CCNA Cisco Certified Network Associate Study Guide - FTP Server

FIGURE 5.2 Frame generated from Host A
>ping 172.16.20.2
Host A
172.16.10.2
ARP request:
What is the hardware
address for 172.16.10.1?
Generate frame and
send packet out in
this frame.
Dest hw
address
Source hw
address
E0: 172.16.10.1 E0: 172.16.20.1
Type Data FCS
ARP reply:
My hardware address
is 00c0.0000.1234.
The IP Routing Process 239
Host A
172.16.20.2
In Figure 5.2, all of the information needed to communicate to the
router is shown: the source and destination hardware addresses, the
source and destination IP addresses, and finally, the data and the
frame’s CRC inside the Frame Check Sequence (FCS) field.
7. The Data Link layer of Host A hands the frame to the Physical layer,
which encodes the 1s and 0s into a digital signal and transmits this out
on the local physical network.
8. The signal is picked up by the router’s Ethernet 0 interface, and the
interface synchronizes on the digital signal preamble and extracts the
frame. The router’s interface, after building the frame, runs a CRC
and, at the end of the frame, checks the FCS field to make sure that the
CRC matches and no fragmentation or collisions occurred.
9. The destination hardware address is checked. Since this will be a
match, the type field in the frame will be checked to see what the
router should do with the data packet. IP is, of course, in the type field,
and the router hands the packet to the IP protocol running on the