Networking Concepts Review - CCIE Routing and Switching Exam Certification Guide - page 22

Telnet Example Figure 2-3

TCP Data TCP Data Segment

Segment

Host 1 Packet IP TCP Data Packet

IP TCP Data

Host 2

802.3 IP TCP Data

802.3 IP TCP Data

Ethernet 1 Ethernet 2

Router 2

Router 1 Serial Link

IP TCP Data

IP TCP Data HDLC IP TCP Data

Destination IP? Destination IP?

When the frame arrives to Router 1, it converts the bits into a frame, removes the frame headers
(data link), checks the destination IP address (network), places a serial link header to the packet,
which makes it a serial frame, and forwards the frame to the serial link (data link), which sends
it as bits.

Router 2 receives the bits, converts to a frame, removes the serial encapsulation headers, checks
the destination IP address (network), adds an Ethernet header to the packet, which makes it a
frame, and places a frame on Ethernet 2 (data link). Host 2 receives bits (physical) from the
Ethernet cable and converts the bits into a frame (data link). Then, the IP protocol is examined
and the packet data is forwarded to TCP, which checks the segment number for errors and
forwards the segment to TCP port 23 (Telnet), which is the application.

Numeric Conversion
This section focuses on the techniques used to convert between decimal, binary, and hexadecimal
numbers. Although there might not be a specific question on the exam that asks you to convert
a binary number to decimal, you need to know how to convert these numbers to complete
problems on the test. A diagram might show a Token Ring with a decimal number but the RIF
might be shown as hexadecimal. An IP address might be shown as binary or in dotted decimal
format. Some show commands have output information in hexadecimal or binary formats. As
a CCIE candidate, you must be prepared.