Troubleshooting High Availability


A trunk (also called LAG or port channel) can be configured automatically or can be defined manually with or without the LACP protocol.


Due to their resiliency and traffic load balancing, trunks can be used for inter-switch communication within a cluster (auto-LAG) or for general network connectivity (user-configured LAG).


You can verify a trunk (LAG) status with the command trunk-show:


CLI (network-admin@switch) > trunk-show format switch,name,ports,speed,lacp-mode,status


switch

----------

name

-------

ports

-------

speed

------

lacp-mode

-----------

status

--------

pnswitch1

ports1-4

1-4

10g

off

up

pnswitch1

ports5-8

5-8

10g

off

up

pnswitch1

ports9-12

9-12

10g

off

up

pnswitch1

ports13-16

13-16

10g

off

up

 


Trunks can be configured with or without LACP. The following example shows the LACP options available when creating a trunk:


CLI (network-admin@switch) > trunk-create name port1-4 ports 1,4 lacp-mode


Off

LACP is off

Passive

LACP passive mode

Active

LACP active mode


When LACP is set to active or passive mode it helps detect link and configuration changes, whereas in off mode it is up to the network admin to deal with the trunk bring up process and to avoid configuration mistakes/oversights (such as asymmetries in the configuration).


Clusters and vLAGs provide the underlying redundancy structure for network communications. You can check that a cluster and a vLAG are functioning properly with the following commands. First verify the cluster status (online or offline) with the command cluster-show:


CLI (network-admin@switch) > cluster-show


name

------

state

-------

cluster-node-1

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

cluster-node-2

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

tid

----

ports

-------

remote-ports

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

pnclusterodd

online

pnswitch1

pnswitch3

15

4,36,128

4,36,129

pnclustereven

online

pnswitch2

pnswitch4

0

4,8,128

4,8,129



Then verify the vLAG status(es) with the command vlag-show:


CLI (network-admin@pnswitch1) > vlag-show

 

name

------

cluster

--------

mode

-----

switch

-------

port

-----

peer-switch

-----------

peer-port

----------

status

------

local-state

-----------

lacp-mode

----------

pnvlag1

pnclusterodd

active-active

pnswitch1

trunk-to-plus

pnswitch3

trunk-to-plus

normal

enabled

up  off

pnvlag2  

pnclustereven

active-active

pnswitch2

49

pnswitch4

 18

normal

enabled

up  active


A vLAG is a logical entity that relies upon its port members (physical ports with an operational Layer 1 status) and upon the underlying cluster.


Therefore, first check that the vLAG status is normal and the state is “enabled,up”.


If there are problems with the vLAG, work back through the objects it depends on the cluster, and ultimately the physical ports and the cables.