1. CSCE 515: Computer Network Programming Chin-Tser Huang huangct@cse.sc.edu University of South Carolina

2. 2/10/20042 Internet Control Message Protocol (ICMP) Utilized by either IP or higher layer (TCP or UDP) to communicate conditions that require attention Two main categories Query message Error message Usage of an ICMP message is determined by type and code fields

3. 2/10/20043 ICMP Message Format typecodechecksum payload 078151631

4. 2/10/20044 ICMP Address Mask Request and Reply type(17 or 18)code(0) checksum 078151631 subnet mask sequence numberidentifier

5. 2/10/20045 ICMP Timestamp Request and Reply type(13 or 14)code(0) checksum 078151631 originate timestamp sequence numberidentifier receive timestamp transmit timestamp

6. 2/10/20046 ICMP Unreachable Error type(3)code(0-15) checksum IP header + first 8 bytes of original datagram data 078151631 unused (must be 0)

7. 2/10/20047 ICMP Time Exceeded type(11)code(0 or 1) checksum IP header + first 8 bytes of original datagram data 078151631 unused (must be 0)

8. 2/10/20048 ping Program Test whether another host is reachable -n option to set number of echo request to send -i option to set TTL -r option to record route -s option to set timestamp -w option to set timeout to wait for each reply

9. 2/10/20049 ICMP Echo Request and Reply type(0 or 8)code(0) checksum optional data 078151631 sequence numberidentifier

10. 2/10/200410 IP Record Route Option code 1 lenptrIP addr #1IP addr #2…IP addr #9 11444 39 bytes

11. 2/10/200411 traceroute Program Display the route that IP datagrams follow from one host to another Can use IP source route option -g option to specify intermediate routers to be used with loose source routing (up to 8 times) -G option to specify intermediate routers to be used with strict source routing (up to 8 times)

12. 2/10/200412 IP Source Routing S dest = D {#R1,R2,R3} R1 dest = R1 {#R2,R3,D} R2 dest = R2 {R1,#R3,D} R3 dest = R3 {R1,R2,#D} D dest = D {R1,R2,R3#}

13. 2/10/200413 IP Source Route Option code 1 lenptrIP addr #1IP addr #2…IP addr #9 11444 39 bytes

14. 2/10/200414 IP Processing IP output: calculate next hop router (if necessary) our packet (one of our IP address or broadcast addresses)? process IP options IP input queue ICMP UDPTCP routing daemon route command netstat command routing table network interfaces IP layer source routing forward datagram (if forwarding enabled) ICMP redirects routing table updates from adjacent routers

15. 2/10/200415 Next Class Routing principles Routing protocols Read TI Ch. 9, 10 Project 2 will be passed out