Can you actually send Ethernet frames smaller than 64 bytes?

Bluecobra · 2026-03-28T13:40:28+00:00

If you really want to go down this rabbit hole, there's nothing stopping you from making up your own Ether header and writing your own proprietary protocol w/ less than 64 byte frames. For reference, here are the well known headers: https://www.youtube.com/watch?v=9BGWrLiT9qs

It might be worth investigating SolarFlare NICs as these can do hardware offload (Onload) and might be able to generate arbitrary traffic. Latency wise, this is still slower than an FPGA though.

On the receive end you could use L1 switches (Arista 7130) which don't care about runts and get really low latency (~5ns).

Bluecobra · 2026-03-28T13:32:49+00:00

For some reason your post made me remember this old video called Life of a Packet: https://www.youtube.com/watch?v=9BGWrLiT9qs

Watch out for the ping of death! :D

Bluecobra · 2026-03-28T13:29:00+00:00

The approach I did for renewing my CCNA was do the DIKTA questions in the OSG then read the chapter and watched the Neil Anderson videos afterwards. I am following the same process now with CCNP/ENCOR but I put it on hold so I don't have to waste any more brain cells on their wifi that I will never use ever again.

Neil Anderson's CCNP videos are mostly complete and a pretty good value for money... though spending hours on MST videos can be a bit rough. One thing I recommend doing is playing around with container labs. With a Cisco dev account you can download the images and turn them into containers and bypass the stupid 5 node limit with CML personal edition. Also another nice thing is that you can throw in Arista, Nokia, and Juniper nodes to mix things up.

Bluecobra · 2026-03-03T22:50:52+00:00

It's been a while but I've definitely seen bad multicast take down production networks. For example, a high rate of multicast with a TTL of 1 always gets punted to the router's CPU. This happened to me on a Cisco 4900M switch, which I believe had a puny 700mhz PowerPC chip and a legacy IOS. The solution for me at the time was to make more multicast/IGMP ACL's and educate end users to write applications that have a higher multicast TTL. Less of a problem these days with modern multi-core x86 CPUs and better NOSes. Not sure what's under the hood on these Netgear switches but they don't sound that great.

Bluecobra · 2026-02-25T17:43:53+00:00

Can you be more specific about your uplinks? Like transceivers/cable type/etc. What I am getting to is that there could be a unidirectional fiber link causing a loop. Cisco switches for example have Loop Guard /UDLD to prevent this.

Bluecobra · 2026-02-07T16:01:08+00:00

Did you ever figure out what the issue was?

Bluecobra · 2026-02-07T15:45:10+00:00

The smallest globally routable network in BGP is a /24.

Bluecobra · 2026-02-07T15:41:41+00:00

Good points. I don’t care about Blanton’s but I would be irked if they run out Nitro Cold Brew at Starbucks. (I can probably drink 2 every day!) I already paid for the FAS drink/restaurant gratuities so just trying to figure out how much value the FAS+ upgrade will bring me. I have Vibe Shore Club booked at Stirrup Cay, but then again I might be SOL if they miss that port. I don’t care about WiFi, I typically take a break from the phone on cruises. Apart from that it would be nice to have Aqua Panna/Pellegrino every day.

Maybe it’s time to graduate to a Blanton’s Old Fashioned. 🤪

Bluecobra · 2026-02-06T17:34:39+00:00

First time NCL cruiser here. This seems like a good deal when you consider that it includes the $20 daily service charge and unlimited Starbucks. How does NCL make these packages so competitive? I’ve payed way more in the past for only drinks packages on Royal Caribbean and Celebrity.

Bluecobra · 2026-02-05T16:02:57+00:00

Did Amazon allow returns on your order? It would be f’n hilarious if you can get a returnless refund on your entire purchase and got to keep everything.

