TCP IP Illustrated

Sun netstat rn routing tables destination 1402521365

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Unformatted text preview: , since it has the dialup SLIP link that connects to the Internet (see the figure on the inside front cover). sun % netstat -rn Routing tables Destination 140.252.13.65 127.0.0.1 140.252.1.183 default 140.252.13.32 Gateway 140.252.13.35 127.0.0.1 140.252.1.29 140.252.1.183 140.252.13.33 Flags UGH UH UH UG U Refcnt 0 1 0 1 8 Use 171 766 0 2955 99551 Interface le0 lo0 sl0 sl0 le0 The first two entries are identical to the first two for the host svr4: a host-specific route to slip through the router bsdi, and the loopback route. The third line is new. It is a direct route (the G flag is not set) to a host (the H flag is set) and corresponds to our point-to-point link, the SLIP interface. If we compare it to the output from the ifconfig command, sun % ifconfig sl0 sl0: flags=1051<UP,POINTOPOINT,RUNNING> inet 140.252.1.29 -> 140.252.1.183 netmask ffffff00 we see that the destination address in the routing table is the other end of the point-to-point link (the router netb) and the gateway address is really the local IP address of the outgoing interface (140.252.1.29). (We said earlier that the gateway address printed by netstat for a direct route is the local IP address of the interface to use.) The default entry is an indirect route (G flag) to a network (no H flag), as we expect. The file:///D|/Documents%20and%20Settings/bigini/Docum...i/homenet2run/tcpip/tcp-ip-illustrated/ip_rout.htm (7 of 17) [12/09/2001 14.46.50] Chapter 9. IP Routing gateway address is the address of the router (140.252.1.183, the other end of the SLIP link) and not the local IP address of the SLIP link (140.252.1.29). Again, this is because it is an indirect route, not a direct route. We should also note that the third and fourth lines output by netstat (the ones with an interface of sl0) are created by the SLIP software being used when the SLIP line is brought up, and deleted when the SLIP link is brought down. No Route to Destination All our examples so far have assumed that the search of the routing table finds a match, even if the ma...
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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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