Configure Fabric Attach in an SMLT

The following example describes FA configuration and behavior in a dual-homed SMLT deployment.

The following figure shows a simple FA solution in a dual-homed SMLT deployment. In this deployment, a pair of BEB switches (BEB A and BEB B) operating as IST peers are configured as the FA Server. An access switch or a wiring closet switch configured as an FA Proxy connects to the FA Server. The FA Proxy advertises I-SID-to-VLAN assignment mappings to the FA Server. Both BEB switches receive the mapping information using LLDP PDUs containing assignment TLVs. The switch that learns the mapping first considers the I-SID to be discovered locally and creates the I-SID on its device. The mapping information is then shared with its IST peer switch. When the peer switch receives the mapping across IST in a new SMLT message, it too creates the I-SID on its device. This I-SID however, is considered to be discovered remotely because it is learnt from synchronization with the peer switch. The mappings can also be learned on the FA Server from both LLDP PDUs and from IST synchronization.

Click to expand in new window
FA configuration in dual-homed SMLT

Before you begin

Ensure that the proxy device (for example, an access switch) is properly configured for FA. See the corresponding product documentation for information on how to configure FA on the switch.

Procedure

  1. Configure SMLT and vIST on switches BEB A and BEB B.
    Caution

    Caution

    For the IST peer switches acting as the FA Server to transmit the same FA System ID (based on the virtual MAC), SMLT configuration on both the switches must be the same.

    For detailed information on configuring SMLT and vIST, see MultiLink Trunking and Split MultiLink Trunking.

Configure BEB A and BEB B as the FA Server

Perform the following configuration on each switch.

  1. Enter Global Configuration mode:

    enable

    configure terminal

  2. Enable FA globally:

    fa enable

  3. Enter MLT interface configuration mode:

    interface mlt <1–512>

  4. Enable FA on the MLT:

    fa enable

    Note

    Note

    Enabling FA automatically enables message authentication. Also, the authentication key is set to the default value and appears encrypted on the output.

  5. Optional: Configure an FA authentication key with a value different from that of the default value:

    fa authentication-key [WORD<0-32>]

    Caution

    Caution

    When you configure the FA authentication key, you must configure the same value on both BEB switches in the SMLT.

Verify global and MLT-level FA configuration on BEB A and BEB B:

  1. Verify global configuration of FA using one of the following commands:
    • show fa

    • show fa agent

  2. Verify MLT-level (interface-level) configuration of FA:

    show fa interface

Verify FA discovery on BEB A and BEB B:

  1. Verify discovery of the FA Proxy.

    show fa elements

View FA I-SID-to-VLAN assignments on BEB A and BEB B:

  1. View the FA I-SID-to-VLAN assignments:

    show fa assignment

    To view FA I-SID-to-VLAN assignments on specific ports, enter:

    show fa assignment {slot/port[/sub-port] [-slot/port[/sub-port]] [,...]}

Verify creation of Switched UNI I-SIDs on BEB A and BEB B:

  1. Verify creation of Switched UNI (ELAN) I-SIDs:
    • View ELAN I-SID information using show i-sid elan.

    • View ELAN I-SID information on a specific MLT using show mlt i-sid [<1–512>].

      Note

      Note

      Viewing ELAN I-SID information on an MLT is very useful to understand the origin of the I-SID, when multiple client or proxy devices connecting to the FA Server using SMLT MLT advertise the same I-SID-to-VLAN mappings. In the event of a link failure on an MLT, the origin of the I-SID helps determine on which MLT, and thereby from which proxy or client device, the mappings were successfully learnt.

Examples

SMLT configuration on BEB A and BEB B:

On BEB A:

Switch:1>en
Switch:1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Switch:1(config)#interface mlt 1
Switch:1(config)#smlt

On BEB B:

Switch:2>en
Switch:2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Switch:2(config)#interface mlt 1
Switch:2(config)#smlt

vIST configuration on BEB A and BEB B:

On BEB A:

Switch:1(config)#vlan create 2261 type port-mstprstp 0
Switch:1(config)#vlan i-sid 2261 1502261
Switch:1(config)#interface vlan 2261
Switch:1(config)#ip address 192.0.2.0 255.255.255.0 2

Configure BEB B (IP address 192.0.2.1) as the IST peer.

