Why just not use l2tp tunnel-switching that's very old and proven technology? Transport interface for switched tunnels can be put into routing instance if needed.
Regarding PS interfaces, they can terminate ipoe and ppp (potentially, didn't try it, but should just work), but if your PPP session is already encapsulated in L2TP, I doubt that PS interface can process it. L2TP is already L3 and requires it's own service interface, then PS interface is for subscribers coming from L2 domain, imho.
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Kind regards,
Andrey
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Original Message:
Sent: 09-15-2022 04:15
From: TRISTAN BENDALL
Subject: Layer 2 PPP sessions for LNS
Hi all
I'm trying to see if an architecture is possible, I think it is based on some Juniper articles, see below.
Current scenario:
- We are a wholesale ISP, aggregating access networks and reselling them (call us ISP C)
- We have L2TP relationships with various Access ISPs, call them ISP A & ISP B
- We have CPEs establishing PPP sessions across these tunnels into our LNS, either into MPLS or Internet VRF
Proposed design:
- Using the same L2TP tunnels, terminate/stitch the PPP sessions straight into some kind of L2VPN (VPLS, PW) and handoff to customer (Wholesale Customer)
- Do not assign IP addresses to subscriber (in order for Customer to use own L3 scheme)
- Ability to use dynamic-profiles, dynamic interfaces, RADIUS attributes, RADIUS auth (of some kind)

MPLS Pseudowire Subscriber Logical Interfaces | Junos OS | Juniper Networks
Prior to Junos OS Release 19.1R1, the only supported encapsulation type on the pseudowire subscriber interfaces included:
Starting in Junos OS Release 19.1R1, additional encapsulations are added to the pseudowire subscriber transport and service logical interfaces. The transport logical interface supports Ethernet VPLS encapsulation, and provisions for terminating the interface on the l2backhaul-vpn
routing-instance. The service logical interface supports circuit cross-connect (CCC) encapsulation, and provisions for terminating the interface on locally switched Layer 2 circuits.
Understand that I want to use "service logical interfaces" for whatever pops out of the PPP tunnel, rather than "transport logical interfaces", which is the mechanism for getting the encapsulated traffic towards the LNS.
Is this possible?
Tristan
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TRISTAN BENDALL
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