Book excerpt from NX-OS and Cisco Nexus Switching

Excerpt from NX-OS and Cisco Nexus Switching: Next-Generation Data Center Architectures.

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In addition to interfaces, other physical resources can be allocated to an individual VDC, including IPv4 route memory, IPv6 route memory, port-channels, and SPAN sessions. Configuring these values prevents a single VDC from monopolizing system resources. Example 1-14 demonstrates how to accomplish this.

Example 1-14  Allocating System Resources

egypt(config)# vdc coreegypt(config-vdc)# limit-resource port-channel minimum 32 maximum equal-to-minegypt(config-vdc)# limit-resource u4route-mem minimum 32 maximum equal-to-minegypt(config-vdc)# limit-resource u6route-mem minimum 32 maximum equal-to-minegypt(config-vdc)# limit-resource vlan minimum 32 maximum equal-to-minegypt(config-vdc)# limit-resource vrf minimum 32 maximum equal-to-min

Defining the VDC HA policy is also done within the VDC configuration sub-mode. Use the ha-policy command to define the HA policy for a VDC as demonstrated in Example 1-15.

Example 1-15  Changing the HA Policy for a VDC

egypt(config)# vdc coreeqypt(config-vdc)# ha-policy dual-sup bringdown

The HA policy will depend based on the use-case or VDC role. For example, if you have dual-supervisor modules in the Nexus 7000 chassis or if the VDC role is development/test, the VDC HA policy may be to just shut down the VDC. If the VDC role is for the core and aggregation use case the HA policy would be switchover.


The troubleshooting sections introduce basic concepts, methodology, and general troubleshooting guidelines for problems that might occur when configuring and using Cisco NX-OS.

show Commands

Table 1-2 lists sample EXEC commands showing the differences between IOS and NX-OS

Table 1-2  Sample EXEC Commands Showing the Differences Between IOS and NX-OS.




Displays the running configuration

show runningconfig

show runningconfig

Displays the startup configuration

show startupconfig

show startupconfig

Displays the status of a specified

show etherchannel #

show port channel #

portchannel interface

Displays the current boot variables

show boot

show boot

Displays all environmental parameters

show environment

show environment

Displays the percentage of fabric utilized per module

show fabric

utilization show hardware fabric- utilization [detail]

Displays the supervisors high availability status

show redundancy

show system redundancy status

Displays CPU and memory usage data

show process cpu

show system resources

Displays specific VRF information

show ip vrf name

show vrf name

debug Commands

Cisco NX-OS supports an extensive debugging feature set for actively troubleshooting a network. Using the CLI, you can enable debugging modes for each feature and view a real-time updated activity log of the control protocol exchanges. Each log entry has a timestamp and is listed chronologically. You can limit access to the debug feature through the CLI roles mechanism to partition access on a per-role basis. Although the debug commands show real-time information, you can use the show commands to list historical and real-time information.

Caution - Caution  Use the debug commands only under the guidance of your Cisco technical support representative because debug commands can impact your network/device performance.

Save debug messages to a special log file, which is more secure and easier to process than sending the debug output to the console.

By using the ? option, you can see the options that are available for any feature. A log entry is created for each entered command in addition to the actual debug output. The debug output shows a timestamped account of the activity that occurred between the local device and other adjacent devices.

You can use the debug facility to track events, internal messages, and protocol errors. However, you should be careful when using the debug utility in a production environment because some options might prevent access to the device by generating too many messages to the console or creating CPU-intensive events that could seriously affect network performance.

You can filter out unwanted debug information by using the debug-filter command. The debug-filter command enables you to limit the debug information produced by related debug commands.

Example 1-16 limits EIGRP hello packet debug information to Ethernet interface 1/1.

Example 1-16  Filtering debug Information

switch# debug-filter ip eigrp interface ethernet 1/1switch# debug eigrp packets hello</code>


Throughout the book, you see a common topology for demonstration purposes. Figure 1-6 depicts the physical topology.

Figure 1-6

Physical Topology for Book Demonstration Purposes

Further Reading

NX-OS Feature Navigator:

NX-OS Nexus 7000 Supported MIB List:

NX-OS Nexus 5000 Supported MIB List:

NX-OS Nexus 1000V Supported MIB List:

© Copyright Pearson Education. All rights reserved.

Copyright © 2010 IDG Communications, Inc.

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