Switch:1(config)#virtual-ist peer-ip 192.0.2.1 vlan 2261
Switch:1(config)#show virtual-ist
Switch:1(config)#exit

On BEB B:

Switch:2(config)#vlan create 2261 type port-mstprstp 0
Switch:2(config)#vlan i-sid 2261 1502261
Switch:2(config)#interface vlan 2261
Switch:2(config)#ip address 192.0.2.1 255.255.255.0 2

Configure BEB A (IP address 192.0.2.1) as the IST peer.

Switch:2(config)#virtual-ist peer-ip 192.0.2.1 vlan 2261
Switch:2(config)#show virtual-ist
Switch:2(config)#exit

FA configuration on BEB A:

Enable FA globally and on the MLT:

Switch:1(config)#fa enable
Switch:1(config)#show fa
========================================================================
                          Fabric Attach Configuration
========================================================================
                            FA Service : enabled
                       FA Element Type : server
                 FA Assignment Timeout : 240
                  FA Discovery Timeout : 240
                     FA Provision Mode : spbm

Optionally, configure an FA authentication key with the value dual-homed-smlt. Ensure that you configure the same value on both switches BEB A and BEB B.

Switch:1(config)#interface mlt 1
Switch:1(config-mlt)#fa authentication-key dual-homed-smlt

Enable FA on the MLT:

Switch:1(config-mlt)#fa enable
Switch:1(config-mlt)#exit
Switch:1(config)#show fa interface

====================================================================
                            Fabric Attach Interfaces
====================================================================
INTERFACE    SERVER   MGMT     MGMT     MSG AUTH MSG AUTH           
             STATUS   ISID     CVID     STATUS   KEY                
--------------------------------------------------------------------
Mlt1         enabled  0        0        enabled  ****               

--------------------------------------------------------------------
 1 out of 1 Total Num of fabric attach interfaces displayed
--------------------------------------------------------------------

Verify discovery of the FA Proxy:

Switch:1(config)#show fa elements

================================================================================
                        Fabric Attach Discovery Elements
================================================================================
                         MGMT                                         ELEM ASGN
PORT   TYPE              VLAN STATE  SYSTEM ID                        AUTH AUTH
--------------------------------------------------------------------------------
3/21   proxy             2    T / S  10:cd:ae:09:40:00:20:00:00:01    AP   AP
3/22   proxy             2    T / S  10:cd:ae:09:40:00:20:00:00:01    AP   AP
3/23   proxy             2    T / S  10:cd:ae:09:40:00:20:00:00:01    AP   AP

================================================================================
                      Fabric Attach Authentication Detail
================================================================================
       ELEM OPER                      ASGN OPER
PORT   AUTH STATUS                    AUTH STATUS
--------------------------------------------------------------------------------
3/21   successAuth                    successAuth
3/22   successAuth                    successAuth
3/23   successAuth                    successAuth

State Legend: (Tagging/AutoConfig)
T= Tagged,    U= Untagged,    D= Disabled,    S= Spbm,    V= Vlan,    I= Invalid

Auth Legend:
AP= Authentication Pass,  AF= Authentication Fail,
NA= Not Authenticated,  N= None



--------------------------------------------------------------------------------

3 out of 3 Total Num of fabric attach discovery elements displayed

The FA Proxy advertises I-SID-to-VLAN assignment mappings to BEB A, on MLT ports 3/21 to 3/23. View the FA I-SID-to-VLAN assignments on BEB-A:

All ports in the MLT receive the FA assignment mappings, as shown in the following output.

