TCP IP Illustrated

Some books state the minimum as 64 bytes which

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Unformatted text preview: f 46 bytes shown in Figure 1.7, since the corresponding maximum (1500 bytes) is what's referred to as the MTU-maximum transmission unit (Figure 2.5). We use the MTU often, because it limits the size of an IP datagram, but are normally not concerned with the minimum. Most device drivers or interface cards automatically pad an Ethernet frame to the minimum size. The IP datagrams on lines 3,4, and 5 (containing the TCP segments) are all smaller than the minimum, and have also been padded to 60 bytes. file:///D|/Documents%20and%20Settings/bigini/Docu...homenet2run/tcpip/tcp-ip-illustrated/arp_addr.htm (6 of 12) [12/09/2001 14.46.39] Chapter 4. ARP: Address Resolution Protocol The next field on line 1, arp who-has, identifies the frame as an ARP request with the IP address of svr4 as the target IP address and the IP address of bsdi as the sender IP address, tcpdump prints the hostnames corresponding to the IP address by default. (We'll use the -n option in Section 4.7 to see the actual IP addresses in an ARP request.) From line 2 we see that while the ARP request is broadcast, the destination address of the ARP reply is bsdi (0:0:c0:6f:2d:40). The ARP reply is sent directly to the requesting host; it is not broadcast. tcpdump prints arp reply for this frame, along with the hostname and hardware address of the responder. Line 3 is the first TCP segment requesting that a connection be established. Its destination hardware address is the destination host (svr4). We'll cover the details of this segment in Chapter 18. The number printed after the line number on each line is the time (in seconds) when the packet was received by tcpdump. Each line other than the first also contains the time difference (in seconds) from the previous line, in parentheses. We can see in this figure that the time between sending the ARP request and receiving the ARP reply is 2.2 ms. The first TCP segment is sent 0.7 ms after this. The overhead involved in using ARP for dynamic address resolution in this example is less than 3 ms....
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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.

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