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Author Topic: DLM put me back on fast path after 4 months  (Read 3791 times)

Interceptor121

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Re: DLM put me back on fast path after 4 months
« Reply #15 on: August 05, 2016, 06:03:51 PM »

Not necessarily what exactly?
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NewtronStar

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Re: DLM put me back on fast path after 4 months
« Reply #16 on: August 05, 2016, 06:36:01 PM »

Have two sets of R & N values on G.INP Bearer 0 and Bearer 1 which one should I use to get the FEC overheads ?


Code: [Select]
adsl info --stats

                Down            Up


                        VDSL2 framing
                        Bearer 0
MSGc:           -6              26
B:              227             191
M:              1               1
T:              0               41
R:              10              12
S:              0.1815          0.9566
L:              10492           1706
D:              4               1
I:              238             102
N:              238             204
Q:              4               0
V:              0               0

                        Bearer 1
MSGc:           90              -6
B:              0               0
M:              2               0
T:              2               0
R:              16              0
S:              10.6667         0.0000
L:              24              0
D:              1               0
I:              32              0
N:              32              0
Q:              0               0
V:              0               0

 >

« Last Edit: August 05, 2016, 06:38:32 PM by NewtronStar »
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Interceptor121

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Re: DLM put me back on fast path after 4 months
« Reply #17 on: August 05, 2016, 06:39:16 PM »

Bearer 0=data bearer 1=GINP
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ejs

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Re: DLM put me back on fast path after 4 months
« Reply #18 on: August 05, 2016, 06:45:25 PM »

Not necessarily what exactly?

You would not necessarily sync at 42300 if FEC were off, since you would also have removed any coding gain.
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Interceptor121

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Re: DLM put me back on fast path after 4 months
« Reply #19 on: August 05, 2016, 06:47:27 PM »

You would not necessarily sync at 42300 if FEC were off, since you would also have removed any coding gain.
I doesn't really matter. I am capped at 40000 and get FEC as by product. The max rate is 43400 but this is also a calculation
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ejs

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Re: DLM put me back on fast path after 4 months
« Reply #20 on: August 05, 2016, 06:53:09 PM »

Bearer 0=data bearer 1=GINP

With G.INP, bearer 0 carries the data, and bearer 1 carries the overhead data (messages for things like organising bitswaps or exchanging stats and error counters). Without G.INP, those overhead messages are mixed into bearer 0. The line labelled "OR:" further down the stats gives that overhead rate in kbit/s.
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Interceptor121

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Re: DLM put me back on fast path after 4 months
« Reply #21 on: August 05, 2016, 07:09:22 PM »

FEC is only active on the bearer 0 the bearer 1 is fastpath and has no RS error correction. I understand this is because retransmission needs to be fast.
So the G.INP overhead is all goes on bearer 1 and the FEC overhead is only on what is on bearer 0.
As FEC is taken off the sync rate and G.INP is not according to wwwombat than the FEC overhead is calculated as he said it is on bearer 0?
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NewtronStar

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Re: DLM put me back on fast path after 4 months
« Reply #22 on: August 05, 2016, 07:42:41 PM »

Still don't really understanding G.INP now from what I know it's like two channels working independently the uncorrected errors that need to be re-transmitted go into bearer 0 and then overheads FECs will be added to those packets the normal data that has no errors is sent to bearer 1 with no overheads.

Again I am not 100% sure and maybe completely wrong here.
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burakkucat

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Re: DLM put me back on fast path after 4 months
« Reply #23 on: August 05, 2016, 08:35:21 PM »

Again I am not 100% sure and maybe completely wrong here.

I wonder if this guide will help your understanding?  :-\  :)
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Interceptor121

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Re: DLM put me back on fast path after 4 months
« Reply #24 on: August 05, 2016, 08:35:38 PM »

https://www.broadcom.com/collateral/wp/XDSL-WP101-R.pdf

I think the idea is that the bearer1 is idle until such time a retransmission is requested

When a data unit is received, its Frame Check Sequence (FCS) is checked, and a first
retransmission request is immediately launched if it is found to be corrupted. Even if corrupted, the data
units are pushed into the receive buffer (R). If the retransmitted data unit arrives while the corrupted
one is still present in the receive buffer, the corrupted data is replaced. If the retransmitted data unit
does not arrive on time, the corrupted data will be further processed by the receiver data path


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ejs

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Re: DLM put me back on fast path after 4 months
« Reply #25 on: August 05, 2016, 08:43:11 PM »

If you look the stats from a connection with G.INP, they show that there is FEC on both bearer 0 and bearer 1.

