I think a good test would be to give a prospective candidate a MCU like a 6805 or an 8051 with 128 bytes of RAM and 8K of ROM and have them implement a DTMF synthesizer, interrupt driven button interface, SPI flash aux memory, LCD display and PWM dimmer with zero crossing detection... all in the same program... all running a pseudo RTOS function pointer driven finite state machine. If their first question is “what is a state machine” you show them the door.
Also, take away everything except the specs off the chip and reference materials for the language they are using. No internet code samples. Yeah..... love to see them do it without code samples.... Maybe start them with some assembly or pure machine code. “What’s an OP code”? Hit the eject button. Now-a-days, code writers seem like doctors that never had to take gross anatomy. Of course this is just an opinion and is most likely out of touch with the real world and 25 years out of date. I greatly admire the extremely powerful stuff you can create these days with modern tools and libraries, but when my kids who are taking engineering classes come to me, I still show them a thing or two about indexing an array or a bubble sort. From: Ken Hohhof Sent: Sunday, June 07, 2015 1:24 PM To: [email protected] Subject: Re: [AFMUG] ePMP VoIP QoS I’ve got to agree with George on this one. I realize Cambium apparently has 2 separate design teams (3 if they still have the one in Ashburton), and likely the ePMP firmware team is somewhere else in the world. But why do they always have to re-invent the wheel, then have customers tell them they already had a product that wasn’t broke so unless the new way is leaps and bounds better, please make it the same. And even if the firmware is written elsewhere, isn’t that what Product Managers and Design Specs are for? This is one of the problems I see a lot when software is designed by 20 year olds in India, Asia or Eastern Europe (and even Redmond and Silicon Valley) who have read a lot of RFCs and other standards but don’t have much real world experience. Also I think that’s how you get a GUI that makes over 100 separate resource requests, you get young coders who have learned that way and are clueless about efficient coding methods for embedded firmware. Maybe they need to hire some greybeards from the arcade game business, people who knew how to run PacMan on a 6507. Or some of the people laid off by Disney and made to train their H1B visa replacements. Or people like Forrest, doesn’t his stuff run on something like a Z80? As far as telling a customer you aren’t going to use a non standards based solution to fix the crappy device they bought, good luck with that. Customers don’t care about standards, except the one that says “the customer is always right”. Seen at Jimmy John’s: “The Customer Is Usually Right” From: Faisal Imtiaz Sent: Sunday, June 07, 2015 1:57 PM To: [email protected] Subject: Re: [AFMUG] ePMP VoIP QoS Please don't take this personal, just take it as constructive criticism.... >>Trying to get the guys to remember to add a bunch of rules in a radio >>probably won't happen. I think you may have a QC / installation process issue (aka provisioning), which you are trying to compensate for. >>Maybe I'm a nazi when it comes to the network, but.. don't touch the network >>and I won't have to kill you. Instead of taking this stance, I suggest you look into how to make changes without someone screwing up something else by mistake. (hint.. changing stuff via scripts is one way to do this). >>>It took them a YEAR to fix the stuff we showed them was broken in their >>>software! But no, we're the asshole to the customer which forces us to hack >>>shit to make it work, and then it's still not up to the customer's >>>expectations. Why are you/your customers insisting on using GrandStream phone ? Just another suggestion:- We would much rather run a 'standard' based network, and not customize these types of settings on the Radios.. If we ran into this type of a situation, we would offer a managed router service (free or nominal charge), and or use a mikrotik router as a dmarc on the customer prem, and do all the funny business customization on that. Regards Faisal