# Bitswapping issue



## txgt (Aug 20, 2012)

Hi! My DSL modem is D-link 2520U/D4 FW 1.0.4
I'm curious about my bitswap counters in status menu. When Bitswap is disabled I get upstream bitswap count rising every second and zero on downstream. When Bitswap is enabled I can have zero counts on both upstream and downstream in first few days after establishing dsl connection. After about a week I can have about 5 bitswaps on downstream and zero on upstream.
Can you explain me this behaviour?
And what can you say about my parameters given below?

_ Main stats_

Downstream rate:
18431 Kbps
Upstream rate:
1023 Kbps
Link Power State:
L0
Mode:
ADSL2+
Trellis:
U:ON /D:ON
Line status:
No Defect

_ Counters tab after 30 min uptime (bitswap disabled)_

Parameter Up Down
Super Frames 134463 128476
Super Frames Errors 102 5
RS Words 0 0
RS Correctable Errors 0 0
RS Uncorrectable Errors 0 0
HEC Errors 84 1
OCD Errors 26 0
LCD Errors 0 0
Total Cells 94253625 5230612
Data Cells 6580423 408779
Drop Cells 11106565 11106565
Bit Errors 0 382
Total ES 24832 660
Total SES 79 2
Total UAS 103 103
AS 2168 2168
INP 0.00 0.00
PER 16.12 16.86
Delay 0.11 msec 0.49 msec
OR 36.21 8.06
Bitswap 449 0

_ Line status tab_

Parameter Up Down
Rate 1023 Kbps 18431 Kbps
Attainable rate 1275 Kbps 21728 Kbps
SNR Margin 13.9 dB 7.1 dB
Attenuation 11.1 dB 23.5 dB
Output Power 18.5 dBm 12.4 dBm


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## Wand3r3r (Sep 17, 2010)

With bit swapping the router can swap the bits around and redistribute the bits to other channels by using any spare SNR at other frequencies or increasing the gain. 

Without bit-swapping, your connection would lose sync every time there was a noise burst that meant any sub-channel wasn't able to transmit its allocated number of bits

Read more: ::. Kitz - ADSL Technology & DMT - Bit Allocation + Bit Swapping.::


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