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Unformatted text preview: nsists of two LANs connected by a router. A client running on host A, which is attached to LAN1, sends a sequence of data bytes to a server running on host B, which is attached to LAN2. There are eight basic steps: 1. The client on host A invokes a system call that copies the data from the client’s virtual address space into a kernel buffer. 610 Host A client (1) data CHAPTER 12. NETWORK PROGRAMMING Host B server (8) data internet packet (2) data PH FH1 protocol software protocol software (7) data PH FH2 LAN1 frame LAN1 adapter Router LAN1 adapter LAN2 adapter LAN2 adapter (6) data PH FH2 (3) data PH FH1 LAN1 (4) data LAN2 frame PH FH1 data PH FH2 (5) LAN2 protocol software Figure 12.7: How data travels from one host to another on an internet. Key: PH: internet packet header, FH1: frame header for LAN1, FH2: frame header for LAN2. 2. The protocol software on host A creates a LAN1 frame by appending an internet header and a LAN1 frame header to the data. The internet header is addressed to internet host B. The LAN1 frame header is addressed to the router. It then passes the frame to the adapter. Notice that the payload of the LAN1 frame is an internet packet, whose payload is the actual user data. This kind of encapsulation is one of the fundamental insights of internetworking. 3. The LAN1 adapter copies the fr...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.

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