Cisco Nexus & Catalyst Tshoot | Nexus ASA ASR Packet Capture

Ratnesh K 2xCCIE

Dip Dive into Nexus troubleshooting plus cat4500 tshoot & Cat3850 high cpu .

What you’ll learn

  • Solid understanding of Nexus troubleshooting.

Course Content

  • Nexus 7 K Troubleshooting –> 7 lectures • 5hr 10min.
  • Catalyst 4500 Tshoot & Catalyst 3850 CPU tshoot –> 4 lectures • 3hr 19min.
  • Cisco Nexus ASR ASA Packet Capture Techniques –> 5 lectures • 3hr 27min.

Cisco Nexus & Catalyst Tshoot | Nexus ASA ASR Packet Capture


Dip Dive into Nexus troubleshooting plus cat4500 tshoot & Cat3850 high cpu .

•Work towards turning initial problem description into platform specific problem description.

•Define “broken” and /or “not working”

•Understand how whatever is “not working” should be working

•Determine possible triggers, patterns, timestamps etc.

•Understand the topology when relevant

“Initial” problem description: We’re having protocol <x> changing states  intermittently

“platform specific” / desired problem description: OSPF is flapping , only b/t these two specific links, not an issue on any other OSPF interfaces, and it looks as if box <x> stops transmitting hello packets from the CPU whenever it’s being  polled by this SNMP device every 5 minutes.


Nexus troubleshooting part 1 – 7

Cat 4500 troubleshooting  part 1-3

Cat 3850 high cpu

• Contrary to popular belief…..

TAC esc, BU esc, DEs, TMEs, cs-nexus7000 do not have a magic wand to answer vague scenarios such as previous “initial” problem description.

•Hence the importance to get to a platform specific / component problem description.

•DEs that monitor the alias are not typically “network” troubleshooters, but are “feature” troubleshooters. So “escalating to DE/BU” is not a productive step unless the necessary info is gathered prior.

•Show techs are ‘not’ meant to simply be gathered and then passed to your direct escalation or alias.

It is ok “not to  know” what you’re looking for in every show tech.


++++++ADDED ++++++++

Good idea of the capabilities of Cisco switches/routers in terms of various   troubleshooting tools, especially packet capture tools.  Ability to choose the right tool to troubleshoot, which helps for timely resolution of the problem.

The most important function of packet capture is network detection. The process of packet capture is similar in essence to telephone wiretapping, as it detects everything going through the computer networks. The main function of it is to monitor network performance and troubleshoot any problems which may arise. Sniffers can also capture data from diverse parts of the network using a monitoring port. This type of interface intercepts data from different points and sends them to the network administrator, to be decoded and analysed.

Topics Covered :

Flexible NetFlow (FnF)

Embedded Packet Capture Tools


Ethanalyzer and NetDR

VACL and ACL Capture


Putting It All Together

Summary and Take Away

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