[c-nsp] DOCSIS 3.0 & PPPoE/L2TP compatibility

Scott Helms khelms at ispalliance.net
Wed Aug 1 15:23:29 UTC 2012

I did PPPoE for open access on cable networks starting back in DOCSIS 
1.0 and that (and PPTP for that matter) is a dead end IMO.  Get to 
BSoD/TLS which is a CableLabs (the guys who write and test the DOCSIS 
spec) standard and will be supported on all of the D3 chassis no matter 
if its Arris, Cisco, Motorola, or Casa.

The guys at the cable company could have gone with a Cisco 10k or a 
7225(smaller systems only) and I believe both of those still support 
being a LNS for PPPoE, but again Cisco is really the only one and good 
luck getting any help from their TAC on setting it up.

On 8/1/2012 10:57 AM, iptech wrote:
> Ray,
> Yes PITA indeed.
> Our 7200 are G2, but we were still planning on moving away from them.
> I presume you guys are staying on the 7200s meantime, to accomodate 
> the PPTP requirement?
> Thanks,
> On 7/31/2012 10:35 PM, Ray Burkholder wrote:
>> As far as I can tell, and from my conversations with the guys at 
>> Cablevision, there isn't anything underhanded.  The ARRIS gear simply 
>> doesn't do PPPOE stuff. They've looked at various scenarios, and PPTP 
>> seems to be the winner.
>> Their Cisco CMTS gear was EOL'd a long time ago, and I don't think 
>> there is/was a migration path  for handling recent DOCSIS and 
>> speeds.  So they side stepped it.  Their ARRIS box is a single 
>> chassis with a redundant cards in it.  With DOCSIS 3, they get better 
>> speeds and stuff out of it.
>> I havn't seen the numbers, but I gather it will handily handle all 
>> the traffic for all the ISP's.
>> It does become a PITA for us as ISP's,  as we have  to convert all 
>> our subscribers over to PPTP.
>> What are you doing with your old 7200's?  Are they G2's?
>> Ray.
>>> -----Original Message-----
>>> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
>>> bounces at puck.nether.net] On Behalf Of iptech
>>> Sent: Tuesday, July 31, 2012 12:28
>>> To: Brian Mengel
>>> Cc: cisco-nsp at puck.nether.net
>>> Subject: Re: [c-nsp] DOCSIS 3.0 & PPPoE/L2TP compatibility
>>> Thanks Brian,
>>> I am struggling with this one, as I suspect the cableco are skipping
>>> round a problem with their in house setup, and trying to make me 
>>> bend to
>>> get it working, which I am reluctant to do, as its a big step backwards
>>> for us.
>>> They are moving from a Cisco CMTS to a Arris, therefore it is highly
>>> possible this will be a new box. What they have told me is that their
>>> CMTS setup will now be L3 as opposed to L2. The reasons behind this are
>>> not clear.
>>> Appreciate any pointers on this one.
>>> Thanks v much.
>>> On 7/31/2012 11:54 AM, Brian Mengel wrote:
>>>> We run a mix of Cisco and Arris CMTS in our network and have found
>>>> both to share the same feature set (at least for the features we
>>>> need).  If there is a problem with L2TP its not going to be the result
>>>> of the DOCSIS 3.0 upgrade but rather an issue with the Arris CMTS.  I
>>>> would recommend getting a technical contact at Arris from your partner
>>>> MSO and explaining your situation to them and seeing what they can
>>>> provide as a resolution.  Its possible that the Arris outright doesn't
>>>> support L2TP, but I suspect there may be other things going on.
>>>> On Sat, Jul 28, 2012 at 6:48 PM, iptech <iptech at northrock.bm> wrote:
>>>>> Hi,
>>>>> No takers?
>>>>> Would really appreciate some feedback/pointers.
>>>>> Thank you.
>>>>> On 7/27/2012 2:57 PM, iptech wrote:
>>>>>> Hi,
>>>>>> We are a small ISP and have a setup in place with the local cable
>>> company
>>>>>> for terminating their users via L2TP for Internet access. However 
>>>>>> they
>>> have
>>>>>> just announced to us that they are moving to a DOCSIS 3.0 compliant
>>> setup,
>>>>>> and this standard no longer supports PPPoE via L2TP, and can now 
>>>>>> only
>>> offer
>>>>>> PPTP for terminating with us.
>>>>>> We have already begun replacing our Cisco 7206VXR LNS devices with
>>> Cisco
>>>>>> ASR 1Ks and as you will be aware the older 7206 can do both L2TP and
>>> PPTP,
>>>>>> whereas the ASR1k can do only L2TP.
>>>>>> I do not have any experience in the cable arena, but from what I 
>>>>>> have
>>> read
>>>>>> in the DOCSIS standards, each version has maintained backwards
>>>>>> compatibility, therefore I am very surprised our CableCo has claimed
>>> they
>>>>>> cannot do PPPoE/L2TP anymore.
>>>>>> The CMTS they are currently using is a Cisco, and now they are 
>>>>>> moving to
>>> a
>>>>>> new ARRIS CMTS. I have not been able to find any information on this
>>> device
>>>>>> and what it can do or not.
>>>>>> With the ASR1K marked as the natural upgrade path for LNS functions,
>>>>>> therefore I cannot believe that it is not fully compatible with 
>>>>>> DOCSIS 3.0.
>>>>>>   From what I can tell the only way to accommodate the new CMTS PPTP
>>>>>> connections will be to terminate them on the legacy 7206VXR, 
>>>>>> which at
>>> the
>>>>>> end of the day is a backwards step.
>>>>>> I would greatly appreciate if anyone can give me any pointers and/or
>>>>>> suggestions on this matter, so I can understand it and move it 
>>>>>> forward.
>>>>>> FYI: The driver for the CMTS upgrades is to offer higher bandwidth
>>> access
>>>>>> speeds 15mb-20mb.
>>>>>> Thank you.
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Scott Helms
Vice President of Technology
(678) 507-5000

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