The overhead that goes into the separate (much smaller) bearer 1 is not G.INP specific. It's the general management messages that a present with all VDSL2 connections. Perhaps it gets put into a separate bearer channel because those messages do not need to be protected by retransmission, and it'll be simpler for the other end to just re-send the message if it doesn't receive the expected reply.

Bearer 1 is not a separate channel only for retransmitted data.

Without G.INP, the management overheads are mixed in with bearer 0 (look at where the OR values are in the stats).

The net data rate is still the net data rate, you don't need to subtract any G.INP overhead from it. The net data rate for bearer 1 is zero, there's no user data, it's all management overheads. If G.INP is working hard and doing lots of retransmission, it will affect the throughput, but only while the retransmission is happening. G.INP uses its own performance monitoring values, such as leftrs (low error-free throughput seconds, recording the amount of time the throughput was below a threshold) and mineftr (recording the minimum error-free throughput).
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NewtronStar

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Re: DLM put me back on fast path after 4 months
« Reply #26 on: August 05, 2016, 08:58:45 PM »

Thankyou ejs that is a post I can understand on how G.INP works   :)
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Interceptor121

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Re: DLM put me back on fast path after 4 months
« Reply #27 on: August 05, 2016, 09:07:29 PM »



Bearer 1 is not a separate channel only for retransmitted data.



I understand bearer 1 is exactly only for retransmitted data. That is why there is no upload on this bearer
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NewtronStar

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Re: DLM put me back on fast path after 4 months
« Reply #28 on: August 05, 2016, 09:23:18 PM »

(look at where the OR values are in the stats).

Maybe you could make a judgment on my line with the OR values below

Code: [Select]
                        Bearer 0
INP:            51.00           0.00
INPRein:        1.00            0.00
delay:          0               0
PER:            0.00            9.84
OR:             0.01            26.00
AgR:            40048.20        6397.59

                        Bearer 1
INP:            2.50            0.00
INPRein:        2.50            0.00
delay:          0               0
PER:            16.06           0.01
OR:             47.81           0.01
AgR:            47.81           0.01

[Moderator edited to fix the broken [code][/code] tags.]
« Last Edit: August 05, 2016, 09:43:20 PM by burakkucat »
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ejs

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Re: DLM put me back on fast path after 4 months
« Reply #29 on: August 05, 2016, 09:42:38 PM »

People with G.INP active on both the upstream and the downstream would have bearer 1 upstream and downstream. But bearer 1 is not for retransmitted packets.

Let's look at digitalnemesis's stats from earlier in this thread. They have no G.INP.

Code: [Select]
                        Bearer 0
INP:            0.00            0.00
INPRein:        0.00            0.00
delay:          0               0
PER:            2.53            14.23
OR:             75.71           20.23
AgR:            50479.97        8596.66

Bearer 0 carries 75.71 kbit/s of general management overhead downstream and 20.23 kbit/s upstream.

Here are some old stats from a random connection with G.INP down and up.

Code: [Select]
                        Bearer 0
INP:            52.00           46.00
INPRein:        1.00            0.00
delay:          0               0
PER:            0.00            0.00
OR:             0.01            0.01
AgR:            40368.53        15052.70

                        Bearer 1
INP:            2.50            4.00
INPRein:        2.50            4.00
delay:          0               0
PER:            16.06           16.06
OR:             47.81           31.87
AgR:            47.81           31.87

There's 47.81 kbit/s general management overhead downstream, and 31.87 kbit/s upstream, and they have both been moved from bearer 0 to bearer 1.

There's a small amount of these management overheads on all DSL connections, used for things like when your modem wants to know the upstream CRC count, it has to ask the DSLAM for that number, or if the DSLAM wants to know the current downstream SNRM, it has to ask your modem for that value.

@NewtronStar

Because you have G.INP on the downstream but not the upstream, you have bearer 1 for the downstream but not the upstream. 26 kbit/s management overheads get mixed into upstream bearer 0. For the downstream, with G.INP, the 47.81 kbit/s of overheads have been moved into the separate bearer 1.
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