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DSL traceroute packet travel

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PushPopCode

Technical User
Apr 16, 2013
3
US
Assume one has a DSL line that is in bridge mode.

One does a tracert on the modem side (anywhere and then only to the subscribers public IP address)

Does the packet end up at the DSLAM (i.e. travel over the Telco lines) and then reach the public IP address at the ISP?

Now suppose that one executes a tracert to the public IP address. Same deal?
I suspect this packet runs over the DSL telco line to the ISP's DSLAM, public IP address.

Now let's do a reverse traceroute to the subscribers public IP address.

I suspect that the packet stops at the server with the public IP address, never seeing the DSL telco line.
In other words, the packet never gets to the DSL telco line to the subscriber's modem.

Anybody with any knowledge. Thanks.


 
Most ISPs ( like in the UK here) would use BTs backbone, but all traffic is routed via a VLANs and passed through the ISPs routers in a data centre somewhere.

ACSS - SME
General Geek

 
Think of it this way:


Premise MODEM ------------------DSL LINE--------DSLAM-------public IP
(call it (1,1,1,1)------------Internet>
Ping (1,1,1,1)>>>...............................................................public IP


and

Premise MODEM ------------------DSL LINE--------DSLAM-------public IP (call it (1,1,1,1)------------Internet>
.........................................................................................public IP ..............................<<<Internet (ping (1,1,1,1)
 
[tt]If your DSL unit is configured as bridge or transparent mode, then the Ethernet device connected to it will be where the public static IP address is configured. So, if you assign IP address 1.1.1.1 to it, and tracert it or PING it from that device, then that is as far as it goes. No farther, because all you have addressed is that interface where you assigned the IP address. Unless you are addressing an address beyond that, it won't go anywhere else! This is used for troubleshooting and testing all the time... Nothing special about that... But, if the public IP address is DHCP assigned there are more steps that take place when the device is first connected to the network. After that process, it is the same as static assigned IP addresses, at least in the USA on most DSL services. There always seem to be exceptions to this stuff!

....JIM....[/tt]
 
Jim:

Thank you. I like your answer. If the public static IP is permanently assigned, then the bridge knows it.

In my case, the public IP is DHCP assigned, so therefore the packet from my LAN probably travels transparently through the modem, then "bridged to DSL" over the telco line to the DSLAM and probably "bridged" via ATM to the server handling the public IP. That server, I believe is actually in another state based on it's geolocation.

Then, in reverse, it would seem logical that the packet STOPs at the server hosting the public IP because it has no need to reach the DSL modem.

Do you agree?

The modem is also finicky, Since it;s in bridge, I can't access it at (192.168.1.1). It's been suggested that once a PPPOE connection is made, it will no longer respond (10,10,0.1). It has also been suggested that IF static routes can be added to your router, you could possibly get it to respond. A router upgrade is planned when the new ASUS Wireless ac router gets released.
 
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