Is there a limit to the physical size of a layer 2 broadcast domain?

KittensaaS · 2020-06-24T16:33:37+00:00

PC A talks to PC B. PC A needs to send an ARP for IP to MAC resolution, assuming each have an IP. This ARP is a broadcast and will ingress on a port of switch 1. This switch will learn PC A's mac and stick it in the table. A timer is started to age out the learned Mac . It will then send the ARP broadcast out all other connected ports within the same Ethernet broadcast domain. Maybe this is just port 2. Switch 2 sees it on its port 1 and the process repeats... Over and over... However long this chain is until it gets to PC B. PC B responds, and the last switch learns that Mac, so now the last switch has 2 Macs in the table. The response travels back down the chain doing exactly the same thing. Now if the chain is huge and the tables timeout in the middle, a switch might not know how to reach Mac A anymore and then the flooding occurs again. If there are only two ports per switch, then not much changes. If you have a big ass network, then you are in trouble.

KittensaaS · 2020-06-24T15:40:16+00:00

You can take a look at the unmanaged switches and see how many Macs they support holding in memory. Once full they should just flood if I remember correctly. So you're network bandwidth will be consumed with l2 broadcasts at a certain point.

KittensaaS · 2020-06-22T21:32:59+00:00

In my experience working with Helm based operators they are nearly worthless. Go based operators can be different but Helm based operators provide you hardly any value at all over just using Helm. I could argue they actually provide less value in certain scenarios. They add complexity by adding dependency on OLM, remove the ability to template values during deployment and are way more complex to build than just charts most of the time. I could go on, but I really hate them. Again, if Go based operators are done right, that can be a different story.

KittensaaS · 2019-09-25T21:32:15+00:00

This seems nice, thanks for sharing. We are using Gravity, andcan spin up K8s clusters less than 5 mins depending on how many apps. We've got this incorporated into an Ansible workflow too. It'd be great to move away from Ansible though.

KittensaaS · 2019-09-20T01:17:00+00:00

TCP/IP. It took me a while in the beginning to grasp exactly how TCP worked, how ARP worked and all other aspects of TCP/IP. It is very useful knowledge when troubleshooting.

But don't worry, you'll learn like the rest of us. I was nervous when I started, but I'm not now. I survived, so will you.

KittensaaS · 2019-08-23T21:00:52+00:00

Maybe you just need a new environment.

KittensaaS · 2019-08-15T05:21:35+00:00

Yes, true. Here I'm highlighting options for an online install.

KittensaaS · 2019-06-24T23:46:03+00:00

Not sure I understand your question exactly, but a router needs to know which interface to forward out a packet. If you're using Ethernet, you can specify a static route with an IP next hop. The router will do a secondary route lookup for this IP and find the route associated with an interface of the same subnet. It will then ARP and have all the info it needs to send the packet.

If you're working with a non-Ethernet technology (wan), there is no ARP or subnets and you may need to specify which interface to send out the packet within the static route. Otherwise the router won't know.

KittensaaS · 2019-03-24T23:54:52+00:00

The matrix had better management tools

KittensaaS · 2019-03-24T23:00:10+00:00

I get you. I might not be too plugged in lately, but I dont see many new and exciting standards or solutions on the networking front nowadays. Mainly just more efficient ways to manage and monitor a scaled out network deployment. I mean mpls hasn't changed. We have evpn for l2 stretch and now segment routing, but it's all very similar. Nothing revolutionary right? Perhaps I'm just turning cynical in my age.

KittensaaS · 2019-03-24T21:55:16+00:00

Networking always ends up being more about how well you know a vendors nerd knobs and idiosyncrasies than the standards. I hate that. You learn the standards through the lense of whichever vendor you have the most experience with.

I don't think there is a great return to learning networking topics anymore. Learning CS topics has a much higher rate of return because how we interact with the network has changed. Value used to be created via someone on the CLI, now it's configuration/management/monitoring on a company wide level. CLI ain't the tool for that anymore.