Switch:1(config)#show fa assignment 
 
===================================================
            Fabric Attach Assignment Map 
==================================================
Interface  I-SID      Vlan       State      Origin
---------------------------------------------------
3/21       2          2          active     proxy
3/21       3          3          active     proxy
3/21       4          4          active     proxy
3/22       2          2          active     proxy
3/22       3          3          active     proxy
3/22       4          4          active     proxy
3/23       2          2          active     proxy
3/23       3          3          active     proxy
3/23       4          4          active     proxy     

FA configuration on BEB B:

Enable FA globally and on the MLT:

Switch:2(config)#fa enable
Switch:2(config)#show fa
========================================================================
                          Fabric Attach Configuration
========================================================================
                            FA Service : enabled
                       FA Element Type : server
                 FA Assignment Timeout : 240
                  FA Discovery Timeout : 240
                     FA Provision Mode : spbm

Configure the FA authentication key dual-homed-smlt. Ensure that you configure the same value as on BEB A.

Switch:2(config)#interface mlt 1
Switch:2(config-mlt)#fa authentication-key dual-homed-smlt

Enable FA on the MLT:

Switch:2(config-mlt)#fa enable
Switch:2(config-mlt)#exit
Switch:2(config)#show fa interface

====================================================================
                            Fabric Attach Interfaces
====================================================================
INTERFACE    SERVER   MGMT     MGMT     MSG AUTH MSG AUTH           
             STATUS   ISID     CVID     STATUS   KEY                
--------------------------------------------------------------------
Mlt1         enabled  0        0        enabled  ****               

--------------------------------------------------------------------
 1 out of 1 Total Num of fabric attach interfaces displayed
--------------------------------------------------------------------

Verify discovery of FA Proxy:

Switch:2(config)#show fa elements

================================================================================
                        Fabric Attach Discovery Elements
================================================================================
                         MGMT                                         ELEM ASGN
PORT   TYPE              VLAN STATE  SYSTEM ID                        AUTH AUTH
--------------------------------------------------------------------------------
3/17   proxy             2    T / S  10:cd:ae:09:40:00:20:00:00:01    AP   AP
3/18   proxy             2    T / S  10:cd:ae:09:40:00:20:00:00:01    AP   AP
3/19   proxy             2    T / S  10:cd:ae:09:40:00:20:00:00:01    AP   AP
3/20   proxy             2    T / S  10:cd:ae:09:40:00:20:00:00:01    AP   AP

================================================================================
                      Fabric Attach Authentication Detail
================================================================================
       ELEM OPER                      ASGN OPER
PORT   AUTH STATUS                    AUTH STATUS
--------------------------------------------------------------------------------
3/17   successAuth                    successAuth
3/18   successAuth                    successAuth
3/19   successAuth                    successAuth
3/20   successAuth                    successAuth

State Legend: (Tagging/AutoConfig)
T= Tagged,    U= Untagged,    D= Disabled,    S= Spbm,    V= Vlan,    I= Invalid

Auth Legend:
AP= Authentication Pass,  AF= Authentication Fail,
NA= Not Authenticated,  N= None



--------------------------------------------------------------------------------

4 out of 4 Total Num of fabric attach discovery elements displayed

The FA Proxy device advertises I-SID-to-VLAN assignment mapping requests to BEB B on MLT ports 3/17 to 3/20.

View FA I-SID-to-VLAN assignments on BEB-B:

Switch:2(config)#show fa assignment 3/17 
 
===================================================
            Fabric Attach Assignment Map 
==================================================
Interface  I-SID      Vlan       State      Origin
---------------------------------------------------
3/17       2          2          active     proxy 
3/17       3          3          active     proxy
3/17       4          4          active     proxy
    

Verify creation of FA Switched UNI (ELAN) I-SIDs on BEB A and BEB B:

Verify the creation of FA Switched UNI (ELAN) I-SIDs on BEB A and BEB B.

