On Tue, Oct 9, 2012 at 4:11 PM, Arun Khan <[email protected]> wrote: > I have seen this technique being used since the early days of consumer > ISPs (c. 1994). It is an efficient usage of a scarce resource i.e. > IPv4 numbers. > > Expect to see more and more ISPs adopting this technique within the "ISP" > cloud. > > When you traceroute to 8.8.8.8 (which is outside the ISP's cloud), you > will see the egress point from the ISP with a "public" IP number. >
I happen to have a Tata Indicom DSL service, so decided to do it myself and here is what the traceroute to 8.8.8.8 looks like: $ traceroute 8.8.8.8 traceroute to 8.8.8.8 (8.8.8.8), 30 hops max, 60 byte packets 1 172.16.0.1 (172.16.0.1) 0.371 ms 0.639 ms 0.562 ms My LAN GW (bastion host) 2 192.168.192.1 (192.168.192.1) 1.370 ms 3.781 ms 6.432 ms My ISP GW. 3 114.143.97.1 (114.143.97.1) 161.518 ms 165.061 ms 166.895 ms This is the far end of my DSL connection in the TI cloud. 4 192.168.176.9 (192.168.176.9) 45.981 ms 54.189 ms 54.546 ms Traverses through a router 192.168.176.9 in the "private IP" range within TI. 5 202.149.208.68 (202.149.208.68) 52.857 ms 56.895 ms 95.901 ms Packet goes out to the "Public" segment within TI. 6 115.113.139.233.static-lvsb.vsnl.net.in (115.113.139.233) 63.403 ms 50.644 ms 53.538 ms 7 115.113.165.98.static-mumbai.vsnl.net.in (115.113.165.98) 57.162 ms 40.019 ms 41.990 ms This is the egress point to the Internet WAN from VSNL (M&A'd with TI). 8 72.14.232.99 (72.14.232.99) 44.094 ms 40.412 ms 41.891 ms There is no in-addr.arpa PTR for above. This is most likely Google's ingress point. 9 google-public-dns-a.google.com (8.8.8.8) 44.319 ms 48.145 ms 49.922 ms the Destination IP. Interestingly, TI is honouring ICMP echo request from 192.168.176.9 $ ping 192.168.176.9 PING 192.168.176.9 (192.168.176.9) 56(84) bytes of data. 64 bytes from 192.168.176.9: icmp_req=1 ttl=252 time=45.8 ms 64 bytes from 192.168.176.9: icmp_req=2 ttl=252 time=40.6 ms 64 bytes from 192.168.176.9: icmp_req=3 ttl=252 time=39.2 ms Question: Had my LAN network address space been 192.168.176.X instead of 172.16.0.X, would I still have gotten the ping responses? -- Arun Khan _______________________________________________ Ilugd mailing list [email protected] http://frodo.hserus.net/mailman/listinfo/ilugd
