This article is pretty good:
https://supportforums.cisco.com/document/94171/asr9000xr-bng-deployment-guide
Hardware requirements
The hardware you require for BNG on the ASR9000 is:
- Any typhoon linecard such as the A9K-MOD80-SE, A9K-24x10, 36x10 and MOD160.
- A9K-RSP440-SE
Note that for both the RSP and the linecard we need to have the "SE" or Service Edge variant.
Also the ASR9001 will support BNG.
Trident linecards are not supported for subscriber termination, but they can be used as core facing linecard for transport
The MOD80 is a 2NP based linecard. Per NP we support 32k sessions with 64k per linecard.
Per Port we support up to 8K sessions when they are running QOS. This because of the QOS architecture within the NP that won't allow more then 8k parent shapers per phyiscal port. (that restriction is partially lifted in XR4.3.1 which allows for QOS chunk allocation more dynamically. You still have 32k parent shapers, but you can instruct a subinterface to use a chunk. This means a limitation of 8k per vlan, 32k per NPU)
These retrictions apply regardless of whether you are using LC or RSP based subscribers.
All linecards that run BNG need to be of the Typhoon kind (NP4). Your core facing interfaces if not running BNG can be Trident based or SIP700 based. However if you are using L2TP, then your core facing LC's need to be NP4 also. This is because the L2TP decap is not implemented in SIP or Trident which is handled by the core facing LC in the downstream direction.
