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Author Topic: VLAN ID Priority (0-7) or 802.1p  (Read 8480 times)

Zoe

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VLAN ID Priority (0-7) or 802.1p
« on: August 06, 2017, 03:34:25 PM »

Hi  :)

I have Fibre (VDSL) 38/10 and My ISP is Talk Talk.
The modem router they sent me in June was a Dlink DSL-3782.
But after realising I couldn't change the DNS to Google I bought my own Netgear D6400.

Before setting up my Netgear D6400 I took screen shots and notes of the settings in the Talk Talk supplied Dlink DSL-3782.
Note: There was no mention or setting for 802.1p or Priority (0-7)
Only something in Settings>>Internet .. WAN SETTINGS. There was something called...
PTM VC Setting
Service [ 1 ] Could this be the same thing as Priority (0-7)?
Enable Virtual Circuit [ Enabled ]
Vlan ID [ 101 ]
I was going to post a screen shot but I couldn't figure out how to do it.
Then I searched the Talk Talk forum to make sure I had all the FTTC (VDSL) settings I might need.
Someone said the VLAN ID Priority should be set to 1.
This again made me think of the Service Setting of 1 in the Talk Talk router.

The day came to set up my Netgear D6400 and I used the Netgear Wizard.
Things seemed to be going ok when it asked me to update the firmware. Just as the firmware update started. I noticed I had no internet. Eventually I had to reboot the router and start again. When I started again I realised the Wizard had actually finished it's job. It just hadn't shown me that before asking me to update the firmware. Thank god my new router was ok the firmware update had failed completely. Maybe my internet had gone down before it had fully downloaded.
Anyway... With my laptop connected to the router again. The internet did NOT feel stable/right. And then I noticed that the Netgear Wizard had set the VLAN ID Priority to 2.
So I changed the VLAN ID Priority to 1. And suddenly my internet felt stable/right. I then updated the firmware again and all was well. Happy Ending!

Trouble Is...
Every now and again the question of Priority (0-7) starts to bug me again.
Why is it that every time I Google Priority (0-7) some people very often claim it should be 0.
Many others say it should be 1
Just a few claim it should be 2
There are people claiming 0 or 1 or 2 and posting screen shots all over the internet.
Even on the Talk Talk forum I've found different people saying 0 or 1 or only sometimes 2.
Maybe the setting isn't that important if you get it wrong by just one or something.
My internet works just fine with VLAN ID Priority set to 1.
But the question still bugs me!  :-\
What Is The Truth?

Note: I've tried reading up on Priority (0-7) 802.1p
Call me thick! But I just don't understand what it's all about.
I just want to figure out what the absolute truth is for people on FTTC (VDSL) Talk Talk.

Thanks In Advance!
« Last Edit: August 06, 2017, 04:21:15 PM by Zoe »
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Talk Talk - Faster Fibre: 38/10
Estimated Download Speed 39Mbps to 40Mbps.
Minimum Guaranteed Speed 35Mbps
Actual Sync Speed 31Mbps Down & 8Mbps Up
Modem/Router: Netgear D6400

burakkucat

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Re: VLAN ID Priority (0-7) or 802.1p
« Reply #1 on: August 06, 2017, 07:15:34 PM »

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ejs

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Re: VLAN ID Priority (0-7) or 802.1p
« Reply #2 on: August 06, 2017, 08:12:43 PM »

It's mentioned in section 2.2.3 of BT SIN 498.

Presumably the router can set the priority marking on upstream traffic, SIN 498 describes how the Openreach modem would use the priority. Beyond that it may depend of what if anything the ISP does with the priority marking. It's also not clear what purpose marking everything with the same priority value could serve.
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kitz

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Re: VLAN ID Priority (0-7) or 802.1p
« Reply #3 on: August 06, 2017, 08:29:18 PM »

When I first got my Zyxel, very few people had VDSL modem routers - practically everyone used the Openreach supplied modems and there was a distinct lack of settings available for setting up your own modem anywhere which is why I did this which to be perfectly honest was partially guess work, but it worked fine using [2].

It was about a year later when I was doing some beta-testing with TPlink that they asked if I knew the settings and 2 seemed to work OK and those are what they used for their early quick set-up.  About a month or so later they were contacted by a TalkTalk customer saying it wouldnt work... so they tried [1] which did. Shortly after someone on BT also found they needed to use [1].

[2] continued to work fine for me for nrly 2 yrs - until I got a chromecast which suddenly wouldnt stream content correctly until I changed 2 to 1.
I therefore suspect the priority 1 is needed if you stream IPTV content.  That would explain why some people on BT and TT say either, but some say [1] if they have say TalkTalk TV or BT TV/Sport.

