During fabric expansion, the newly added switches may come up and form a fabric among themselves and elect a master before they are connected to the existing fabric. When the new fabric merges with the running fabric, it is possible for the master switch from the new leaf switches to overwrite the configuration in the existing fabric. It is critical to ensure a pair of leaf nodes in the existing fabric are configured to be the "preferred master" before expanding the fabric.
When you create an uplink to the external network using the SFS UI or OMNI, the preferred master is automatically set on all leaf switches in the fabric at that time.
Check preferred master status on existing leafs
Before connecting additional leaf switches to the fabric, verify the preferred master is set on at least one pair of leaf switches in the SmartFabric. This is done by running the show smartfabric cluster
command on each leaf in the existing fabric.
The output for at least one pair of leaf switches in the SmartFabric must show PREFERRED-MASTER
is set to true
. The following commands and output are from Leaf1A and Leaf1B:
Leaf1A# show smartfabric cluster
----------------------------------------------------------
CLUSTER DOMAIN ID : 100
VIP : fde2:53ba:e9a0:cccc:0:5eff:fe00:1100
ROLE : BACKUP
SERVICE-TAG : 690ZZP2
MASTER-IPV4 : 100.67.76.29
PREFERRED-MASTER : true
----------------------------------------------------------
Leaf1B# show smartfabric cluster
----------------------------------------------------------
CLUSTER DOMAIN ID : 100
VIP : fde2:53ba:e9a0:cccc:0:5eff:fe00:1100
ROLE : MASTER
SERVICE-TAG : 68X00Q2
MASTER-IPV4 : 100.67.76.29
PREFERRED-MASTER : true
----------------------------------------------------------
For the example in this guide, there are only two leaf switches in the SmartFabric at this stage of deployment. However, if there are additional leaf switches in the SmartFabric when the uplink is created, they will show that PREFERRED-MASTER
is set to true
.
If the fabric is previously expanded after the creating the uplink, the added leafs will not have PREFERRED-MASTER
set to true
. This is allowed if PREFERRED-MASTER
is set to true
on at least one pair of leaf switches in the SmartFabric.
Create an uplink if needed
PREFERRED-MASTER
set to
true
. If this does not apply, go to the
Check preferred master status on new leafs section.
If leaf switch pairs in the existing SmartFabric do not show PREFERRED-MASTER
set to true
, create an uplink by following the instructions in the Configure L2 uplinks to the external network or Configure L3 routed uplinks to the external network sections. After the uplink is created, return to the preceding section and check the preferred master setting again.
If you are using a demo or lab environment without the need for an uplink, create a temporary uplink to set all the leaf switches that are in the SmartFabric, to be the preferred master.
Create a temporary uplink as follows:
- On the SFS UI Home page, select 2. Create Uplink for External Network Connectivity.
- On the Uplink Details page:
- Next to Uplink Connectivity, leave Layer 2 selected.
- Enter a Name, such as temp.
- Click NEXT.
- On the Port Configuration page:
- Next to Racks, select any rack.
- Next to Configured Interfaces, select an available interface on either switch.
Note: You cannot use this interface for other purposes until you delete the uplink.
- Leave the LAG mode set to LACP.
- Click NEXT > FINISH.
After the uplink is created, verify all leaf switches in the SmartFabric show PREFERRED-MASTER
is set to true
.
To make the interface used in the temporary uplink available for other purposes, you can delete the uplink without affecting the preferred master setting by performing the following steps:
- On the SFS UI Uplinks page, select the uplink by name, temp in this example.
- Click DELETE > OK.
The port used for the temporary uplink is now available.
Check preferred master status on new leafs
Run the show smartfabric cluster
command on each leaf switch to be added to the SmartFabric and ensure none show PREFERRED-MASTER
set to true
. These switches should still be in their factory default mode, Full Switch mode, and the command and output should appear as follows on each switch:
OS10# show smartfabric cluster
----------------------------------------------------------
CLUSTER DOMAIN ID :
VIP : unknown
ROLE : unknown
SERVICE-TAG : unknown
MASTER-IPV4 :
PREFERRED-MASTER :
----------------------------------------------------------
If any leaf switch to be added to the SmartFabric shows PREFERRED-MASTER
is set to true
, the switch configuration should be cleared. This is done by taking each affected leaf switch out of SmartFabric mode and returning to Full Switch mode with the following commands:
OS10# configure terminal
OS10(config)# no smartfabric l3fabric
Reboot to change the personality? [yes/no]:y
After the switch reloads, run show smartfabric cluster
again on each affected leaf switch to confirm PREFERRED-MASTER
is no longer set to true
.