On BEB A:

Switch:1(config)#show i-sid elan 
===================================================================================
                                        Isid Info 
===================================================================================
ISID   ISID                    PORT               MLT          ORIGIN            ISID
ID     TYPE       VLANID       INTERFACES         INTERFACES                     NAME
-----------------------------------------------------------------------------------
2     ELAN       N/A          -                  c2:1         -  ---  -  -lr  -   ISID-2
3     ELAN       N/A          -                  c3:1         -  ---  -  -lr  -   ISID-3
4     ELAN       N/A          -                  c4:1         -  ---  -  -lr  -   ISID-4

ORIGIN Legend:
C: manually configured; D: discovered by FA or EPT
M: FA management; E: discovered by EAP; A: auto-sense
l: discover by local switch  r: discover by remote VIST switch
8k_fanout:1(config-if)#shlw mlt i-sid

View the I-SID information for MLT 1 on BEB A.

Switch:1(config)#show mlt i-sid 1

================================================================================
                                 MLT Isid Info
================================================================================
              ISID                   ISID
MLTID IFINDEX ID       VLANID C-VID  TYPE     ORIGIN              ISID     BPDU
                                                                  NAME 
--------------------------------------------------------------------------------
1     6144    2        N/A    2      ELAN     -  ---  -  -lr  -   ISID-2
1     6144    3        N/A    3      ELAN     -  ---  -  -lr  -   ISID-3
1     6144    4        N/A    4      ELAN     -  ---  -  -lr  -   ISID-4
--------------------------------------------------------------------------------

3 out of 3 Total Num of i-sid endpoints displayed

ORIGIN Legend:
C: manually configured; D: discovered by FA or EPT
M: FA management; E: discovered by EAP; A: auto-sense
l: discover by local switch  r: discover by remote VIST switch
8k_fanout:1(config-if)#shlw mlt i-sid

On BEB B:

Switch:2(config)#show i-sid elan 
===================================================================================
                                        Isid Info 
===================================================================================
ISID  ISID                    PORT               MLT          ORIGIN            ISID
ID    TYPE       VLANID       INTERFACES         INTERFACES                     NAME 
------------------------------------------------------------------------------------
2     ELAN       N/A          -                  c2:1         -  ---  -  -lr  - ISID-2
3     ELAN       N/A          -                  c3:1         -  ---  -  -lr  - ISID-3
4     ELAN       N/A          -                  c4:1         -  ---  -  -lr  - ISID-4

ORIGIN Legend:
C: manually configured; D: discovered by FA or EPT
M: FA management; E: discovered by EAP; A: auto-sense
l: discover by local switch  r: discover by remote VIST switch
8k_fanout:1(config-if)#shlw mlt i-sid   

View the I-SID information for MLT 1 on BEB B.

Switch:1(config)#show mlt i-sid 1

================================================================================
                                 MLT Isid Info
================================================================================
              ISID                   ISID
MLTID IFINDEX ID       VLANID C-VID  TYPE  ORIGIN              ISID       BPDU
                                                               NAME
--------------------------------------------------------------------------------
1     6144    2        N/A    2      ELAN  -  ---  -  -lr  -   ISID-2
1     6144    3        N/A    3      ELAN  -  ---  -  -lr  -   ISID-3
1     6144    4        N/A    4      ELAN  -  ---  -  -lr  -   ISID-4
--------------------------------------------------------------------------------

3 out of 3 Total Num of i-sid endpoints displayed

ORIGIN Legend:
C: manually configured; D: discovered by FA or EPT
M: FA management; E: discovered by EAP; A: auto-sense
l: discover by local switch  r: discover by remote VIST switch
8k_fanout:1(config-if)#shlw mlt i-sid

The following section describes the behavior if, for example, a link failure occurs between the FA Proxy and BEB B, as shown in the following figure.

Click to expand in new window
FA behavior in dual-homed SMLT during a link failure

View the I-SID-to-VLAN assignments on BEB A:

Switch:1(config)#show fa assignment 3/21 
 
===================================================
            Fabric Attach Assignment Map 
==================================================
Interface  I-SID      Vlan       State      Origin    
---------------------------------------------------
3/21       2          2          active     proxy     
3/21       3          3          active     proxy     
3/21       4          4          active     proxy  

View the Switched UNI (ELAN) I-SIDs created on BEB A.

