Layer 2 forwarding

from Wikipedia, the free encyclopedia
L2F in the TCP / IP protocol stack :
application L2F
transport UDP
Internet IP ( IPv4 , IPv6 )
Network access Ethernet Token
bus 		Token
ring 		FDDI ...

Layer 2 Forwarding ( L2F ) is a network protocol that was developed to tunnel multiple connections; it is characterized by high performance , as the packet uses little overhead .

Layer-2 forwarding was developed roughly at the same time as PPTP by the companies Cisco Systems , Northern Telecom and Shiva and defined in RFC2341. In 1999, both protocols from Cisco Systems and Microsoft were merged in L2TP .

Package details

The packet consists of the L2F header, the payload and the checksum. It can PPP or SLIP encapsulated be.

Bits 0-12 13-15 16-23 24-31
F. K P S. 0 0 0 0 0 0 0 0 C. Ver Protocol Sequence (opt)
Multiplex ID Client ID
Length Payload offset (opt)
Key (optional)

Payload ( PPP or SLIP )
  L2F checksum (opt)

User identification

The user identification takes place in three steps, whereby the second authentication step is optional. The first authentication takes place at the Internet service provider , the second and third authentication steps take place at the gateway of the router .

Individual evidence

  1. ↑ a b Layer 2 Forwarding Protocol: Details. Retrieved October 11, 2018 .
  2. ↑ Layer 2 Forwarding Protocol: Protocol Definition. Retrieved October 11, 2018 .
  3. ^ Layer Two Forwarding (L2F). Retrieved October 11, 2018 .
  4. ↑ Layer 2 forwarding protocol: packet details. Retrieved October 11, 2018 .
  5. ↑ Layer 2 Forwarding Protocol: Encapsulation. Retrieved October 12, 2018 .
  6. ↑ Layer 2 Forwarding: Authentication. Retrieved October 12, 2018 .