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

iptech iptech at northrock.bm
Tue Jul 31 11:27:59 EDT 2012


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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