From: Craig Columbus (Craig.Columbus@xxxxxxxxxxxxxxxxxxxxxx)
Date: Mon Aug 06 2001 - 11:04:09 GMT-3
This thread probably belongs on the cisco mailing list, not the ccielab
mailing list. But since it's here, I'll answer.
172.20.x.x is NOT a public IP address. Refer to RFC1918. What you're
seeing are the addresses of the routers in the transit system. There are
no rules that specify that these addresses can't be private, provided that
they're not advertised. As long as the ingress and egress points know how
to get to one another, internal private addresses work fine. I've seen
both opinions, but one could make an argument that this makes the transit
network more secure since the router addresses that are visible in a trace
are not reachable from the outside world.
Craig
At 08:40 AM 8/6/2001 -0500, you wrote:
>Last time I checked, 172.20.x.x is a publicly routable address.
>
>-----Original Message-----
>From: Leonard @ iname.com [mailto:Leonard_Ong@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
>**Please read:http://www.groupstudy.com/list/posting.html
>**Please read:http://www.groupstudy.com/list/posting.html
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