1. ARP, BGP, ICMP It’s easy as 123

2. How to find your MAC address(es) Why plural? – Each adapter has its own MAC address ifconfig -a

3. XX:XX:XX:YY:YY:YY Interface IDVendor ID Intel owns 00:90:27 00:A0:83 00:A0:C9 00:AA:00 … Cisco owns 00:90:B1 00:90:2B 00:90:86 00:90:92 …

4. Routing on MAC Addresses H2 H1 H3 S1 S2 AA:AA:AA:AA:AA:AA CC:CC:CC:CC:CC:CC BB:BB:BB:BB:BB:BB DestPort AA:AA:AA: AA:AA:AA 1 BB:BB:BB: BB:BB:BB 2 CC:CC:CC: CC:CC:CC 3 1 2 3 Learning Switch Routing Table for S1

5. P LAN 1 K Router LAN 1 PE F0-0D-F0-0D-F0-0D C0-FF-EE-DE-CA-FF 22-22-22-88-88-88 44-44-44-55-55-55 BE-EF-BE-EF-BE-EF Panda Express 192.168.0.1 Panda 192.168.0.5 Kay 192.168.0.100 Router (Port 1) 65.91.53.96 Router (Port 2) 65.91.7.210 Q1: Panda Express

6. Internet Control Message Protocol (ICMP) Communicate Network Layer information Two uses 1) Diagnosis (Error reporting) 2) Discovery Examples: – Ping/pong – Destination network/host/port unreachable – Source quench – Router advertisement/discovery – TTL expired, Bad IP header, Need fragmentation…

7. Ping ping www.google.com

8. Traceroute TTL Expired traceroute www.google.com

9. Tracepath Need Fragmentation (PMTU Discovery) tracepath www.google.com