1 7 Ping Program

2 7 Introduction - Problem How do I know if a host is reachable?

3 7 ICMP echo request / reply Type ( 0 or 8 )code ( 0 )checksum Optional data identifierSequence number Ping program uses : ICMP echo request (type 8) ICMP echo reply (type 0)

4 7 Ping IP Address = IP Address = ICMP Reply ping ICMP Request

5 7 Ping output D:\>ping Pinging cio-sys.cisco.com [ ] with 32 bytes of data: Reply from : bytes=32 time=190ms TTL=239 Reply from : bytes=32 time=180ms TTL=239 ( Success rate is 100 percent (5/5), round-trip min/avg/max = 192/192/192ms ) (0% packet loss)

6 7 Ping options Usage: ping [-t] [-a] [-n count] [-l size] [-f] [-i TTL] [-v TOS] [-r count] [-s count] [[-j host-list] | [-k host-list]] [-w timeout] destination-list Options: -t Ping the specifed host until interrupted. -a Resolve addresses to hostnames. -n count Number of echo requests to send. -l size Send buffer size. -f Set Don't Fragment flag in packet. -i TTL Time To Live. -v TOS Type Of Service. -r count Record route for count hops. -s count Timestamp for count hops. -j host-list Loose source route along host-list. -k host-list Strict source route along host-list. -w timeoutTimeout in milliseconds to wait for each reply.

7 7 Exercise: Find out about the PING options