Kitz Forum
Broadband Related => Broadband Technology => Topic started by: Weaver on August 13, 2015, 06:16:56 PM
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Try as I might, I simply cannot find any description of how Broadcom’s ATM bytestream compression works.
From the very scant few mentions of its usage, I suspect it's completely throwing out all the ATM cells and just concatenating the payloads which gives it a best-case compression ratio of just below 48/53 (neglecting Broadcom's header and the ATM AAL5 trailer).
This is not to be sneezed at. Chipsets in the DSLAM and modem must both speak Nitro for it to work, whether or not it can auto-detect is unknown. If it could auto-detect, it might be deployable by BT and in that case could have a chance of taking over the world. (But if not, then the sales are 100% or zero.) If your modem can go ~10% faster than someone else’s then you have a killer advantage imo. Speed for free. Yum.
PS: I'm told that Sky use it. Can Sky LLU users use non-Sky CPE? That would answer the question.
(I wonder if there might be any way if adding an autodetect protocol on later? Hmm..)
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Thanks to ejs
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PS: I'm told that Sky use it.
Do they though? Apart from that one article (where its unconfirmed), there's no mention anywhere else and I don't think anyone has ever seen any evidence of it actually in use.
We’re still awaiting confirmation from Sky but we believe this can be employed by ISPs that use Broadcom’s DSLAM network devices inside telephone exchanges.
There seems to be little information about Nitro (https://en.wikipedia.org/wiki/Nitro_%28wireless_networking%29) :(
Nitro is one of several competing incompatible proprietary extension approaches that were developed to increase performance of 802.11g wireless devices, such as 125 High Speed Mode from Broadcom,
There seems to be a French ISP who may have used it - See Freenaute (https://translate.google.co.uk/translate?hl=en&sl=fr&u=http://www.journaldufreenaute.fr/29/08/2006/comment-fait-free-pour-proposer-les-meilleurs-debits-adsl-2-en-france.html&prev=search) to be able to offer upto 28Mbps.
Although they mention the BCM6348 I cant seem to find any mention of it on the Broadcom site nor in the 6348 datasheet. The only English reference I can really find is in relation to Broadcoms NitroQAM for wifi chips.
btw if it is proprietary, then like you say it would mean that both DSLAM and modem would have to be BCM. Sky LLU MSANs are mostly Alcatels which irrc use BCM. Although sky hubs for FTTC have BCM chipsets, I dont think all their adsl2+ routers do/did.
I can't see BTw as eager to use it because they have too many DSLAM/MSANs that arent BCMs.. plus unlike Sky they have absolutely no control at all over the type of modem/routers that are used by the EU.
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And Sky are going to have unhappy LLU customers if their non-Sky CPE, even though illegal, fails to work _at all_, unless there is a protocol auto-detect as mentioned eariler.
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Googling it produces pages of mentions from sites belonging to tester mfrs who say their testers speak Nitro. Cisco makes a box that speaks it. The Broadcom machine has managed to work on all those different mfrs to persuade them to care, unless of course its adoption requires no software in addition in, say, a tester, which I would be slightly surprised about, but it's certainly not impossible, unless I've missed something.