Imtiaz Snappy Internet & Telecom 7266 SW 48 Street Miami, FL 33155 Tel: 305 663 5518 x 232 Help-desk: (305)663-5518 Option 2 or Email: [email protected] -------------------------------------------------------------------------------- From: "George Skorup" <[email protected]> To: [email protected] Sent: Sunday, June 7, 2015 2:24:36 PM Subject: Re: [AFMUG] ePMP VoIP QoS Right. As I said, I've never had to change any of the DiffServ code points on any Canopy radio. Trying to get the guys to remember to add a bunch of rules in a radio probably won't happen. It's easier for me to tell them to just turn on HP. Maybe I'm a nazi when it comes to the network, but.. don't touch the network and I won't have to kill you. Anyway.. the new Grandstream firmware, how awesome is this.. the SIP QoS default is DSCP 26, which is LP on Canopy. Knowing that, I DO NOT want the guys touching the DiffServ code points in the radios. It's easier to configure the phones with SIP DSCP 12 and RTP DSCP 46. To accommodate the stupid/broken devices, I already have other rules on the network that prioritizes SIP as 12 and RTP as 46. I like standards. OK, my standards. On 6/7/2015 12:59 PM, Josh Luthman wrote: Works on Canopy, though. Josh Luthman Office: 937-552-2340 Direct: 937-552-2343 1100 Wayne St Suite 1337 Troy, OH 45373 On Sun, Jun 7, 2015 at 1:56 PM, Mike Hammett <[email protected]> wrote: Having only half listened to the thread, it sounds like broken Grandstream VoIP is broke on ePMP. ----- Mike Hammett Intelligent Computing Solutions http://www.ics-il.com Midwest Internet Exchange http://www.midwest-ix.com -------------------------------------------------------------------------- From: "Josh Luthman" <[email protected]> To: [email protected] Sent: Sunday, June 7, 2015 12:54:29 PM Subject: Re: [AFMUG] ePMP VoIP QoS For this use case (QoS on VoIP): Cambium Canopy works Cambium ePMP does not work Seems that simple to me. Josh Luthman Office: 937-552-2340 Direct: 937-552-2343 1100 Wayne St Suite 1337 Troy, OH 45373 On Sun, Jun 7, 2015 at 11:11 AM, Faisal Imtiaz <[email protected]> wrote: BTW, the latest firmware for GXP 2160 is 1.0.4.23 (did a google search), and the admin manual shows two settings for L3 QOS (one for SIP and one for RTP) EPMP QOS allows you to modify the default settings to over-ride to your taste. If I understand your 'complaint' you are dealing with f**ed up GrandStream Phones, and you want Cambium to Change the Default handling of VOIP QoS to match your needs ? Now that does not make any logical sense... The default setup for QoS Voip on EPMP is perfectly fine for all of the other devices which follow the industry standard of VOIP/Video packet marking. Unless there is something that I am totally missing, I think you are taking out your frustrations with GrandStream on Cambium ! :) Faisal Imtiaz Snappy Internet & Telecom 7266 SW 48 Street Miami, FL 33155 Tel: 305 663 5518 x 232 Help-desk: (305)663-5518 Option 2 or Email: [email protected] ----- Original Message ----- > From: "George Skorup" <[email protected]> > To: [email protected] > Sent: Sunday, June 7, 2015 3:06:27 AM > Subject: Re: [AFMUG] ePMP VoIP QoS > > The 1.0.4.17 firmware for the GXP phones (we have mostly 2160s and some > 30s and 40s) cannot be downgraded since it contains a security fix. I > have a couple phones that are now fk'n stuck on that because of it. > We're running an internal engineering build on some phones with fixes > for their screwed up SIP message handling and corrupt outgoing messages. > Some phones we have not upgraded from 1.0.3.9 because it mostly works. > None of those firmwares allows separate SIP and RTP QOS. We're doing > testing and validation of 1.0.4.23 with our switch vendor currently, > which does do the split QoS. About half of the bug fixes listed in the > .21/.23 release notes were ours. Just have to wait and see what other > shit is broken now. > > But besides all that, I have other phones and ATAs (both Grandstream and > not) that refuse to send SIP with anything other than DSCP12, even when > it's configurable. I don't really care if SIP is sent with AF and RTP as > EF, that's perfectly acceptable. RTP should be higher priority than SIP > anyway. Standard