Troubleshooting High Availability

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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

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

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 layout vertical

name:                pnvlag1

cluster:        pnclusterodd

mode:                active-active

switch:        pnswitch1

port:                trunk-to-plus

peer-switch:        pnswitch3

peer-port:        trunk-to-plus

status:        normal

local-state:        enabled

lacp-mode:        up  off

name:                pnvlag2

cluster:        pnclustereven

mode:                active-active

switch:        pnswitch2

port:                49

peer-switch:        pnswitch4

peer-port:        18

status:        normal

local-state:        enabled

lacp-mode:        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.