CCNA

1. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-1
Ethernet LANs
Exploring the
Packet Delivery
Process

2. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-2
Layer 2 Addressing
 Uses MAC address
 Assigned to end devices

3. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-3
Layer 3 Addressing
 Each NOS has its own Layer 3 address format.
 OSI uses NSAP.
 TCP/IP uses IP.

4. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-4
Host-to-Host Packet Delivery (1 of 10)

5. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-5
Host-to-Host Packet Delivery (2 of 10)

6. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-6
Host-to-Host Packet Delivery (3 of 10)

7. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-7
Host-to-Host Packet Delivery (4 of 10)

8. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-8
Host-to-Host Packet Delivery (5 of 10)

9. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-9
Host-to-Host Packet Delivery (6 of 10)

10. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-10
Host-to-Host Packet Delivery (7 of 10)

11. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-11
Host-to-Host Packet Delivery (8 of 10)

12. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-12
Host-to-Host Packet Delivery (9 of 10)

13. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-13
Host-to-Host Packet Delivery (10 of 10)

14. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-14
Summary
 Layer 2 addresses are MAC addresses.
 Layer 3 addresses are IP addresses.
 If the MAC address is not known, ARP is used to map Layer 2
to Layer 3.
 Switches learn the MAC addressing to port mapping by
monitoring the source addresses of frames.
 When a switch forwards a frame, it does not change the source
or destination Layer 2 address.

15. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-15