Switch:1(config)#show i-sid elan 
======================================================================================
                                        Isid Info 
======================================================================================
ISID   ISID                    PORT               MLT          ORIGIN             ISID
ID     TYPE       VLANID       INTERFACES         INTERFACES                      NAME
-------------------------------------------------------------------------------------
2      ELAN       N/A          -                  c2:1         -  ---  -  -l-  -  ISID-2 
3      ELAN       N/A          -                  c3:1         -  ---  -  -l-  -  ISID-3
4      ELAN       N/A          -                  c4:1         -  ---  -  -l-  -  ISID-4  

ORIGIN Legend:
C: manually configured; D: discovered by FA or EPT
M: FA management; E: discovered by EAP; A: auto-sense
l: discover by local switch  r: discover by remote VIST switch
8k_fanout:1(config-if)#shlw mlt i-sid 

View the I-SID information for MLT 1 on BEB A.

Switch:1(config)#show mlt i-sid 1

================================================================================
                                 MLT Isid Info
================================================================================
              ISID                   ISID
MLTID IFINDEX ID       VLANID C-VID  TYPE  ORIGIN             ISID       BPDU
                                                              NAME
--------------------------------------------------------------------------------
1     6144    2        N/A    2      ELAN  -  ---  -  -l-  -  ISID-2
1     6144    3        N/A    3      ELAN  -  ---  -  -l-  -  ISID-3
1     6144    4        N/A    4      ELAN  -  ---  -  -l-  -  ISID-4
--------------------------------------------------------------------------------

3 out of 3 Total Num of i-sid endpoints displayed

ORIGIN Legend:
C: manually configured; D: discovered by FA or EPT
M: FA management; E: discovered by EAP; A: auto-sense
l: discover by local switch  r: discover by remote VIST switch
8k_fanout:1(config-if)#shlw mlt i-sid

View the Switched UNI (ELAN) I-SIDs created on BEB B.

BEB-B:1(config-mlt)#show i-sid elan 
======================================================================================
                                        Isid Info 
======================================================================================
ISID   ISID                    PORT               MLT          ORIGIN            ISID
ID     TYPE       VLANID       INTERFACES         INTERFACES                     NAME
--------------------------------------------------------------------------------------
2      ELAN       N/A          -                  c2:1         -  ---  -  --r  - ISID-2
3      ELAN       N/A          -                  c3:1         -  ---  -  --r  - ISID-3
4      ELAN       N/A          -                  c4:1         -  ---  -  --r  - ISID-4

ORIGIN Legend:
C: manually configured; D: discovered by FA or EPT
M: FA management; E: discovered by EAP; A: auto-sense
l: discover by local switch  r: discover by remote VIST switch
8k_fanout:1(config-if)#shlw mlt i-sid

View the I-SID information for MLT 1 on BEB B.

Switch:1(config)#show mlt i-sid 1

================================================================================
                                 MLT Isid Info
================================================================================
              ISID                   ISID
MLTID IFINDEX ID       VLANID C-VID  TYPE     ORIGIN               ISID  BPDU
                                                                   NAME
--------------------------------------------------------------------------------
1     6144    2        N/A    2      ELAN     -  ---  -  --r  -    ISID-2
1     6144    3        N/A    3      ELAN     -  ---  -  --r  -    ISID-3
1     6144    4        N/A    4      ELAN     -  ---  -  --r  -    ISID-4
--------------------------------------------------------------------------------

3 out of 3 Total Num of i-sid endpoints displayed

ORIGIN Legend:
C: manually configured; D: discovered by FA or EPT
M: FA management; E: discovered by EAP; A: auto-sense
l: discover by local switch  r: discover by remote VIST switch
8k_fanout:1(config-if)#shlw mlt i-sid