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