Unformatted text preview: d on many
factors: which type of broadcast address, configuration parameters, and so on.
A class D IP address is called a multicast group address. It is converted to an Ethernet
address by placing its lower 23 bits into a fixed Ethernet address. The mapping is not
unique, requiring additional filtering by one of the protocol modules.
Exercises file:///D|/Documents%20and%20Settings/bigini/Doc...omenet2run/tcpip/tcp-ip-illustrated/broadcas.htm (11 of 12) [12/09/2001 14.47.00] Chapter 12. Broadcasting and Multicasting 12.1 Does broadcasting increase the amount of network traffic?
12.2 Consider 50 hosts on an Ethernet: 20 running TCP/IP and 30 running some other
protocol suite. How are broadcasts from one protocol suite handled by hosts running the
other protocol suite?
12.3 You login to a Unix system that you've never used before and want to find the subnetdirected broadcast address for all attached interfaces that support broadcasting. How can
you do this?
12.4 If we ping the broadcast address with a large packet size, as in
sun % ping 22.214.171.124 1472
PING 126.96.36.199; 1472 data bytes
1480 bytes from sun (188.8.131.52): icmp_seq=0. time=6. ms
1480 bytes from svr4 (184.108.40.206): icmp_seq=0. time=84.
1480 bytes from bsdi (220.127.116.11): icmp_seq=0. time=128.
it works, but increasing the packet size by 1 byte gives us the following error:
sun % ping 18.104.22.168 1473
PING 22.214.171.124: 1473 data bytes
sendto: Message too long
What's going on?
12.5 Redo Exercise 10.6 assuming the eight RIP messages are multicast instead of
broadcast (assume RIP Version 2 is being used). What changes? file:///D|/Documents%20and%20Settings/bigini/Doc...omenet2run/tcpip/tcp-ip-illustrated/broadcas.htm (12 of 12) [12/09/2001 14.47.00] Chapter 13. IGMP: Internet Group Management Protocol IGMP: Internet Group Management
Section 12.4 provided an overview of IP multicasting and described how class D IP addresses are mapped
into Ethernet addresses. We briefly mentioned how multicasting occurs on a single physical network, but said
complications occur when mu...
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