Rick Guyton Posted March 17, 2017 Report Posted March 17, 2017 Has anyone else noticed that call quality over TCP is noticeably degraded? In diagnosing an un-related issue I swapped a phone over to TCP and though it fixed the issue I was having, I noticed calls on those phones seemed noticeably degraded. I understand that there's more overhead with TCP. But these guys were on a 100/100 meg connection and using less than 10%...Just curious if anyone else has seen this.
Karl Stallknecht Posted March 17, 2017 Report Posted March 17, 2017 Specifically what do you mean by call quality? As in the call itself was cutting in and out and made it difficult to understand, or it just didn't sound as crisp and clear?
Rick Guyton Posted March 17, 2017 Author Report Posted March 17, 2017 No cutting out, you could understand perfectly, just wasn't crisp and clear. Like maybe the HD audio codecs weren't working. I know your a Polycom guy Karl, this was on a yealink. Man, if this kind of crazyness keeps going I might try switching to polycoms...
Administrators Darren Schreiber Posted March 17, 2017 Administrators Report Posted March 17, 2017 Switching to TCP just changes signaling. If you were using UDP, it didn't work well, you switched to TCP and your "signaling" issues went away but you now have audio issues, you've actually proven that the internet or network IS the problem.TCP covers up connectivity problems, which is why we don't like it. UDP has no error correction built-in, so errors and unreliable links become problematic. TCP corrects errors on it's own, but you can't use it for audio because it adds delay. So audio still remains UDP. Thus, if TCP "fixes" your original issue, then really TCP likely just "covered up" your original issue and now UDP is still used for audio but is still having the same issue.
Rick Guyton Posted March 17, 2017 Author Report Posted March 17, 2017 Thanks Darren, this client is on Comcast and in an area I'm not familiar with. I wouldn't doubt it actually.
Administrators Darren Schreiber Posted March 17, 2017 Administrators Report Posted March 17, 2017 No problem, if it is Comcast you should be experiencing it on all phones, unless it's a local LAN issue.There are some other things to try. You indeed could try switching codecs. Believe it or not sometimes audio sounds funky when it gets "upsampled" to HD but is actually a regular PSTN call on PCMU.
Karl Stallknecht Posted March 17, 2017 Report Posted March 17, 2017 Nothing surprises me about Comcast ;-) It's definitely better in some places than others though.I was about to say Verizon FiOS is like heaven when we have a customer with it, but their new "Quantum" routers have serious issues with SIP signaling where random phones don't ring, or phones keep ringing after calls are answered. We immediately replace the Quantum routers with something else and all of the problems go away. We've literally never gotten any other complaint from a FiOS customer (and now we get none because we know to switch the router out before setting them up).My fear is that Comcast will start doing the same thing. So far so good with their issued modem/router units (knock on wood), but the huge problem with Comcast is that if you have a static IP, you HAVE to use their modem/router and there is no way around it. What happens when their routers start causing VoIP issues but the customer has to have a static IP? Then what?And if you're wondering why Comcast requires you to use their modem/router when you have static IPs, it has to do with a combination of how they handle subnetting and their specific implementation of RIP. Basically comes down to how they have decided to ensure you aren't announcing the wrong IPs.And no, bridge mode might not be the solution either because their bridge mode is still doing Layer 3 functionality.
Jesse Howard Posted March 17, 2017 Report Posted March 17, 2017 We actually believe Comcast was de-prioritizing UDP SIP/RTP for a customer (different voice platform) since by sending the traffic over a GRE tunnel between the customer router and our data center where they couldn't inspect it and it resolved their signaling and audio issues. Using SRTP didn't really solve anything because the headers are still available for identifying traffic type but the tunnel made a difference.Fairly certain that is illegal (continue to just say NO to internet fast lanes!) so good luck getting them to admit to it but something to consider when using ISPs who offer the same services on their own Network.
Administrators Darren Schreiber Posted March 17, 2017 Administrators Report Posted March 17, 2017 Funny, we got that same complaint from a Comcast customer in Virginia recently. Seems like a trend.
Karl Stallknecht Posted March 17, 2017 Report Posted March 17, 2017 Comcast in Virginia is *mostly* a nightmare...surprisingly it's much better in D.C. and Maryland.
