How is Cisco Evolving Network Fabrics? Well, It hasn’t been long since Cisco announced their second iteration of gear in the Nexus space. They’ve addressed a number of areas such as power consumption with 9 Watts per port, as well as scalability, and cost, realizing that cost should be lowered so as not to have a demand for what Ron Fuller called “Un-obtanium”, out there. In fact, they are even addressing a Graphical Interface for configuration (which Ivan is probably still choking about!) The information on the release can be found here, and I’d rather not delve into an area that has been discussed already.

Instead, what I thought was cool, was when Ron asked the question, “What if I could do a traceroute at layer 2?” Then he follows with “Well you can with Pong.” Immediately I was interested as were many attending Networking Field Day. I believe that Ivan Pepelnjak of IOS Hints asked for an explanation of how this works, but I don’t think we ever got there.

In short, Pong, is a layer 2 trace route function that is built into the Nexus platform. The actual definition of PONG from the Cisco Release notes states that PONG is the ability to do a traceroute based on the MAC addresses of the destination endpoint, and to provide a latency and connectivity check, using IEEE1588v2 for latency measurement. PONG can be enable with the Enhanced Layer 2 Package (N7K-EL21K9) license.

While I don’t have my own equipment to test this, and I dont see much documentation on how it actually functions, I did dig up an example of PONG in action. In this example we see PONG between FabricPath switch-ids.

switch# configure terminal
switch(config)# pong destination-swid 3506 destination-mac 001b.54c2.9a43 vlan 1 count 3
Packet No. 1
--- ----------------- --------------------------
Hop Switch-id Switching time (sec, nsec)
--- ----------------- --------------------------
1 0-1b-54-c2-9a-41 0 4752
2 0-1b-54-c2-9a-43 0 544258088
3 0-1b-54-c2-9a-41 0 4792
Round trip time: 0sec 15416 nsec
Packet No. 2
--- ----------------- --------------------------
Hop Switch-id Switching time (sec, nsec)
--- ----------------- --------------------------
1 0-1b-54-c2-9a-41 0 4752
2 0-1b-54-c2-9a-43 0 522744240
3 0-1b-54-c2-9a-41 0 4736
Round trip time: 0sec 15368 nsec
Packet No. 3
--- ----------------- --------------------------
Hop Switch-id Switching time (sec, nsec)
--- ----------------- --------------------------
 1 0-1b-54-c2-9a-41 0 4752
 2 0-1b-54-c2-9a-43 0 521869920
 3 0-1b-54-c2-9a-41 0 4800
 Round trip time: 0sec 15360 nsec

You can see from the output that pong provides Layer 2 hop and second/nanosecond latency calculations. You can find additional examples in the Cisco Nexus 7000 Series NX-OS Troubleshooting Guide — Troubleshooting Tools and Methodology

Yes, just another tool for troubleshooting to put in the “Geek Utility Belt” if you will. I wonder what this would look like in a GUI? (Can you hear my snarky tone?)

Side Note

For many of my readers, the Nexus Platform and data center switching may not be in your wheel house. If you want to start getting your feet wet in Data Center Switching I’d recommend some of the introductory posts over at Etherealmind.com or why not sign up for one f Ivans Webinars?

Disclaimer

Seems everyone that attended the recent Networking Field Day is doing these so I might as well also. Many of the posts I have coming out are related to information I learned, or opinions I have formed from attending the Networking Field Day 2 which is an event that is run by Stephen Foskett from Gestalt IT. Delegates receive some swag, food, transportation, and so on, as well as travel and hotel accommodations to the event. The vendors understand that we have the right to like, or not like what they have to teach/show us. If I like something I see I may blog or tweet about it. If not, I probably won’t. The point is, these are my opinions, thoughts and understandings and not anything I have been paid to write for anyone.