alt for @[email protected]

Monday marks a quarter century of classless routing, or CIDR.

25 years since Class A, B, and C addresses were the standard.

On #CIDRDay, saying "class C address" outside a historic/ironic context is a request for enthusiastic wedgies.

Otherwise: cider!

How will you celebrate? #sysadmin #netadmin

Sep 21, 2018 at 4:43pmWeb
Show threadalt for @[email protected]Sep 21, 2018
Seriously: if you can't handle enough binary math to do CIDR, or you can't use a cheat sheet and remember a few basic netmasks, you shouldn't be a #netadmin.
Show threadYour's Truly Sep 21, 2018
@mwlucas well, thank glob i picked up Javascript b/c i know i cant do that.
Show threadalt for @[email protected]Sep 21, 2018
@somarasu also: ah, there you are!
Show threadYour's Truly Sep 21, 2018
@mwlucas Yes! Im just now re-following the people i followed on my old account; hex.bz might go down in a couple months so im weening myself to my other accounts :P
Show threadYour's Truly Sep 21, 2018
@mwlucas in reality i should just export my data from that account and import it here but hey ive got a little while
Show threadalt for @[email protected]Sep 21, 2018

@somarasu I appreciate a person what knows his limits.

And I'm confident you could learn. I mean, if Mr English Degree here can do it, anyone can.

Show threadSullySep 21, 2018
@mwlucas I did a CCNA a decade ago through work and it remains ons of the most useful things I ever learnt.
Show threaded(1) conferenceSep 21, 2018

@mwlucas CIDR and IPv4 are fine. But 128-bit math IPv6 masking/prefixing get a bit taxing on the brain. ;-)

Speaking of which, CIDR day is on Monday. Any plans to celebrate?

https://twitter.com/mwlauthor/status/1008673944101060613

@[email protected] #ratified🐀 (@mwlauthor) on X

Classless routing became an RFC on 24 Sept 1993. I hereby declare 24 Sept #CIDRDay. A quarter-century since classful routing was a thing. Celebrate by having a cider, and booting anyone who still talks about Class C addresses.

X (formerly Twitter)
Show threadthe Hearth Sep 21, 2018
@mwlucas Is there any simple way to explain to a non-networking electrical engineer what exactly this means? I'm curious!
Show threadalt for @[email protected]Sep 21, 2018

@Felthry As you're an electrical engineer, so I'll assume you know binary math.

An IPv4 address is a 32-bit number. Under classful routing, you can only divide networks by size on 8 bit boundaries: 8-bit, 16-bit, 24-bit. Most networks are 256 addresses, even if they only need 3 hosts.

With CIDR, you can divide networks on any bit you like.

Show threadthe Hearth Sep 21, 2018
@mwlucas That makes sense. Well, it doesn't make sense why they would design it that way but I guess they probably had a reason.
Show threadalt for @[email protected]Sep 21, 2018
@Felthry The reason's easy. "The Internet's never going to go anywhere. We'll never have more than, say, three hundred hosts on it."
Show threadalt for @[email protected]Sep 21, 2018
@Felthry there's a decent explanation at https://www.digitalocean.com/community/tutorials/understanding-ip-addresses-subnets-and-cidr-notation-for-networking, or I have a writeup in "Networking for Systems Administrators," https://mwl.io/nonfiction/networking#n4sa
Understanding IP Addresses, Subnets, and CIDR Notation for Networking | DigitalOcean

IP addresses, networks, submasks, and CIDR notation can be difficult concepts to understand. In this guide, we will cover some of the basic ideas behind how these systems work together to allow computers to communicate over the internet.

Show threadxpacSep 21, 2018
@mwlucas drinking Cider!
In memories of all the poor souls lost to true networking, because they were still taugt network classes in university etc...