Administrators Darren Schreiber Posted March 17, 2017 Administrators Report Posted March 17, 2017 Something to keep in mind... "Comcast" is really American Cable Systems. Which became Comcast in 1969. Then they bought Group W Cable in 1986. Then Storer Communications in 1985. Then it bought Maclean-Hunter's US division. Then it started rolling out internet via the "@Home" network (anyone remember this?). This was partially via a company named "Excite", who went bankrupt, and Comcast bought their assets.Then they bought Prime Communications. and some VeriSign stock. and MediaOne (via a trade with AT&T). Also they bought AT&T Broadband. and Patriot Media in 2007.shall I go on?If you think during each of these mergers, they walked in and within 90 days ripped & replaced all the customer equipment, billing systems, routers, switches, fiber cables, etc. with a nice unified system... Wellllll hehehe ummm In reality they're JUST getting to that point now with just their portal and ticketing systems (within the past couple years). They still operate the territories somewhat separately.Why am I saying all this? My guess is they have different equipment and programming in each region.Hence the weird, inconsistent network results.There is no "Comcast" there's just "merger mess with a nice name."
Karl Stallknecht Posted March 17, 2017 Report Posted March 17, 2017 I guess that explains why one time we asked for a customer's Comcast bill and it didn't look like any Comcast bill I had ever seen in my life before lol...
Logicwrath Posted March 17, 2017 Report Posted March 17, 2017 Did you also encrypt the traffic with IPSec or just setup a simple GRE tunnel without encryption?I suspect Comcast is willing to do stuff like this. There is probably already some precedent involving Netflix. This is why Netflix setup https://fast.com/.
Logicwrath Posted March 17, 2017 Report Posted March 17, 2017 Did you also encrypt the traffic with IPSec or just setup a simple GRE tunnel without encryption?I suspect Comcast is willing to do stuff like this. There is probably already some precedent involving Netflix. This is why Netflix setup https://fast.com/.
Logicwrath Posted March 17, 2017 Report Posted March 17, 2017 I was recently told from an insider that Comcast runs their "nodes" at 87-92% utilization and that they intermingle residential and business accounts.I believe WOW runs closer to 65% utilization and does not intermingle business and residential. I don't have all the details or a complete understand on how this stuff works but I figured I would share it anyways.
Jesse Howard Posted March 17, 2017 Report Posted March 17, 2017 @Logicwrath - yes. Sorry if that was confusing. We haven't really ever set it up without IPSec because encryption is usually the point.
Karl Stallknecht Posted March 17, 2017 Report Posted March 17, 2017 Yea the whole "Comcast Business" thing is a joke. It's the same exact service as residential and all of their sales pitches about getting same day service and such are literally flat out lies.
Administrators Darren Schreiber Posted March 17, 2017 Administrators Report Posted March 17, 2017 It's absolutely not the same service, Karl. It's at least 3x more expensive. ;-)(Oh and you get a nicer looking modem)
Karl Stallknecht Posted March 17, 2017 Report Posted March 17, 2017 My bad, I forgot about all of those added benefits :-)
Guest Posted March 21, 2017 Report Posted March 21, 2017 sorry i'm late to the party - we went through about 30 days of a sh%t storm trying to engineer around Comcast in Nashville. Same issues plus there was noticeable delay on most calls. I'm talking 2-3 seconds like when we used to call overseas in the 80's. Yeah, you remember. We tried everything - including buildng an IPsec tunnel into our office and then routing out. It seemed to fix the issue once Comcast couldn't inspect but was going to be a pain to backhaul all that voice and add complexity. The issue presented itself more often when there were 2 or more concurrent calls. We also got a Comcast SE to admit they throttle RTP for non-Comcast VoIp customers!In the end we removed the VPN tunnel and have aggressively throttled the bandwidth on our router using overthrottling. The Comcast modem is bridged with a static IP so just passes traffic, in theory. We have a QoS policy applied to the voice VLAN and since the throttling never gets anywhere near 75% of the tested capacity of the line (up and down) it seems Comcast's de-prioritization never kicks in. BOO YA COMCAST
Karl Stallknecht Posted March 21, 2017 Report Posted March 21, 2017 Yikes, you make our stories sound like nothing LOL. I would have given up and told the customer to get a T1 :-/ But that's awesome that you were able to get around it!
Logicwrath Posted March 21, 2017 Report Posted March 21, 2017 Is there a way to disable the inspection by enabling SSL on the media like ZRTP or something similar?
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