DiffServ config supports this just fine. So as far as > the network is concerned, I have to support AF and EF, and I'm fine with > that. All I was saying is that Cambium should do this out of the box on > ePMP if you turn on VoIP priority. This is what happens on Canopy when > you turn on HP on an SM, both DSCP12 and 46 end up in the HP channel. > > On 6/7/2015 1:11 AM, Josh Reynolds wrote: > > I don't know what grandstream devices you are looking at, but 21xx series > > and the other Linux and android based phones don't have that issue. > > Neither does the asterisk based UCMs, such as the 6104. Screenshots > > attached. > > > > On Jun 6, 2015 8:17 PM, George Skorup <[email protected]> wrote: > >> I disagree. This is exactly what Canopy does. DSCP12/AF is sent over the > >> HP channel. Look at the default DiffServ table and see for yourself. > >> Many managed switches are set up exactly the same way, except they have > >> more queues, and Canopy only has MIR and HP. Well, there's LP CIR, but > >> lets not get into that. ePMP just has "priority" which I assume means > >> priority over everything else. > >> > >> I need a way to correct stupid manufacturer's mistakes (Grandstream > >> being the worst offender). Lots of their devices ALWAYS send SIP packets > >> as DSCP12 and this CANNOT be changed. Or the other one I mentioned, the > >> GXP phones have one DSCP setting and this changes both SIP and RTP. I'm > >> disgusted with their stupidity, but unfortunately it has to be supported > >> because those devices aren't going away. > >> > >> It's totally doable and Cambium could add it by default, saving me time > >> configuring every radio with it. Or just make DiffServ on ePMP > >> work/configure like Canopy. > >> > >> I don't care what's wrong or right. I care about shit working right now > >> and customers not being pissy. > >> > >> So the burden falls on the network as usual. It's always our fault. > >> Sometimes I just don't know how I haven't murdered people. If I drank, > >> it would probably happen. And I'm finding myself agreeing with that one > >> guy Steve every other day now. Stupidity has no limit. > >> > >> On 6/6/2015 10:31 PM, Faisal Imtiaz wrote: > >>>> Yo Cambium, you need to add DSCP 12 (Assured Forwarding) in addition to > >>>> DSCP 46 (Expedited Forwarding) to the default VoIP priority > >>>> configuration. > >>> That would be a mistake and the wrong thing to do. > >>> > >>>> We're finding more devices sending SIP packets as AF and > >>>> RTP as EF. > >>> When a device is mis-configured, why should the burden of dealing with > >>> that mis-configurtion as a default fall on another device > >>> > >>> There is plenty of flexibility to override the wrong setup of a device, > >>> if that is they way you want to correct it in your radios... > >>> (Which by all standards would be the wrong way to fix it...but more power > >>> to you). > >>> > >>> Two wrongs don't make a right.. > >>> > >>> > >>> Regards. > >>> > >>> > >>> Faisal Imtiaz > >>> Snappy Internet & Telecom > >>> 7266 SW 48 Street > >>> Miami, FL 33155 > >>> Tel: 305 663 5518 x 232 > >>> > >>> Help-desk: (305)663-5518 Option 2 or Email: [email protected] > >>> > >>> ----- Original Message ----- > >>>> From: "George Skorup" <[email protected]> > >>>> To: [email protected] > >>>> Sent: Saturday, June 6, 2015 10:27:05 PM > >>>> Subject: [AFMUG] ePMP VoIP QoS > >>>> > >>>> Yo Cambium, you need to add DSCP 12 (Assured Forwarding) in addition to > >>>> DSCP 46 (Expedited Forwarding) to the default VoIP priority > >>>> configuration. We're finding more devices sending SIP packets as AF and > >>>> RTP as EF. AF isn't prioritized and out-of-band signaling (prompts, etc) > >>>> are sent as SIP messages so sometimes these are getting dropped, not to > >>>> mention registrations, invites, etc. And more devices are stupid (mostly > >>>> Grandstream), they only let you set ONE priority value for the entire > >>>> device. These are coming default as DSCP12/AF. I've tried to get > >>>> everyone to change this to 46, but they don't remember. > >>>> > >>>> Or just apply the whole Canopy DiffServ table. We've never had to change > >>>> any of those code points. Turn HP on, it just works. > >>>> > >
