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