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Author Topic: ZyXEL VMG1312-B10A Modems - QoS Support  (Read 1364 times)

Weaver

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ZyXEL VMG1312-B10A Modems - QoS Support
« on: May 17, 2018, 04:11:09 AM »

In this modem, does the QoS functionality described in the web ui make any sense or even apply if the the device is in modem-only ‘bridged’ mode? It would have to snoop on the PPP and PPPoE packets’ payload / contents then, to be able to apply ethernet L2 QoS and or L3 IP QoS-based functions?

The ISP AA applies some customisation to the config which is called QoS, but I don't know if this is just a mistake, an unintended commonality with the settings they use when they are programming the devices for shipping as routers not modems.
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neil

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #1 on: December 08, 2020, 06:07:55 PM »

I have the same question
is qos of any use? when modem is in bridge mode?
and even when it is not
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burakkucat

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #2 on: December 08, 2020, 06:21:57 PM »

It's an interesting question and one that I am unable to answer.

All I can say is that with my VMG1312-B10A, deployed as a modem/router/etc, I have configured QoS with the upstream traffic priority assigned by the packet length.
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Weaver

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #3 on: December 08, 2020, 11:58:22 PM »

It would certainly be very good to be able to prioritise acks and take heed of L2- and L3-PDU marking by applications so that flows are mapped to the correct queues.
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tubaman

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #4 on: December 09, 2020, 08:46:09 AM »

Perhaps I'm being too simplistic, but I wouldn't expect QOS settings in a pure modem as it would have to inspect each data packet to apply them, and that is a router's job.
 :)
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Alex Atkin UK

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #5 on: December 09, 2020, 11:37:02 AM »

I'd imagine the best you can do is like the HG612 default config, reserve some upload capacity to reduce buffer bloat.
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neil

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #6 on: December 10, 2020, 12:34:47 AM »

It's an interesting question and one that I am unable to answer.

All I can say is that with my VMG1312-B10A, deployed as a modem/router/etc, I have configured QoS with the upstream traffic priority assigned by the packet length.
these settings going to make any difference or not? Is it only for incoming traffic or outgoing too?
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hopkins35

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #7 on: December 10, 2020, 03:43:54 PM »

My two VMG1312-B10A are in bridge mode and I set the QoS on both as per A&A's instructions here https://support.aa.net.uk/VMG1312-B10A:_QoS and when testing with a large file upload, the modems registered a 'drop rate' figure on the QoS monitor page and A&A's Firebrick graphs showed reduced latency compared to QoS off. So in my experience simple QoS works for uploads in bridge mode
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neil

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #8 on: December 10, 2020, 06:05:23 PM »

My two VMG1312-B10A are in bridge mode and I set the QoS on both as per A&A's instructions here https://support.aa.net.uk/VMG1312-B10A:_QoS and when testing with a large file upload, the modems registered a 'drop rate' figure on the QoS monitor page and A&A's Firebrick graphs showed reduced latency compared to QoS off. So in my experience simple QoS works for uploads in bridge mode

that's nice but i don't have any such settings to enable QoS based on packet size
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Alex Atkin UK

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #9 on: December 11, 2020, 02:31:16 AM »

I'd expect that throttling the upload on your router would work just as well, the trick is simply to avoid buffering in the modem by making sure upload never exceeds the upstream capacity.
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hopkins35

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #10 on: December 11, 2020, 07:06:48 AM »

I'd expect that throttling the upload on your router would work just as well, the trick is simply to avoid buffering in the modem by making sure upload never exceeds the upstream capacity.

Yes but the key with setting QoS on the modem is that it knows your sync rate and can set the throttling accordingly, anything done on the router would need to be manually set or scripted
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Alex Atkin UK

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #11 on: December 11, 2020, 07:39:13 AM »

Yes but the key with setting QoS on the modem is that it knows your sync rate and can set the throttling accordingly, anything done on the router would need to be manually set or scripted

In theory yes, but in practice I do not believe it works that way as line rate doesn't necessarily correlate with real-world throughput.
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meritez

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #12 on: December 11, 2020, 09:27:58 AM »

that's nice but i don't have any such settings to enable QoS based on packet size

Interesting, which firmware version?
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Weaver

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #13 on: December 11, 2020, 11:50:08 AM »

I have a parameter which I call ‘modem load factor’ (MLF), discussed in older threads, which is used in the equation

    firebrick_egress_rate_into_modem = modem_sync_rate * protocol_efficiciency * modem_load_factor

where protocol_efficiency = 0.884434, and modem_load_factor = 0.95 so roughly 5% of IP upstream rate is still available spare. I have tried different values of MLF but 0.95 seems as good as anything.
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neil

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Re: ZyXEL VMG1312-B10A Modems - QoS Support
« Reply #14 on: December 11, 2020, 12:41:30 PM »

Interesting, which firmware version?
I am not from UK
In VDSL modem QoS settings are like this as shown in dlink maunal
ftp://ftp.d-link.co.za/DSL/DSL-G225/Telkom/Setup%20Guides/VDSL%20Internet%20Connection%20DSL-G225.pdf
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