From: Rick Foltz (ccie2b@xxxxxxxxxx)
Date: Mon Aug 06 2001 - 11:10:47 GMT-3
In order to conserve IP addresses, some ISPs use private addreses for
internal links. When u send a traceroute it send the packet with a
destination address of the end target which is the public address. each time
the TTL is decreased by 1. When the routers with private addresses get the
icmp packet, they return it to you with thier address as the source. packets
are routed using the destination address, which will always be a valid
public address. you would not be able to telnet to these private addresses
at the ISP, i.e. 172.20.6.11, but they are fully capable of returning a
packet back to you.
Richard Foltz, CCNP-Voice, CCDP, MCSE+I, Network+, A+
Project Team Leader, Network Services
Smith Datacom
713-430-2184
3rd Attempt in RTP 11/2 and/or 3rd (CCIE with a * I Guess)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Leonard @ iname.com
Sent: Monday, August 06, 2001 8:20 AM
To: ccielab@groupstudy.com
Subject: Routing
Hello Guys,
I found some traceroute that really bothers me and I don't know the
answer. Would you kindly explain it to me ?
traceroute from access.net.id to 202.156.227.140
1 202.180.0.4 (202.180.0.4) 2.502 ms 2.017 ms 1.641 ms
2 202.155.7.25 (202.155.7.25) 91.019 ms 28.084 ms 30.019 ms
3 202.155.7.85 (202.155.7.85) 55.545 ms 59.557 ms 23.195 ms
4 202.155.7.246 (202.155.7.246) 62.904 ms 25.812 ms 68.068 ms
5 500.POS1-2.IG2.SAC1.ALTER.NET (157.130.193.221) 210.419 ms 210.405
ms 305.777 ms
6 0.so-0-0-0.XR2.SAC1.ALTER.NET (152.63.54.118) 240.747 ms 208.259
ms 216.579 ms
7 0.so-0-0-0.TR2.SAC1.ALTER.NET (152.63.3.197) 247.044 ms 217.252
ms 253.461 ms
8 127.ATM5-0.IR2.SAC1.ALTER.NET (152.63.11.113) 209.069 ms 226.315
ms 208.555 ms
9 POS3-0.IR2.SAC2.ALTER.NET (137.39.31.209) 204.193 ms 209.688
ms 265.266 ms
10 210.80.49.230 (210.80.49.230) 441.732 ms
335.ATM5-0-0.TR2.SIN1.ALTER.NET (210.80.51.142) 514.855 ms
435.ATM5-0-0.TR2.SIN1.ALTER.NET (210.80.51.134) 526.292 ms
11 POS1-0-0.XR2.SIN1.Alter.Net (210.80.48.62) 456.046 ms 473.853
ms 472.113 ms
12 312.ATM3-0-0.GW2.SIN1.Alter.Net (210.80.2.202) 451.268 ms 458.89
ms 434.287 ms
13 scv-gw-33.customer.alter.net (202.95.97.14) 544.822 ms 450.079
ms 460.404 ms
14 172.20.6.11 (172.20.6.11) 466.566 ms 516.396 ms 464.313 ms
15 172.20.2.15 (172.20.2.15) 458.438 ms 464.12 ms 446.679 ms
16 172.20.15.2 (172.20.15.2) 465.278 ms 476.811 ms 570.675 ms
17 mcns140.docsis227.singa.pore.net (202.156.227.140) 493.695 ms 494.196
ms 525.214 ms
If you check the entry 14-16 it is private address which is supposedly not
routeable... and it goes at entry 17 to end-host of this ISP/cable... which
is routeable address... Any idea ?
Thanks
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This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:31:46 GMT-3