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[111888]

Does Openreach support BitSwap, or SRA?

[burakkucat]

All Openreach VDSL2 products will use bit swapping.

[j0hn]

Does Openreach support BitSwap, or SRA?

Yes.

OpenReach VDSL2 uses bitswap.
OpenReach G.Fast uses bitswap and SRA.

OpenReach were trialling SRA on VDSL2 but nothing appears to have come from the trials.

[Alex Atkin UK]

SRA seems less useful than I originally thought it was, if it can only reduce the speed not increase it.

[Chrysalis]

SRA seems less useful than I originally thought it was, if it can only reduce the speed not increase it.

Its primary purpose isnt to increase speed, for me the benefit was to deal with significant amounts of variable noise on a line without interruption to service.  Now you get an effective speed increase as SRA will auto recover speed if snrm goes back up after a reduction, whilst if you sync at a lower speed without SRA, if SNR increases you wont recover speed without another resync.

[Alex Atkin UK]

Its primary purpose isnt to increase speed, for me the benefit was to deal with significant amounts of variable noise on a line without interruption to service.  Now you get an effective speed increase as SRA will auto recover speed if snrm goes back up after a reduction, whilst if you sync at a lower speed without SRA, if SNR increases you wont recover speed without another resync.

I suppose, but the fact increasing the speed back up needs a re-sync is not "seamless".  Or is this something specific to how DLM interacts with g.FAST?

[111888]

All Openreach VDSL2 products will use bit swapping.

should i enable bit swap on my router? im worried DLM already uses something similar and it will conflict.

[burakkucat]

should i enable bit swap on my router?

Yes, it should be enabled by default. Without bit-swapping, the device will slowly map all bits as "out of use" and then the only recovery from that situation would be a device re-start.

im worried DLM already uses something similar and it will conflict.

No, there is nothing for you to be concerned about. The DLM expects all CPEs to have bit-swapping enabled.

[Alex Atkin UK]

Also of note is after a re-sync you will often see bitswapping off in the stats.  This is normal and it will say its enabled after a while, possibly after it first needs to actually do bitswapping.

[Weaver]

I complained to Andrews and Arnold about the (manufacturer’s stupid default) config that was shipping in one of their routers, either DLink or ZyXEL, I’ve forgotten now. These devices were shipping with bitswap off, but I was amazed about how not really really bad their performance was. They seemed to manage to cope better than I expected without bitswap and I don’t understand how.

[burakkucat]

I complained to Andrews and Arnold about the (manufacturer’s stupid default) config that was shipping in one of their routers, either DLink . . .

It was the D-Link device that A&A were then providing for use in bridging modem-only mode.

[Weaver]

Thanks for reminding me. My own DLINK DSL-320B-Z1 units were reconfigured to have bitswap turned on, and I was trying to get AA to change their standard configuration to be likewise. I don’t understand why bitswap on/off should even be an option, unless it’s something to do with a rubbish device not having monitored tones?