Configuring Active-Active vLAGs: a Step-by-Step Example



Note: There must be a physical connection between PN-0 and PN-1 before you can configure a vLAG.



Figure 7-8 - Active-Active vLAGs Toward a Dual-Homed Host and a Spine Switch

 

The sample topology in Figure: Active-Active vLAGs Toward a Dual-Homed Host and a Spine Switch above comprises three Pluribus switches that are part of the same fabric instance, fab-vLAG. The spine switch is set as RSTP root.


It’s important to note that ports 19-20 on PN-0 and ports 21-22 on PN-1 are connected to PN-2 (Spine). Ports 26, 27 interconnect PN-0 and PN-1 for the cluster link configuration required to set up a vLAG.


You can use the following steps to configure the above-pictured configuration with active-active vLAGs.


1) On the spine switch PN-2 use the following command:


CLI (network-admin@switch) > stp-modify bridge-priority 4096


2) Create the fabric and add the switches to it. On PN-2 use the fabric-create command:


CLI (network-admin@switch) > fabric-create name fab-VLAG


On PN-0 and PN-1 join the fabric:


CLI (network-admin@switch) > fabric-join name fab-VLAG


CLI (network-admin@switch) > fabric-join name fab-VLAG


3) Create VLAN connectivity from the spine switch all the way to the host. On PN-2 create for example VLAN 25 with scope fabric:


CLI (network-admin@switch) > vlan-create id 25 scope fabric


On PN-0 and PN-1 add VLAN 25 and untag the port connected to the host:


CLI (network-admin@switch) > vlan-port-add vlan-id 25 untagged ports 9


CLI (network-admin@switch) > vlan-port-add vlan-id 25 untagged ports 9


On PN-0 and PN-1 make the port connected to the host be an edge port:


CLI (network-admin@switch) > stp-port-modify port 9 edge


CLI (network-admin@switch) > stp-port-modify port 9 edge


4) Create a cluster configuration between PN-1 and PN-0. This creates the cluster link between ports 26, 27. On PN-0 enter the cluster-create command:


CLI (network-admin@switch) > cluster-create name VLAG cluster-node-1 PN-0 cluster-node-2 PN-1


5) In this example, for simplicity’s sake we will use static trunks toward the spine switch to create a vLAG. (LACP’s active mode can be used too, instead of off mode.) In this case you would first disable ports between PN-2 and PN-0 and then create a static trunk between them. Therefore, on PN-0 modify the ports facing PN-2 like so:


CLI (network-admin@switch) > port-config-modify port 19,20 disable


6) Create a two-port trunk between PN-0 and PN-2 with those ports:


CLI (network-admin@switch) > trunk-create name pn0-to-pn2 ports 19,20 lacp-mode off


CLI (network-admin@switch) > trunk-show format all layout vertical


switch:                PN-0

trunk-id:              128

name:                  pn0-to-pn2

ports:                 none

speed:                 disable

egress-rate-limit:     unlimited

autoneg:               off

jumbo:                 on

enable:                off

lacp-mode:             off

lacp-priority:         0

lacp-timeout:          slow

lacp-fallback:         bundle

lacp-fallback-timeout: 50

lacp-individual:       none

stp-port-cost:         2000

stp-port-priority:     128

reflect:               off

edge-switch:           no

pause:                 no

description:

loopback:              off

receive-only:          on

unknown-ucast-level:   %

unknown-mcast-level:   %

broadcast-level:       %

lport:                 0

rem-rswitch-port-mac:  00:00:00:00:00:00

rswitch-default-vlan:  0

status:

config:

trunk-hw-id:           0

send-port:             4294967295

routing:               yes

host-enable:           no

 

From the above output, you can verify the name and ID of the trunk configuration pn0-to-pn2. You need this information to create the vLAG.


7) On PN-1 repeat the same commands to create a static two-port trunk (LACP mode off) between PN-1 and PN-2. You would, therefore, disable ports between PN-2 and PN-1 and then create a static trunk between them. On PN-1 modify the ports facing PN-2 like so:


CLI (network-admin@switch) > port-config-modify port 21,22 disable


CLI (network-admin@switch) > trunk-create name pn1-to-pn2 ports 21,22 lacp-mode off


CLI (network-admin@switch) > trunk-show format all layout vertical


switch:               PN-1

intf:                 129

name:                 pn1-to-pn2

port:                 21-22

speed:                10g

autoneg:              off

jumbo:                off

enable:               off

lacp-mode:            off

lacp-priority:        32768

lacp-timeout:         slow

reflect:              off

edge-switch:          no

pause:                no

description:

loopback:             off

mirror-only:          off

lport:                0

rswitch-default-vlan: 0

port-mac-address:     06:60:00:02:10:80

status:

config:

send-port:            0

 

8) Create the vLAG from the bottom switches going upstream. Keep one side of the vLAG disabled while you configure this step. On PN-0 use the vlag-create command:


CLI (network-admin@switch) > vlag-create name to-spine port 128 peer-port 129 peer-switch PN-1 lacp-mode off mode active-active


On PN-2 create a normal 4-way trunk with the name trunk-pn:


CLI (network-admin@switch) > trunk-create name trunk-pn ports 19,20,21,22 lacp-mode off


9) Enable ports on all switches. On PN-2, PN-0 and PN-1 enter the port-config-modify command:


CLI (network-admin@switch) > port-config-modify port 19,20,21,22 enable


CLI (network-admin@switch) > port-config-modify port 19,20 enable


CLI (network-admin@switch) > port-config-modify port 21,22 enable


10) As a final step, create the server-facing active-active vLAG. In this case we will make it dynamic (LACP mode active). On PN-0 enter the vlag-create command:


CLI (network-admin@switch) > vlag-create name to-host port 9 peer-port 9 peer-switch PN-1 lacp-mode active mode active-active


Display and verify the vLAG configuration information:


CLI (network-admin@switch) > vlag-show format all layout vertical


id:               a000024:0

name:             to-host

cluster:          VLAG

mode:             active-active

switch:           PN-0

port:             9

peer-switch:      PN-1

peer-port:        9

failover-move-L2: no

status:           normal   

local-state:      enabled, up

lacp-mode:        active

lacp-timeout:     slow

lacp-key:         26460

lacp-system-id:   110013777969246