Ping problems in GNS3 VBE between VBox and a router
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Author:  ericg [ Wed Oct 05, 2011 12:32 am ]
Post subject:  Ping problems in GNS3 VBE between VBox and a router

Hi, I'm new to this forum and inexperienced with GNS3, I have just upgraded to GNS3 VBE edition and set up microcore in the latest Virtualbox, including a microcore clone with each having one network adapter attached as a host only adapter (vboxnet0).

I had problems when attaching VBox1 eth0 to router R1 interface, I could not get it to ping.

However I eventually found that on starting the VirtualBox instance in GNS3, VirtualBox had created a second interface as a UDP tunnel, this appeared on the VBox1 instance as eth1, I removed the ip address from eth0 and added an IP address to eth1 (even though I was still attached between router interface f2/0 and eth0), and lo, I could now ping the interface.

I discovered this when I checked the arp tables, VBox1 arp was incomplete, Router1 arp showed a connection to the eth1 MAC address with the eth0 ip address

Hope all that made sense, but my question is, is this the way it should be done?, have I got something misconfigured? I am quite confused over this apparent mismatch.
If no one can help me answer this, at least I hope this odd experience can help someone else get theirs going.

Secondly, it is a pain to have to constantly change IP addresses on each VBox instance and add default routes etc, is there a way to save this info like the router configs are saved?

regards to all especially the genius's who make all this possible for us.


Author:  znorris [ Wed Oct 05, 2011 1:55 am ]
Post subject:  Re: Ping problems in GNS3 VBE between VBox and a router


Good troubleshooting! Yes it is supposed to be that way. If you look at this thread: Release Notes for 0.8.1, second post...
Explanation of the concept of non-managed First NIC:
Qemu and Dynamips do not have a separate management layer.
GNS3 is the only management layer for them. Because VirtualBox has built-in
management layer, people can decide to have a back-door for their own controlled VMs.
This back-door allows admins to manage their VMs in background using first
vNIC - running scripts, doing X11 forwarding, or just have Internet access via NAT. Convenient.
If you don't need this back-door, just disconnect the VBox vCable from vNIC 1. (VM->Settings->Network)

Straight from the developers mouth. I think it does make for a less intuitive UI but I like his thought process.

I don't know if your second question is possible. If you decide to work that one out on your own be sure to let us know though.


Author:  ericg [ Wed Oct 05, 2011 5:03 am ]
Post subject:  Re: Ping problems in GNS3 VBE between VBox and a router

Good to know I wasn't nuts, thanks for the quick response Zach. I'll be sure post anything I find, but don't hold your breath, I'm not much into programming or networking, just a dumb (geriatric) noob.

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