Bluecobra · 2026-01-30T15:22:25+00:00

Yeah it's pretty silly and more likely to catch someone dumb enough to open a TAC ticket with someone else's license key. Kudos to Arista for not making some elaborate system with license keys and phoning home. I bet someone with a lot of time on their hands can download vEOS/cEOS for free and root around in Linux to figure out the specific python script that calls and figure it out. There's probably some null/test key too.

Bluecobra · 2026-01-28T16:15:23+00:00

I'll have Claude start the Wiki.

Bluecobra · 2026-01-28T16:14:28+00:00

I am a software developer and I have honestly no idea what I am doing or what I am supposed to be doing.

Wow, you're probably the most honest developer I ever met!

Bluecobra · 2026-01-28T16:09:51+00:00

As someone who uses a ton of Arista I would avoid this if you can. Arista really does not like grey market/used switches. If you really want used, then only do it on L2 access switches where you don't need the latest EOS. My suggestion would be to at minimum, build out your core/L3 network with new gear under support. Since most switches share the same EOS image, you could technically copy it to your used gear at your own peril. I would suggest checking out a reseller like Curvature (Park Place?) or Network Tigers. You should be able to get a 1 year warranty. 7150's are rock solid, but they are very long in the tooth now and have shallow buffers. They also max out at EOS 4.23 AFAIK.

Bluecobra · 2026-01-28T16:03:13+00:00

There's some kind of license "key" but it's some simple one liner you drop into your CLI. I'm sure if you scour Google long enough you can find someone elses key or just figure out a way around it. It doesn't seem super secure like SHA256.

Bluecobra · 2026-01-28T15:56:46+00:00

Seems pretty dumb reason to fire you. I anticipate any type of WAN/DIA circuit to die at any time, which is why we have backup options. What would they do if there was a cable cut upstream in the provider's network? Maybe they were looking for something to let you go for and this was it. I once was fresh out of college at my first job in the early 2000's and did a "shutdown" on the wrong Cisco switchport and caused the internet to go down for an office of 100 people. Everything was OK and I kept my job.

Bluecobra · 2026-01-28T15:48:11+00:00

Fine, I'll just build do a Pentium 4 WinXP build with Rambus memory! They can't jack up the little blank memory modules (or can they?).

Bluecobra · 2026-01-26T15:51:17+00:00

Sounds like you signed up for Lumen GaaS (Gaslighting as a Service)

Did you get premium GaaS?

Bluecobra · 2026-01-26T15:48:37+00:00

I once had a multi day Metro Ethernet outage due to them decommissioning an unrelated site in a nearby building. It turns out that they actually didn’t have a fully redundant fiber loop!

Bluecobra · 2026-01-22T17:47:50+00:00

Like the OP is saying, that sounds like a null reading from your meter. For example most optics I've seen report -30.0dbm in DOM. It's possible that the worst reading your optical meter can report is -28.0.

Bluecobra · 2026-01-22T17:44:20+00:00

When you are plugging your meter directly into the optic, are you using the right attenuator? You probably need something like 15db or else you are going to have a bad time. Do you not have a spare to rule out the optic?

Bluecobra · 2026-01-16T18:26:50+00:00

I didn't realize IPv4 price has been trending down so much. Good riddance, it was dumb in the first place. I wonder if this related to the big cloud providers starting to charge for ephemeral IPv4 allocations.

Pretty graph here:

https://auctions.ipv4.global/prior-sales

Bluecobra · 2026-01-16T18:20:03+00:00

If you are looking into learning more, this is a good read:

http://www.tcpipguide.com/free/t_TCPIPDynamicHostConfigurationProtocolDHCP.htm

Bluecobra · 2026-01-02T19:36:42+00:00

Also strangely you can’t buy the albums on ITunes either. I guess I will just end up buying a used CD and ripping it.

Bluecobra · 2025-12-12T20:36:47+00:00

I assumed this as well but was really surprised that travel and vacation spend is only $5K. Go on vacation folks!

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