TCP IP Illustrated

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Unformatted text preview: re 11.13) but here we have set the MTU of the interface on slip to 552, instead of its normal 296. This causes slip to announce an MSS of 512. But leaving the MTU of the SLIP link on bsdi at 296 will cause TCP segments greater than 256 to be fragmented, and we can see how the path MTU discovery mechanism on solaris handles this. We'll run our sock program on solaris and perform one 512-byte write to the discard server on slip: solaris % sock -i -nl -w512 slip discard Figure 24.2 shows the tcpdump output, collected on the SLIP interface on the host sun. 1 0.0 solaris.33016 > slip.discard: S 1171660288:1171660288(0) win 8760 <mss 1460> (DF) file:///D|/Documents%20and%20Settings/bigini/Docum...i/homenet2run/tcpip/tcp-ip-illustrated/tcp_fut.htm (3 of 20) [12/09/2001 14.47.33] Chapter 24. TCP Futures and Performance 2 0.101597 (0.1016) 3 0.630609 (0.5290) 4 0.634433 (0.0038) 5 6 7 8 9 10 11 12 0.660331 (0.0259) 0.752664 (0.0923) 1.110342 (0.3577) 1.439330 (0.3290) 1.770154 (0.3308) 2.095987 (0.3258) 2.138193 (0.0422) 2.310103 (0.1719) slip.discard > solaris.33016: S 137984001:137984001(0) ack 1171660289 win 4096 <mss 512> solaris.33016 > slip.discard: P 1:513(512) ack 1 win 9216 (DF) bsdi > solaris: icmp: slip unreachable - need to frag, mtu = 296 (DF) solaris.33016 > slip.discard: F 513:513(0) ack 1 win 9216 (DF) slip.discard > solaris.33016: . ack 1 win 4096 solaris.33016 > slip.discard: P 1:257(256) ack 1 win 9216 (DF) slip.discard > solaris.33016: . ack 257 win 3840 solaris.33016 > slip.discard: FP 257:513(256) ack 1 win 9216 (DF) slip.discard > solaris.33016: . ack 514 win 3840 slip.discard > solaris.33016: F 1:1(0) ack 514 win 4096 solaris.33016 > slip.discard: . ack 2 win 9216 (DF) Figure 24.2 tcpdump output for path MTU discovery. The MSS values in lines 1 and 2 are what we expect. We then see solaris send a 512byte segment (line 3) containing the 512 bytes of data and the ACK of the SYN. (We saw this combination of the ACK of a SYN al...
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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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