A Quick Tracert Question

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Reelix

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Somewhere in Durban
Whilst running traceroutes to various different IP's on the hop from here to the local Google server (165.165.38.147), I found an odd peculiarity.

Code: 
C:\>tracert 196.210.130.1

Tracing route to 196-210-130-1.dynamic.isadsl.co.za [[B][U]196.210.130.1[/U][/B]]
over a maximum of 30 hops:

  1     3 ms     2 ms     2 ms  *Removed - Our Router*
  2    25 ms    17 ms    17 ms  196-210-130-1.dynamic.isadsl.co.za [[U][B]196.210.130.1[/B][/U]]
  3    60 ms    61 ms   103 ms  cdsl1-rba-vl2253.ip.isnet.net [196.38.73.181]
  4    49 ms    49 ms    43 ms  cdsl1-rba-vl150.ip.isnet.net [196.38.73.17]
  5    39 ms    40 ms    39 ms  cdsl2-rba-vl2.ip.isnet.net [196.26.77.2]
  6    27 ms    26 ms    26 ms  cdsl2-rba-vl153.ip.isnet.net [196.38.73.14]
  7    42 ms    36 ms    34 ms  cdsl2-rba-vl2765-ipc.ip.isnet.net [196.38.73.106]
  8    41 ms    38 ms    35 ms  196-210-130-1.dynamic.isadsl.co.za [[U][B]196.210.130.1[/B][/U]]

Trace complete.

C:\>

Any reason the trace doubles back on itself? Shouldn't it stop at the 2nd hop, since it arrived at its destination... ?

Tracing to the 3rd IP produces expected results.

Code: 
C:\>tracert 196.38.73.181

Tracing route to cdsl1-rba-vl2253.ip.isnet.net [196.38.73.181]
over a maximum of 30 hops:

  1    14 ms    17 ms     7 ms  *Removed - Our Router*
  2   348 ms   234 ms    18 ms  196-210-130-1.dynamic.isadsl.co.za [196.210.130.1]
  3   180 ms   101 ms    75 ms  cdsl1-rba-vl2253.ip.isnet.net [196.38.73.181]

Trace complete.

C:\>
 
Last edited:
Reelix said:
Whilst running traceroutes to various different IP's on the hop from here to the local Google server (165.165.38.147), I found an odd peculiarity.

Code: 
C:\>tracert 196.210.130.1

Tracing route to 196-210-130-1.dynamic.isadsl.co.za [[B][U]196.210.130.1[/U][/B]]
over a maximum of 30 hops:

  1     3 ms     2 ms     2 ms  *Removed - Our Router*
  2    25 ms    17 ms    17 ms  196-210-130-1.dynamic.isadsl.co.za [[U][B]196.210.130.1[/B][/U]]
  3    60 ms    61 ms   103 ms  cdsl1-rba-vl2253.ip.isnet.net [196.38.73.181]
  4    49 ms    49 ms    43 ms  cdsl1-rba-vl150.ip.isnet.net [196.38.73.17]
  5    39 ms    40 ms    39 ms  cdsl2-rba-vl2.ip.isnet.net [196.26.77.2]
  6    27 ms    26 ms    26 ms  cdsl2-rba-vl153.ip.isnet.net [196.38.73.14]
  7    42 ms    36 ms    34 ms  cdsl2-rba-vl2765-ipc.ip.isnet.net [196.38.73.106]
  8    41 ms    38 ms    35 ms  196-210-130-1.dynamic.isadsl.co.za [[U][B]196.210.130.1[/B][/U]]

Trace complete.

C:\>

Any reason the trace doubles back on itself? Shouldn't it stop at the 2nd hop, since it arrived at its destination... ?

Tracing to the 3rd IP produces expected results.

Code: 
C:\>tracert 196.38.73.181

Tracing route to cdsl1-rba-vl2253.ip.isnet.net [196.38.73.181]
over a maximum of 30 hops:

  1    14 ms    17 ms     7 ms  *Removed - Our Router*
  2   348 ms   234 ms    18 ms  196-210-130-1.dynamic.isadsl.co.za [196.210.130.1]
  3   180 ms   101 ms    75 ms  cdsl1-rba-vl2253.ip.isnet.net [196.38.73.181]

Trace complete.

C:\>
Click to expand...

Seems fine to me. On the IPC side of things, the default setup is a half-duplex MPLS VPN, which means, it knows only one way to route in that tunnel. There is also the odd chance they have PBR applied to the interface, which would force it out regardless of whether it is at it's destination or not. There could be numerous reasons for this, but most of all, it is probably to force something to work in a certain way.
 
The first tracert is the a tracert to your router gateway IP.... I guess you using an ISP with an IS backbone..
If you do a tracert to your own IP its going to go to the exchange and then back to you....

PS. you removed your local router IP but left your gateway IP address from your ISP (196.210.130.1) thats the one you should be hiding :P
 
Last edited:
Keegan said:
PS. you removed your local router IP but left your gateway IP address from your ISP (196.210.130.1) thats the one you should be hiding :P
Click to expand...
Funny why you guys think you should hide that ip. If it ends in .1 it is most probably not your actual ip, but your Point-to-Point gateway ip, which is on the Telkom ESR side, and not on the client/customer side. The actual dynamic IP will rather have anything but a .1 in the last octet.

Hiding any ip in a traceroute is pointless, unless you use the linux command tracepath, which usually include your actual ip, and that is also only if you established the pppoe session on the pc instead of from the adsl router.
 
Keegan said:
If you do a tracert to your own IP its going to go to the exchange and then back to you....
Click to expand...
A tracert to my own IP stops after 1 hop, as would be expected.

Keegan said:
PS. you removed your local router IP but left your gateway IP address from your ISP (196.210.130.1) thats the one you should be hiding :P
Click to expand...

It's their side - The 196.21 is the same, but it stops there.

Tinuva said:
Seems fine to me. On the IPC side of things, the default setup is a half-duplex MPLS VPN, which means, it knows only one way to route in that tunnel. There is also the odd chance they have PBR applied to the interface, which would force it out regardless of whether it is at it's destination or not. There could be numerous reasons for this, but most of all, it is probably to force something to work in a certain way.
Click to expand...

*Blinks* :wtf:
 
Hehe, did I say too much? Basically, unless you have major problems with your internet, you should have no worries :)
 
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