| AVP | No. | Usage |
| Acct-Status-Type | 40 | 1 Start |
| User-Name | 1 | Username from authentication (PAP/CHAP) or proxy authentication received on L2TP or received in authentication response |
| Class | 25 | From authentication response if present |
| Chargeable-User-Identity | 89 | Graph name that applies, sanitised to comply with CQM graph name rules.. |
| Called-Station-Id | 30 | Called number as received on L2TP |
| Calling-Station-Id | 31 | Calling number as received on L2TP |
| Service-Type | 6 | Framed |
| Framed-Protocol | 7 | PPP |
| Framed-MTU | 12 | Final MTU being used for session |
| Filter-Id | 11 | Filters in use |
| Session-Timeout | 27 | Absolute limit on session, in seconds, if specified in authentication reply |
| Framed-Interface-ID | 96 | Peer IPv6 Interface ID from PPP IPV6CP |
| Framed-IP-Address | 8 | Peer IPv4 address negotiated in PPP (normally from authentication response) |
| Connect-Info | 77 | Text Tx speed/Rx speed in use |
| Acct-Delay-Time | 41 | Seconds since session started |
| Acct-Event-Timestamp | 55 | Session start time (unix timestamp) |
| Acct-Session-Id | 44 | Unique ID for session |
| NAS-Identifier | 32 | Configured hostname of FireBrick |
| NAS-IP-Address | 4 | NAS IPv4 address if using IPv4 |
| NAS-IPv6-Address | 95 | NAS IPv6 address if using IPv6 |
| NAS-Port | 5 | L2TP session ID |
| Tunnel-Type | 64 | Present for relayed L2TP sessions, L2TP |
| Tunnel-Medium-Type | 65 | Present for relayed L2TP, 1 (IPv4) or 2 (IPv6) |
| Tunnel-Client-Endpoint | 66 | Present for relayed L2TP, text IPv4 or IPv6 address of our address on the outbound tunnel |
| Tunnel-Server-Endpoint | 67 | Present for relayed L2TP, text IPv4 or IPv6 address of the far end address of the outbound tunnel |
| Tunnel-Assignment-ID | 82 | Present for relayed L2TP, text local L2TP tunnel ID |
| Tunnel-Client-Auth-ID | 90 | Present for relayed L2TP, local end hostname quoted by outgoing tunnel |
| Tunnel-Server-Auth-ID | 91 | Present for relayed L2TP, far end hostname quoted by outgoing tunnel |