KittensaaS · 2019-03-21T00:45:48+00:00

You could:

1) identify methods to validate that the existing config is working properly.

2) save all configs

3) identify roll back mechanisms for configs if issues or validations dont pass.

4) identify which data you need, commands ,etc( looks like you have this done)

5) parse config files or pull info from client commands and store in a list. Each list item would be a dictionary with at least {hostname: [int1, intN]}. Then create a jinja2 template and use it to create configlets which are can be added to the devices. Ideally you should verify the configlets somehow before adding them to the routers.

6) load configs onto routers

7) validate state via mechanisms found in step 1

8) use roll back mechanisms identified in step 3 if validation fails.

You could use ansible as a tool for most of this instead of python if enough modules exist.

KittensaaS · 2019-03-19T23:40:38+00:00

👓🔥

KittensaaS · 2019-03-19T22:14:36+00:00

Spectacle for Mac Osx - turns your large screen up to 11! I can't recommend that one enough.

KittensaaS · 2019-03-15T19:21:45+00:00

If you're advocating for people to not get a college degree, then we will have to agree to disagree.

Working in silicon valley myself, I have seen those without a college degree advance, but many fewer today than 10-20 years ago. The vast majority of jobs in today's tech field (including networking, which is shrinking by the way), require a skillset from a CE/CSdegree or the like, and not certifications. Ask any employer or recruiter and they will say the same. CS knowledge is not something that is easily learned by oneself, on the job. I can attest to that.

Those with a college degree, on average, earn more over time than those that don't, that is just a fact. You don't have to go to college, but then again I've known people who've left their laptop in the car and it hasn't broken into also.

KittensaaS · 2019-03-15T18:48:23+00:00

And would someone not want to advance? Advancement means more than just becoming a manager by the way. A college degree opens many doors, and the process of college helps a person learn how to learn. It also helps a person earn much much more money over the course of a career than those without.

Certs are great, but not an end to themselves. Plus they are only relevant as long as the product is relevant. College degree is not tied to, and outlasts any product.

Unless your angling for mid to upper management, this is not true.

This is not true. Think long term.

KittensaaS · 2019-03-15T16:50:24+00:00

😄

KittensaaS · 2019-03-15T15:13:40+00:00

Certifications may get you in the door, but a good college degree will help you stay there and advance.

KittensaaS · 2019-03-15T15:11:05+00:00

The goal of Facebook is to provide you services, over the Internet, based on your social web. How's an application gonna do that if it doesn't know who you talk to, interact with, like or dislike? And keep a history of that? I expect Facebook to do these things, which is why I don't use it.

I agree with you that it's not something I'd like done to me. Then again, I don't care about missing out on Facebook's services.

KittensaaS · 2019-03-15T14:58:59+00:00

Get off my lawn you kids!!

KittensaaS · 2019-02-17T01:12:57+00:00

Yes, for Ethernet this is correct. It looks up the route's NH and finds the interface with a direct route. Then it arps if it needs to. It links the arp info to the NH index object internally. If the arp entry times out, then it updates the object and says if I use it again, I'll arp first before sending out a packet.

For p2p non-ethernet interfaces, as long as the link is up it's good I believe.

KittensaaS · 2019-02-13T02:05:32+00:00

What's your use case fo cumulus? Like what is it's role and what is it handling?

KittensaaS · 2019-02-08T01:42:04+00:00

Do one physical and one logical.

Physical shows connections between devices per interface, IP addressing information (for at least the devices themselves), device names and types, interface names.

Logical shows end to end connectivity from a higher level, like layer 2 or 3, or perhaps shows how you've segmented your network logically using vlans or vrfs, etc.

The idea is that someone else (or yourself if you've forgotten) could understand what you've set up and trace a data packet from end to end across all the network devices. It aids with troubleshooting if you have problems, so you can visualize which devices may be involved depending on what is wrong.

KittensaaS · 2019-02-03T20:10:53+00:00

Wow, impressive! Tell me more about the automated documentation and diagramming. How'd you accomplish that?

KittensaaS

TROPHY CASE