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Unformatted text preview: am becomes 17 frames across the SLIP link.
11.5 No. The problem is that when the application times out and retransmits, the IP
datagram generated by the retransmission has a new identification field. Reassembly is
done only for fragments with the same identification field.
11.6 The identification field in the IP header (47942) is the same.
11.7 First, from Figure 11.4 we see that gemini does not have outgoing UDP
checksums enabled. It's highly probable that the operating system on this host (SunOS
4.1.1) is one that never verifies an incoming UDP checksum unless outgoing UDP
checksums are enabled. Second, it could be that most of the UDP traffic is local traffic,
instead of WAN traffic, and therefore not subject to all the vagaries of WANs.
11.8 The loose and strict source routing options are copied into each fragment. The
timestamp option and the record route option are not copied into each fragment-they
appear only in the first fragment.
11.9 No. We saw in Section 11.12 that many implementations can filter incoming
datagrams destined for a given UDP port number based on the destination IP address,
source IP address, and source port number. Chapter 12
12.1 Broadcasting by itself does not add to network traffic, but it adds extra host
processing. Broadcasting can lead to additional network traffic if the receiving hosts
incorrectly respond with errors such as ICMP port unreachables. Also, routers normally
don't forward broadcast packets, whereas bridges normally do, so broadcasts on a bridged
network can travel much farther than they would on a routed network.
12.2 Every host receives a copy of every broadcast. The interface layer receives the
frame, and passes it to the device driver. If the type field is for some other protocol, it is
the device driver that discards the frame.
12.3 First execute netstat -r to see the routing table. This shows the names of all the
interfaces. Then execute ifconfig (Section 3.8) for each interface: the flags tell if the
interface supports broadcasting, and if so t...
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.
- Spring '12