ARP, BGP, ICMP

It’s easy as 123

How to find your MAC address(es)• Why plural?– Each adapter has its own MAC address

ifconfig -a

XX:XX:XX:YY:YY:YYInterface IDVendor ID

Intel owns

00:90:2700:A0:8300:A0:C9 00:AA:00

…

Cisco owns

00:90:B100:90:2B00:90:8600:90:92

…

Routing on MAC Addresses

H2

H1H3

S1 S2

AA:AA:AA:AA:AA:AA CC:CC:CC:CC:CC:CC

BB:BB:BB:BB:BB:BB

Dest Port

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

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-EFPanda Express

192.168.0.1Panda

192.168.0.5Kay

192.168.0.100Router (Port 1)

65.91.53.96Router (Port 2)

65.91.7.210

Q1: Panda Express

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…

Ping

ping www.google.com

Traceroute

TTL Expired

traceroute www.google.com

Tracepath

Need Fragmentation (PMTU Discovery)

tracepath www.google.com

…