I'm talking off the top of my head here (and memory which may not be 100% correct), but I believe Openreach use different channels for sending different types of data.  [ETA - I see ejs has added the links whilst I was typing]
   
IPTV is given higher priority by Openreach therefore if we set normal data as highest priority when using other services then things start to break.  By using [1] we are allocating Best Effort to normal data and allowing other services such as IPTV priority.
IMHO if you use any of the priority services, then you should use [1] rather than [ 0], but zero should still work.

Hope that makes sense.
« Last Edit: August 06, 2017, 08:34:26 PM by kitz »
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Zoe

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Re: VLAN ID Priority (0-7) or 802.1p
« Reply #4 on: August 07, 2017, 01:25:33 PM »


Hi  :)

Thanks for everyone's help!

When I first got my Zyxel, very few people had VDSL modem routers - practically everyone used the Openreach supplied modems and there was a distinct lack of settings available for setting up your own modem anywhere which is why I did this which to be perfectly honest was partially guess work, but it worked fine using [2].

It was about a year later when I was doing some beta-testing with TPlink that they asked if I knew the settings and 2 seemed to work OK and those are what they used for their early quick set-up.  About a month or so later they were contacted by a TalkTalk customer saying it wouldnt work... so they tried [1] which did. Shortly after someone on BT also found they needed to use [1].

[2] continued to work fine for me for nrly 2 yrs - until I got a chromecast which suddenly wouldnt stream content correctly until I changed 2 to 1.
I therefore suspect the priority 1 is needed if you stream IPTV content.  That would explain why some people on BT and TT say either, but some say [1] if they have say TalkTalk TV or BT TV/Sport.

I'm talking off the top of my head here (and memory which may not be 100% correct), but I believe Openreach use different channels for sending different types of data.  [ETA - I see ejs has added the links whilst I was typing]
   
IPTV is given higher priority by Openreach therefore if we set normal data as highest priority when using other services then things start to break.  By using [1] we are allocating Best Effort to normal data and allowing other services such as IPTV priority.
IMHO if you use any of the priority services, then you should use [1] rather than [ 0], but zero should still work.

Hope that makes sense.


Think I'll definitely be sticking with Priority 1 then.
2 just didn't feel right. Disconnecting and my fibre internet felt like an ageing snail.
I suppose if I ever had any problems I could always try 0
But the most important thing is that my fibre internet works just fine.


Thanks!
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Talk Talk - Faster Fibre: 38/10
Estimated Download Speed 39Mbps to 40Mbps.
Minimum Guaranteed Speed 35Mbps
Actual Sync Speed 31Mbps Down & 8Mbps Up
Modem/Router: Netgear D6400

Chrysalis

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Re: VLAN ID Priority (0-7) or 802.1p
« Reply #5 on: August 07, 2017, 04:17:48 PM »

From the doc ejs linked to I see this

Quote
2.2.3 Upstream priority marking
CPs can (optionally) select the priority for each Ethernet frame via a VLAN PCP field sent into the Openreach modem from CPE.
 PCP = 2 or 3 (4-7 will be treated as 3) → High priority
 PCP = 0 or 1 or unmarked (no VLAN) → Low priority

This would suggest high priority (IPTV) is 2 not 1.

Weird.

For reference I have always used 2.

I have switched now to 1 to see if I observe any differences, as 1 is of course what we should be using (best efforts).

The good news is on the zyxel device i am using switching this is a live change with no sync restart.
« Last Edit: August 07, 2017, 04:25:43 PM by Chrysalis »
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boost

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Re: VLAN ID Priority (0-7) or 802.1p
« Reply #6 on: August 13, 2017, 10:55:25 PM »

High priority = low throughout. Typically policed/shaped. Typically voice calls.

Low priority = high throughput. Everything else. No appreciable rate limit.

No idea if this applies to BT but is common, I'd say.
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Chrysalis

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Re: VLAN ID Priority (0-7) or 802.1p
« Reply #7 on: August 13, 2017, 11:11:12 PM »

This is on openreach so affects all isps that use FTTC.

I have personally not observed any differences which is what I expected because as I understand it openreach have never needed to do policing between the cabinet and exchange as the link never gets saturated.

On GEA test results the policing count is also now visible (can see on plusnet forums) and it always reports zero.
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boost

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Re: VLAN ID Priority (0-7) or 802.1p
« Reply #8 on: August 14, 2017, 08:38:11 AM »

The top end/circuit policed rate has been visible for years on the OGEA test.

I assumed but don't really know there would be a discrete policed rate for expedited traffic that may not be related to that counter.

Been a while since I had any visibility tbh :)
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renluop

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Re: VLAN ID Priority (0-7) or 802.1p
« Reply #9 on: August 14, 2017, 09:08:14 AM »

Completely OT

Hi Zoe! It's over 6 years you haven't been visible. Hope in that time all has been going well for you! :)
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Chrysalis

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Re: VLAN ID Priority (0-7) or 802.1p
« Reply #10 on: August 14, 2017, 09:45:50 AM »

regardless i am leaving mine set to the proper best efforts now as kitz reported issues been fixed plus what boost said is logical
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anything