Guidelines And Limitations; Guidelines For Configuring Port Monitor Check Interval - Cisco MDS 9000 Series Configuration Manual

Guidelines and Limitations

Guidelines and Limitations
From Cisco MDS NX-OS Release 7.3(x) or earlier, ports were classified as port type access ports, trunks, or
all in the port monitor. Access ports were mode (T)F ports and trunks were mode (T)E ports (ISLs). Since
ports connecting to Cisco NPV switches are mode (T)F, they were included under the port type access ports.
These Cisco NPV ports behave like ISLs, but they are a multi-user connection to a switch and not an end
device. Because of this, it is not preferred to take portguard actions on the access ports for port-monitor
counters pertaining to slow-drain conditions.
From Cisco MDS NX-OS Release 8.1(1), the port monitor has implemented a different classification
mechanism. Instead of port type access ports, trunks, or all, a logical type core, edge, or all value can be
configured. Core ports are mode T(E) ports and ports connecting core switches to Cisco NPV switches. Edge
ports are mode F ports connecting to end devices. With this new classification, portguard actions can safely
be configured especially pertaining to slow drain type conditions such that when the problem is detected and
the action is taken, it is only on the ports connected to end devices. It is still valid to configure portguard
actions for logical type core ports, but this should only be done for counters pertaining to physical errors on
the port (such as link loss, invalid words, invalid CRC, and so on).
The MDS NX-OS will automatically classify all F port-channels and trunking F ports as logical-type core. It
will classify all non-trunking F ports, including those to both Cisco and non-Cisco NPV switches, as logical-type
edge.
If a Cisco NPV switch or non-Cisco NPV switch cannot take portguard types of actions then classifying the
ports connected to it as logical-type edge is appropriate.
The logical type of a port is displayed using the show interface and show interface brief commands.
Note
When you use the logical-type command to define a port type, the command overrides the default port type.
In the port monitor, you can configure the policies per port type (core and edge) so that portguard action can
be taken on the ports when certain criteria are met. Generally, edge policies are configured to take portguard
action on ports and the core policies will not be configured with portguard action. If the link between a core
switch and a Cisco NPV switch is treated as an edge port, portguard action is taken on such ports which will
result in the loss of connectivity to all the devices connected to the Cisco NPV switch.
For any Cisco NPV switch that supports its own Port Monitor policies, it is best to implement these portguard
actions on the Cisco NPV switch itself. Hence, we recommend that all non-trunking F ports connected to
Cisco NPV switches be manually configured to a logical type of core, using the switchport logical-type core
command. This will ensure that port monitor core policy is applied to the port connected to a Cisco NPV
switch. We also recommend that Port Monitor be implemented on the Cisco NPV switch, if supported.
For more information, see

Guidelines for Configuring Port Monitor Check Interval

• Check interval should be configured before activating any port monitor policies.
Cisco MDS 9000 Series Interfaces Configuration Guide, Release 8.x
38
Interface Modes, on page 17.
Configuring Interfaces