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How (and why) to Ramble on your goat sideways

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Old 06-22-2016, 11:46 AM
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In general, if you're interviewing for a tech position, don't you expect at least a few "gotcha" questions to see if you're faking it? In my last interview, in the midst of telling them about my hobbies, one of the interviewers suddenly asked me what NAT stood for and basically how it worked.
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Old 06-22-2016, 11:48 AM
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Originally Posted by Erat
What the hell is a subnet mask?
Its like the zip code on an package address label, it tells the postman what town to send your fleshlight to before they start looking at the actual street address.
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Old 06-22-2016, 11:51 AM
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Originally Posted by mgeoffriau
In general, if you're interviewing for a tech position, don't you expect at least a few "gotcha" questions to see if you're faking it? In my last interview, in the midst of telling them about my hobbies, one of the interviewers suddenly asked me what NAT stood for and basically how it worked.
Exactly. I do the same.

If I ask a person "What is ASI," I don't expect them to be able to recite for me every little technical detail about how the encapsulation works, how MPEG works, how the streams are formatted and multiplexed, etc. I do expect them to say something like "It's a transport mechanism which is compatible with SDI at the physical layer, so it can use the same DAs and routers, but unlike SDI it allows you to carry multiple streams of MPEG-compressed video & audio over a single link. Usually, you use it to send the encoded airchain signal out to the transmitter, or to bring signals into the station from a satellite or ENG receiver."
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Old 06-22-2016, 11:52 AM
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Originally Posted by mgeoffriau
In general, if you're interviewing for a tech position, don't you expect at least a few "gotcha" questions to see if you're faking it? In my last interview, in the midst of telling them about my hobbies, one of the interviewers suddenly asked me what NAT stood for and basically how it worked.
Eh, I see what you are saying.

I guess it depends on what the specifics of the position actually are. If you were interviewing as a Network Engineer or a position where you would be dealing with the nuts and bolts of internal routing then yeah, the response would need to be significantly more detailed.
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Old 06-22-2016, 11:53 AM
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Originally Posted by EO2K
Its like the zip code on an package address label, it tells the postman what town to send your fleshlight to before they start looking at the actual street address.
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Old 06-22-2016, 11:57 AM
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Originally Posted by Girz0r
My other response was going to be "Ask @hustler, he's all about subs and masks" but I figured I would make it more relevant to the conversation at hand.
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Old 06-22-2016, 01:14 PM
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Originally Posted by EO2K
I mean, what were you reasonably expecting as an answer?

I would expect something super generic like "a subnet mask helps the TCP protocol determine if a host is on the local or a remote subnet" but no way would I expect anyone to sit down and start breaking out the binary.
Actually a netmask is more of an IP layer thing than a TCP one.

Did you know that there's a perfect hash to identify IPv4 net masks? It turns out that if you take the 32 bit representation and mod it by 37 then all 33 valid net masks will fall into different buckets.

--Ian
(wrote software for 14 years at Cisco, now 5 years at Arista Networks )
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Old 06-22-2016, 01:27 PM
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Originally Posted by codrus
Actually a netmask is more of an IP layer thing than a TCP one.

Did you know that there's a perfect hash to identify IPv4 net masks? It turns out that if you take the 32 bit representation and mod it by 37 then all 33 valid net masks will fall into different buckets.

--Ian
(wrote software for 14 years at Cisco, now 5 years at Arista Networks )
So you want to come over to my house and setup my network? I can pay you in kittens.
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Old 06-22-2016, 01:57 PM
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Originally Posted by codrus
Actually a netmask is more of an IP layer thing than a TCP one.
To be fair I probably should have said TCP/IP? :P

Originally Posted by codrus
Did you know that there's a perfect hash to identify IPv4 net masks? It turns out that if you take the 32 bit representation and mod it by 37 then all 33 valid net masks will fall into different buckets.
See? Its always one of you guys (usually its Joe)

Originally Posted by shuiend
So you want to come over to my house and setup my network? I can pay you in kittens.
Wifi is a fad, I recommend physical ethernet for everything. Start drilling.
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Old 06-22-2016, 02:31 PM
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Originally Posted by EO2K
Wifi is a fad, I recommend physical ethernet for everything. Start drilling.
While I wouldn't say wifi is a fad, I actually do recommend physical ethernet for anything that isn't portable and battery-powered.
Wired ethernet is so much more reliable than wifi.

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Old 06-22-2016, 02:32 PM
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That grey cable is making me physically ill.

