Value,Description,Reference
0,Reserved,[RFC6624]
1,Frame Relay,[RFC4446]
2,ATM AAL5 SDU VCC transport,[RFC4446]
3,ATM transparent cell transport,[RFC4816]
4,Ethernet (VLAN) Tagged Mode,[RFC4448]
5,Ethernet Raw Mode,[RFC4448]
6,Cisco HDLC,[RFC4618]
7,PPP,[RFC4618]
8,SONET/SDH Circuit Emulation Service,[RFC4842]
9,ATM n-to-one VCC cell transport,[RFC4717]
10,ATM n-to-one VPC cell transport,[RFC4717]
11,IP Layer 2 Transport,[RFC3032]
12-14,Unassigned,
15,Frame Relay Port mode,[RFC4619]
16,Unassigned,
17,Structure-agnostic E1 over packet,[RFC4553]
18,Structure-agnostic T1 (DS1) over packet,[RFC4553]
19,VPLS,[RFC4761]
20,Structure-agnostic T3 (DS3) over packet,[RFC4553]
21,Nx64kbit/s Basic Service using Structure-aware,[RFC5086]
22-24,Unassigned,
25,Frame Relay DLCI,[RFC4619]
25-39,Unassigned,
40,Structure-agnostic E3 over packet,[RFC4553]
41,Octet-aligned payload for Structure-agnostic DS1 circuits,[RFC4553]
42,E1 Nx64kbit/s with CAS using Structure-aware,[RFC5086]
43,DS1 (ESF) Nx64kbit/s with CAS using Structure-aware,[RFC5086]
44,DS1 (SF) Nx64kbit/s with CAS using Structure-aware,[RFC5086]
45-127,Unassigned,
128-251,Unassigned,
252-255,Experimental Use,[RFC6624]