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Networking questions [message #31491] Tue, 01 July 2008 17:54
Juan Rossi is currently offline  Juan Rossi
Messages: 1
Registered: July 2008
Junior Member
From: *mrse.com.ar
Hi 

I have a few questions about the networking internals of open vz.
We are using debian etch, for the HN and the CTs and venet for the network.
The diagram for owr network is:

-----------------------------------------------------------
| --------------------------- --------------------------- |
| | VEID 20                 | | VEID 21                 | |
| | venet0 127.0.0.1        | | venet0 127.0.0.1        | |
| | venet0:0 192.168.8.20   | | venet0:0 192.168.8.21   | |
| | venet0:1 204.200.255.20 | | venet0:1 204.200.255.21 | |
| --------------------------- --------------------------- |
|                                                         |
| eth0:0 192.168.8.12                                     |
| eth0 204.200.255.12                                     |
-----------------------------------------------------------
      |
      |             -----------------    -------------
      |-------------|GATEWAY-SWITCH |----|INTERNET   |
      |             | 204.200.255.1 |    -------------
      |             -----------------
-----------------------------------------------------------
| --------------------------- --------------------------- |
| | VEID 22                 | | VEID 23                 | |
| | venet0 127.0.0.1        | | venet0 127.0.0.1        | |
| | venet0:0 192.168.8.22   | | venet0:0 192.168.8.23   | |
| | venet0:1 204.200.255.22 | |                         | |
| --------------------------- --------------------------- |
|                                                         |
| eth0:0 192.168.8.13                                     |
| eth0 204.200.255.13                                     |
-----------------------------------------------------------
Each CT has an internal lan ip (192.168.8.0) and not always a public ip (204.200.255.0).
We have problems accessing to the different networks, that where solved adding similar route tables in each CT manually. For example for VEID 20:
route del default gw 192.0.2.1
route del -host 192.0.2.1 dev venet0
route add default gw 204.200.255.12
route add -net 192.168.8.0 netmask 255.255.255.0 gw 192.168.8.12
route add -net 204.200.255.0 netmask 255.255.255.192 gw 204.200.255.12
The first two lines are for the deletion of the FAKEGATEWAY.

Now, that I have explained myself (I hope :), here are the questions:

* Which is the function of the FAKEGATEWAY?, I couldn't find any nat in iptables for it or any documentation.
* Why in the CT venet0 has assigned 127.0.0.1 by the debian-add_ip.sh?, and why the loopback interface has it too? , Also the routing entry for 127.0.0.1 is missing.
* When I start the VE I get the following messages:
    arpsend: 192.168.8.20 is detected on another computer : 00:12:00:38:5c:45
    vps-net_add WARNING: arpsend -c 1 -w 1 -D -e 192.168.8.20 eth0 FAILED
  Extrangely when I do arping I get that the mac address is from the gateway-switch
  Is this problem related to OpenVZ configs??
* There is a better way of doing all this?
* There is more documentation aside from the wiki?, Maybe you can point me for documents that have explained all the network configs.
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