DOCSIS 3.0 & PPPoE/L2TP compatibility

iptech iptech at northrock.bm
Wed Aug 1 09:10:31 CDT 2012


Hey Michael,

Thanks for the feedback.

 From the scenarios below, I think that option 3 would be more feasible, 
i.e BSoD L2VPN, via pw. Our max expected number of sessions would not 
exceed 10k, so probably not an hw limiting issue for us.

For option 4, we cannot accommodate this, as we are moving to ASR1K, 
which does not support PPTP, only L2TP.

I am reading through the DOCSIS L2VPN specification to understand the 
model better.

Thanks,

On 7/31/2012 9:03 PM, Michael Bowe wrote:
> Hi iptech
>
> As others have said, early Cisco CMTS could do full bridging and/or PPPoE
> termination, but newer gear is typically L3 style only.
>
> For wholesale, the cableco could do one of these :
>
> * L2 solution : Change your customers to configured as DOCSIS BSoD L2VPN,
> and deliver you one dot1q VLAN per customer. You can continue to use PPPoE
> with this config (sessions landing directly on your LNS). Gotcha: don't know
> about Arris, but Cisco caps you at 4K VLANs per chassis which means this
> solution doesn't scale all that well.
>
> * L2 solution : Change your customers to be setup as DOCSIS BSoD L2VPN, and
> deliver you one MPLS pseudowire per customer. You can continue to use PPPoE
> with this config (sessions landing directly on your LNS). Gotcha: don't know
> about Arris, but Cisco caps you at 16K pw per chassis which means this
> solution only provides moderate scaling. Also you have to somehow terminate
> all these pw (which are "xconnect"s in Cisco-speak).
>
> * L3 soution : change your customers to land on a dedicated bundle and VRF.
> Apply policy based routing to force-forward all the CPE traffic up a VLAN to
> you. If you want to be able to authenticate/count/shape then you probably
> need to terminate this traffic as IPoE (Use a dedicated BNG, or maybe you
> could try Cisco ISG). Cableco would provide the DHCP for the CM, you would
> provide the DHCP for the CPE. CMTS would insert CM MAC as option 82 so you
> know which CPE belongs to which CM/customer.
>
> * L3 solution : last option is to do what they proposed. I would probably
> still implement this with a dedicated bundle and VRF. But rather than having
> to land the sessions as IPoE, you can now have them come in as PPTP. This
> allows you to authenticate/count/shape via your LNS.
>
> Hope that helps,
> Michael.
>
>




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