Christopher Hart

@HankYeomans Meaning, rip out hypervisors in favor of containerization? Or run things bare metal? Or move things to the cloud? Not sure what migration you’re advocating for 😅

If you’re a network engineer you should be asking yourself why are you running a hypervisor in your lab at all. In 2025 it’s time to reevaluate your lab and think outside of the same old, same old. You not only don’t need vmware you don’t need proxmox either.

It took us a while to deliver this (and, you guessed it, this was not entirely a technical problem). But we finally made it. Free CML tier, available w/ the 2.8 release. I am super glad and proud of the entire team for pulling this off! #ciscomodelinglabs #networksimulation 🍻

Massive News! Cisco Modeling Labs (CML) has a FREE tier! Download for free here: davidbombal.wiki/freecml #SponsoredbyCisco #ccna #ccnp #ccie #cisco #network #router #switch #firewall #study #career #Motivation @Cisco @LearningatCisco

@TracketPacer @dropout Sam Reich is a national treasure

we often sail the high seas in my home but we are all paying for our own individual subscriptions to @dropout bc it is that good

@gp_ifconfig Piping to just "json" is still kept around for legacy/backwards-compatible purposes, since some codebases may exclusively use the "json" keyword and not be aware of "json native".

@gp_ifconfig Great post Gian Paolo! Something worth noting - Nexus 9000s have a "json native" keyword you can pipe to, which solves the issue you noted with the inconsistent JSON schema.

[BLOG] #Cisco #NXOS supports #Python to collect command output. But which do you prefer between #JSON and #GNU text manipulation commands? In this post I tried both of them to collect transceiver temperatures ifconfig.it/hugo/2024/09/c…

@andylapteff I have a math-free document I wrote on this topic! The latter half is Nexus-specific (sort of - really, it's switching-specific) but the first half has generic definitions/examples of what a CRC is and what a CRC error means. cisco.com/c/en/us/suppor…

Can someone point me to good info on understanding Cyclic Redundancy Checks (CRCs)? I'm reading RFCs which are full of polynomial math. Say what now? I understand that CRC errors mean data was corrupted/destroyed in a frame/packet, but how do it know?? Please don't say "math."

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pyATS Tip: Customize SSH directly within the pyATS testbed using ssh_options. Ideal when needing to alter the algorithms used when connecting to older devices. Here is an example 👇

Great, quick article from @packetcoders on how to use Python's itertools.product() function to make nested for loops in #Python easier to read! packetcoders.io/how-to-flatten…

@DaryllSwer @Peter_Paluch That makes sense! I'd imagine a lot of that hinges on folks having "well-maintained networks", whereas in reality, many are fighting daily to keep the lights on. (this is not a criticism of anything you said, just remarking what the reality most likely is for most operators)

@_ChrisJHart @Peter_Paluch …hosts, application software) should have no problems with echo request/replies. RFC4890 covers ICMPv6 specifically it and too shares similar thoughts: #appendix-A.5" target="_blank" rel="nofollow noopener">datatracker.ietf.org/doc/html/rfc48…

Genuine question: If a firewall doesn't respond to pings by default, is it compliant w/ RFC 1122? Section 3.2.2.6 of RFC 1122 says: Every host MUST implement an ICMP Echo server function that receives Echo Requests and sends corresponding Echo Replies. datatracker.ietf.org/doc/html/rfc11…

@PeteCCDE @Peter_Paluch This is good context that I'm missing from a sales perspective due to a lack of experience, so thank you! When a customer puts out on an RFP to multiple vendors, can Vendor A see Vendor B's reply to the RFP and "contest" it?

@_ChrisJHart @Peter_Paluch In sales RFPs they usually give "partially complies" as a third option and you provide context and explanation

@Peter_Paluch Note that I'm still coming from a network device (router/switch/firewall/etc.) perspective for this RFC (I would argue they are hosts and subject to RFC 1122) but we could dodge that by applying the RFC to something like Windows Server 2022, which is undoubtedly a host.

@Peter_Paluch This is because when we review data sheets and technical documentation for products, they tend to state products are compliant in a Boolean manner. In reality, it seems like compliance can be partial, such as in this scenario, and the industry deems that acceptable.

To me, the former says "You should implement functionality to respond to pings, but it can be configurable and doesn't need to be on by default", while the latter is much more explicit about the intended default behavior.

But reading this clause carefully, I feel like "MUST implement an ICMP Echo server function" is meaningfully distinct from "MUST send corresponding Echo Replies after receiving Echo Requests".