ICMP Message Transport - Computer Network - Lecture Slides, Slides of Computer Networks

Download ICMP Message Transport - Computer Network - Lecture Slides and more Slides Computer Networks in PDF only on Docsity!

COMPUTER

NETWORKS

Lecture-

Review Lecture 32

Fragmentation in IPV

Use of Multiple Headers

IPV6 Addressing

ICMP

Best Effort Semantics and Error

Detection

Types of ICMP Messages

ICMP Message Transport

How it Works?

ICMP messages sent in response to

incoming datagrams with problems

ICMP message not sent for ICMP

message

Using ICMP to Test Reachability

An internet host, A, is reachable from

another host, B, if datagrams can be delivered from A to B

Ping program tests reachability - sends

datagram from B to A that A echoes back to B

Uses ICMP echo request and echo reply

messages

Internet layer includes code to reply to

incoming ICMP echo request messages

Using ICMP to Trace a Route

tracert (Windows version) Sends ICMP echo messages with increasing TTL

Router that decrements TTL to 0 sends ICMP time exceeded message, with router's address as source address First, with TTL 1, gets to first router, which discards and sends time exceeded message Next, with TTL 2, gets through first router to second router Continue until an ICMP echo reply message from destination received

The Last Address printed by Traceroute

There are two possibilities used to detect the destination:

Send an ICMP echo request, destination host will generate an ICMP echo reply

Send a datagram to a non-existent application, destination host will generate an ICMP destination unreachable message

Summary

ICMP Message Transport

Using ICMP to Test Reachability

Using ICMP to Trace a Route

The Address Printed by Trace-route

Using ICMP for Path MTU Discovery