But I can ignore it because you didn't loose the dustcaps for the GBIC ports
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Old 06-22-2016, 02:33 PM
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Originally Posted by shuiend
So you want to come over to my house and setup my network? I can pay you in kittens.
See earlier comments about consulting rates. If you paid me in kittens, I'd be a crazy cat lady in like 2 minutes.

--Ian
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Old 06-22-2016, 02:36 PM
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Originally Posted by codrus
See earlier comments about consulting rates. If you paid me in kittens, I'd be a crazy cat lady in like 2 minutes.
I mean, what's the current market value of kittens?
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Old 06-22-2016, 02:39 PM
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Originally Posted by EO2K
That grey cable is making me physically ill.

But I can ignore it because you didn't loose the dustcaps for the GBIC ports
Those are SFPs, not GBICs.

Are your talking about the gray cable that goes up (to the router) or the one that goes down (the one that was plugged into the laptop I was using to configure stuff)?

--Ian
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Old 06-22-2016, 02:44 PM
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Originally Posted by EO2K
Wifi is a fad, I recommend physical ethernet for everything. Start drilling.
I actually have wires running to my room from the router. Everyone who is not me can deal with shitty wifi in my house, I don't play that **** on my desktop and my Roku3.

Originally Posted by codrus
See earlier comments about consulting rates. If you paid me in kittens, I'd be a crazy cat lady in like 2 minutes.

--Ian
I have plenty of cats. We can make this happen.
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Old 06-22-2016, 02:58 PM
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Originally Posted by codrus
Those are SFPs, not GBICs.
Yes, GBIC generally goes into SFP port. You can tell how often I get into these things.

Originally Posted by codrus
Are your talking about the gray cable that goes up (to the router) or the one that goes down (the one that was plugged into the laptop I was using to configure stuff)?
Yes.

What, are you too good for a serial cable? Sorry, I have a metric buttload of aging Cisco infrastructure stuff on site that's all serial console cable. (I'm probably just jealous because I have no formal training with IOS and not enough regular use to be any kind of proficient.)

Speaking of web interfaces, were you still with Cisco when they acquired Meraki? Why did it take so god damn long for Cisco to integrate Merakis web interface stuff? Seriously, the management tools are amazing. I just wrapped up an infrastructure project where we replaced about 150 ancient Cisco Aironet APs with Aerohive hardware. The interface is ok, but what I've seen of Meraki is so much better. :(
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Old 06-22-2016, 03:36 PM
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Meraki is fantastic. I'd love to test out their MDM stuff as well, but we have too much sunk cost in our MobileIron MDM.
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Old 06-22-2016, 03:51 PM
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Originally Posted by EO2K
Yes, GBIC generally goes into SFP port. You can tell how often I get into these things.
Technically, SFP is a subset of GBIC. The original GBIC was about 3x the size of a modern SFP, which is colloquially called mini-GBIC. Most GBICs used SC connectors, as opposed to the LC which is now standard.



We still have several ****-kilograms of SC / GBIC in use here, mostly in our big-goomba 6500 core switches. The newer stuff is all SFP / LC.
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Old 06-22-2016, 04:46 PM
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Originally Posted by EO2K
What, are you too good for a serial cable? Sorry, I have a metric buttload of aging Cisco infrastructure stuff on site that's all serial console cable. (I'm probably just jealous because I have no formal training with IOS and not enough regular use to be any kind of proficient.)

Speaking of web interfaces, were you still with Cisco when they acquired Meraki? Why did it take so god damn long for Cisco to integrate Merakis web interface stuff? Seriously, the management tools are amazing. I just wrapped up an infrastructure project where we replaced about 150 ancient Cisco Aironet APs with Aerohive hardware. The interface is ok, but what I've seen of Meraki is so much better. :(
There's no serial console on a $200 netgear switch, it's all ethernet based.

I left Cisco in 2011, the Meraki acquisition appears to have been in 2012. As for why it took so long -- Cisco's software development is broken. Everything is forked, even though everything nominally runs IOS (or NXOS or whatever else) and the first 4 to 6 numbers in the version string may be the same, you should really think of every different product they make as running its own unique software image on its own ClearCase branch, with bug fixes taking months if not years to go from one place to another if indeed they ever happen at all.

I worked on the Catalyst 4000/4500 platform software. If you've ever used a 4500 to do hardware layer 3 packet forwarding, you've used my code.

--Ian
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Old 06-22-2016, 06:23 PM
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Originally Posted by codrus
I worked on the Catalyst 4000/4500 platform software. If you've ever used a 4500 to do hardware layer 3 packet forwarding, you've used my code.
4000/4500 you say?



And it talks to another one on the other side of the building. Sure is a great big heavy sumbitch.
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