.000a
0x000d enet 0x01 0x0064 0100.0000.001e 0100.0000.001e 0100.0000.0004
0x000e enet 0x01 0x0276 0100.0000.0024 0100.0000.0024 0100.0000.0004 - VLAN 630
0x0fff enet 0x01 0x0fca 0100.0000.0002 0100.0000.0002 0100.0000.0ffd
0x0000 fc   0x0e 0x0000 0100.0000.0000 0100.0000.0000 0100.0000.0000
0x0008 fc   0x0e 0x0ffe 0100.0000.0004 0100.0000.0004 0100.0000.0004
0x0009 fc   0x0e 0x0001 0100.0000.0004 0100.0000.0004 0100.0000.0004
0x000a fc   0x0e 0x0fef 0100.0000.0004 0100.0000.0004 0100.0000.0004
0x000c fc   0x0e 0x0005 0100.0000.0004 0100.0000.0004 0100.0000.0004
0x000d fc   0x0e 0x0064 0100.0000.0004 0100.0000.0004 0100.0000.0004
0x000e fc   0x0e 0x001e 0100.0000.0004 0100.0000.0004 0100.0000.0004 - VSAN 30

Here is another way to determine the internal VLAN mapping to external VLAN mapping:

N5k# show platform afm info global 
Gatos Hardware version 0 
Hardware instance mapping
-------------------------
Hardware instance: 0 asic id: 0 slot num: 0
Hardware instance: 1 asic id: 1 slot num: 0
Hardware instance: 2 asic id: 2 slot num: 0
Hardware instance: 3 asic id: 3 slot num: 0
Hardware instance: 4 asic id: 4 slot num: 0
Hardware instance: 5 asic id: 5 slot num: 0
Hardware instance: 6 asic id: 6 slot num: 0
Hardware instance: 7 asic id: 0 slot num: 1
Hardware instance: 8 asic id: 1 slot num: 1
Hardware instance: 9 asic id: 0 slot num: 3
Hardware instance: 10 asic id: 1 slot num: 3
AFM Internal Status
-------------------
[unknown label ]: 324
[no free statistics counter ]: 2
[number of verify ]: 59
[number of commit ]: 59
[number of request ]: 6163
[tcam stats full ]: 2
Vlan mapping table
------------------
Ext-vlan: 1 - Int-vlan: 66 
Ext-vlan: 2 - Int-vlan: 62 
Ext-vlan: 101 - Int-vlan: 61 
Ext-vlan: 102 - Int-vlan: 60 
Ext-vlan: 103 - Int-vlan: 59 
Ext-vlan: 104 - Int-vlan: 58 
Ext-vlan: 105 - Int-vlan: 57 
Ext-vlan: 106 - Int-vlan: 56 
Ext-vlan: 107 - Int-vlan: 55 
Ext-vlan: 108 - Int-vlan: 54 
Ext-vlan: 109 - Int-vlan: 53 
Ext-vlan: 110 - Int-vlan: 52 
Ext-vlan: 111 - Int-vlan: 51 
Ext-vlan: 112 - Int-vlan: 50