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#1831 - 03/21/07 11:26 AM Multiple network interfaces
Fritz Offline


Registered: 03/21/07
Posts: 4
My server has two network interfaces, both of which have paths to the Internet, but one path is one hop longer than the other. PingPlotter has been an invaluable tool for monitoring and diagnosing network problems, but I keep getting lots of route changes as it randomly switches between the two interfaces. Is there some way to force PingPlotter Standard to prefer one interface over the other? The Exclusion mask works for the first hop, but the oscillating second hop still shows up.

Fritz
Registered PPS user

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#1832 - 03/21/07 12:24 PM Re: Multiple network interfaces [Re: Fritz]
Pete Ness Offline



Registered: 08/30/99
Posts: 1106
Loc: Boise, Idaho
Hi, Fritz.

With the ICMP Raw Socket, UDP and TCP packet types, you can select an interface (by IP address) that all outgoing packets follow. This only works if the machine running PingPlotter has two actual interfaces and does its own load balancing over these interfaces.

Note that this *doesn't* work on the ICMP Default packet type, as the ICMP.DLL interface doesn't give us any way to "stick" the packets to a specific interface.

To configure this option in PingPlotter Standard, close PingPlotter Standard and open the PingPlotter.ini file (the one in your PingPlotter install directory) in your favorite text editor. Find the [Advanced] section and then add the following line in that section:

SourceAdapterAddress=192.168.1.9

Replace the 192.168.1.9 with the IP address of the adapter you want to route all data over, of course. This is the adapter address as you'd see using ipconfig, rather than the one that shows up in the PingPlotter route.

Now, restart PingPlotter and change the packet type to ICMP Raw Sockets, UDP or TCP and start tracing. You should see that all packets are using just that one interface. If you entered a wrong IP address, or there is otherwise a problem, an error message should appear above the graph area in the user interface.

If your route length changes (and routing decisions) are made outside of the machine running PingPlotter, this won't work. In that case, the only thing you can do is to change your router so that *it* makes the decision for you. Of course, I don't know anything about your router setup (and hopefully this won't be necessary), but one way people have had success here is to set up a rule on the router that looks at the DSCP byte on the packet to route over a different interface. Then, go to PingPlotter and set up that value in the DSCP field of the packet. The downside to this method, though, is that you have to configure something on the network that may be used by others, so it might not be possible depending on your network policies.

Please let us know if this addresses your issue!

- Pete

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#1833 - 03/23/07 08:27 PM Re: Multiple network interfaces [Re: Pete Ness]
Fritz Offline


Registered: 03/21/07
Posts: 4
That did it! I am using ICMP Raw. Any future route changes will be on my ISPs links. Thanks! <img src="/forums/images/graemlins/smile.gif" alt="" />

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#1834 - 04/21/07 01:29 PM Re: Multiple network interfaces [Re: Fritz]
Fritz Offline


Registered: 03/21/07
Posts: 4
ICMP raw seems to work as far as avoiding route changes, but I have noticed blocks of errors. During this period where PingPlortter can't get through, incoming HTTP and SMTP connections on the same interface are working fine, so are outgoing HTTP requests. I am switching to UDP packets to see if that clears it up.


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