Interleaving - does it increase line speed?

I can't seem to find a definate answer to this question. At the moment
interleaving is set to auto and I can't see from my router if its on or off.
If I were to force it to be on, would that offer any increase in sync speed?

Clearly I could just try it but it takes 48 hours for any change to take
effect so I thought I'd ask here first.

Cheers.

WCZ.

WCZ wrote:
> I can't seem to find a definate answer to this question. At the moment
> interleaving is set to auto and I can't see from my router if its on or off.
> If I were to force it to be on, would that offer any increase in sync speed?
>
> Clearly I could just try it but it takes 48 hours for any change to take
> effect so I thought I'd ask here first.
>
The received wisdom is that it increases latency, but is slightly better
at getting more packets trough a noisy environment.

It won't affect sync SPEED..that is a layer below the interleaving.

It PROBABLY slows down throughput a little, but makes it more reliable.

> Cheers.
>
> WCZ.
>
>

"WCZ" <(E-Mail Removed)> wrote in message
news:fpjn0s$kui$(E-Mail Removed)...
>I can't seem to find a definate answer to this question. At the
>moment interleaving is set to auto and I can't see from my
>router if its on or off. If I were to force it to be on, would
>that offer any increase in sync speed?
>
> Clearly I could just try it but it takes 48 hours for any
> change to take effect so I thought I'd ask here first.

Interleaving allows FEC to work better so a noisy
line will sustain a higher sync speed,

It increases latency somewhat.

On Thu, 21 Feb 2008 11:52:06 +0000, The Natural Philosopher <(E-Mail Removed)>
wrote:

>It won't affect sync SPEED..that is a layer below the interleaving.

BT reckon interleaving reduces the maximum achievable line rate on max
from 8128k to 7616k


Jim.

In message <fpjn0s$kui$(E-Mail Removed)>, WCZ
<(E-Mail Removed)> writes
>I can't seem to find a definate answer to this question. At the moment
>interleaving is set to auto and I can't see from my router if its on or off.
>If I were to force it to be on, would that offer any increase in sync speed?
>
>Clearly I could just try it but it takes 48 hours for any change to take
>effect so I thought I'd ask here first.
>
>Cheers.
>
>WCZ.
>
>
As I understand (and someone who actually knows will be along shortly I
am sure)

Interleaving makes no difference to the sync speed per-se.

It trades off an increase in the overheads in the protocol in order to
reduce packet loss and improve link reliability. However that
improvement can stabilise the link at slightly higher sync speeds, and
stop the exchange from negotiating a lower speed because of dropouts. In
which case it can cause an increase in sync speeds.

Whether it increases or decreases download speeds depends on the level
of packet loss your line experiences without it. If it is significant,
then having interleaving on will (may) reduce the level of
retransmission caused by packet errors and consequently INCREASE
effective download speeds. OTOH if you get no real packet loss with it
off the protocol overheads will be lower, and download speeds may be
higher because a higher proportion of the link traffic is available.

I suspect you will find it hard to tell the difference in terms of
download speed unless your link is particularly good (off is faster), or
particularly bad (on is faster). The variations in speed you get from
the test site is probably going to swamp any difference caused by
interleaving.

I understand however it has a significant impact on round trip "ping"
times, as a consequence I believe gamers tend to turn it off and live
with the increased packet loss and link instability.

Do let us know the results of your experiments.

--
Invalid

On Thu, 21 Feb 2008 14:05:04 +0000, James Egan <(E-Mail Removed)>
wrote:

>
>On Thu, 21 Feb 2008 11:52:06 +0000, The Natural Philosopher <(E-Mail Removed)>
>wrote:
>
>>It won't affect sync SPEED..that is a layer below the interleaving.
>
>BT reckon interleaving reduces the maximum achievable line rate on max
>from 8128k to 7616k

I thought the reduction from the theoretical 8M max was due to the
ATM (etc) overhead.

BICBW

"Invalid" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> In message <fpjn0s$kui$(E-Mail Removed)>, WCZ
> <(E-Mail Removed)> writes
>>I can't seem to find a definate answer to this question. At the moment
>>interleaving is set to auto and I can't see from my router if its on or
>>off.
>>If I were to force it to be on, would that offer any increase in sync
>>speed?
>>
>>Clearly I could just try it but it takes 48 hours for any change to take
>>effect so I thought I'd ask here first.
>>
>>Cheers.
>>
>>WCZ.
>>
>>
> As I understand (and someone who actually knows will be along shortly I am
> sure)
>
> Interleaving makes no difference to the sync speed per-se.
>
> It trades off an increase in the overheads in the protocol in order to
> reduce packet loss and improve link reliability. However that improvement
> can stabilise the link at slightly higher sync speeds, and stop the
> exchange from negotiating a lower speed because of dropouts. In which case
> it can cause an increase in sync speeds.
>
> Whether it increases or decreases download speeds depends on the level of
> packet loss your line experiences without it. If it is significant, then
> having interleaving on will (may) reduce the level of retransmission
> caused by packet errors and consequently INCREASE effective download
> speeds. OTOH if you get no real packet loss with it off the protocol
> overheads will be lower, and download speeds may be higher because a
> higher proportion of the link traffic is available.
>
> I suspect you will find it hard to tell the difference in terms of
> download speed unless your link is particularly good (off is faster), or
> particularly bad (on is faster). The variations in speed you get from the
> test site is probably going to swamp any difference caused by
> interleaving.
>
> I understand however it has a significant impact on round trip "ping"
> times, as a consequence I believe gamers tend to turn it off and live with
> the increased packet loss and link instability.
>
> Do let us know the results of your experiments.
>
> --
> Invalid

I believe that the actual latency with interleaving on depends on the type
of equipment used in the exchange. I get 21ms pinging my ISP with it on so
have never bothered to get it switched off.

On Fri, 22 Feb 2008 06:29:48 +0000, Steve wrote:

> On Thu, 21 Feb 2008 14:05:04 +0000, James Egan <(E-Mail Removed)> wrote:

>>BT reckon interleaving reduces the maximum achievable line rate on max
>>from 8128k to 7616k
>
> I thought the reduction from the theoretical 8M max was due to the ATM
> (etc) overhead.

He's talking about the line rate, not the IP throughput.

--
<http://ale.cx/> (AIM:troffasky) ((E-Mail Removed))
08:38:18 up 13 days, 11:41, 2 users, load average: 1.15, 1.13, 1.05
Convergence, n: The act of using separate DSL circuits for voice and data

"Steve B" <(E-Mail Removed)> wrote in message
news:fpm1n9$jd7$(E-Mail Removed)...
[snip]
> I believe that the actual latency with interleaving on depends on the
> type of equipment used in the exchange. I get 21ms pinging my ISP with
> it on so have never bothered to get it switched off.

The latency introduced fundamentally depends on the interleave depth, which
could be fixed by the exchange equipment or (more likely I think) its
configuration, or chosen based on assessed line conditions.

FWIW, I also got the same RTT using interleave path, which suggests the same
interleave depth was used on this line as yours. As a comparison, on the
same line using fast path, I get 7-8ms.

Alex