[Netkit.users] Interface problem.-

[Massimo Rimondini]

Dear Michael,

virtual machine PC1 does not seem to be essential for the experiences 
you have proposed (ping PC2->Vrouter1, ping Vrouter1->Vrouter2, ping 
PC2->Vrouter2), hence I have been experimenting on the following 
configuration:

+------------+  +----------+  +----------+
| PC2 (real) |  | vrouter1 |  | vrouter2 |
+------+-----+  +--+----+--+  +-----+----+
       |          1|    |0          |0
       +-----------+    +-----A-----+

IP addresses:       
vrouter1
  eth0: 192.168.1.1/24
  eth1: 192.168.0.1/24 (guest side), 192.168.0.10/24 (host side)
vrouter2
  eth0: 192.168.1.2/24

I report below the outcome of the varoius ping commands, together with a 
brief explanation.

PC2 -> 192.168.0.1 (Vrouter1, eth1): succeeds

PC2 -> 192.168.1.1 (Vrouter1, eth0): fails because there is no 
corresponding entry in the host's routing table; you can fix this by 
issuing the following command on the host machine (as administrator):
route add -net 192.168.1.0/24 dev nk_tap_USERNAME

Vrouter1 -> 192.168.1.2 (Vrouter2, eth0): succeeds

PC2 -> 192.168.1.2 (Vrouter2, eth0): fails even if the host has the 
correct entry in the routing table; this happens because Vrouter1 is not 
forwarding arp requests on subnet 192.168.1.0/24; in order to fix this, 
you can enable proxy_arp inside Vrouter1 by using the following command:
echo 1 > /proc/sys/net/ipv4/conf/all/proxy_arp
This is not enough, though. Vrouter2 is now correctly receiving ICMP 
Echo Request packets but is unable to answer because subnet 
192.168.0.0/24 is not in its routing table; you can fix this by issuing 
the following command inside Vrouter2:
route add default gw 192.168.1.1
Now everything should work as expected.

Hope this helps.

Regards,
Massimo Rimondini.

maruiz a ec.gba.gov.ar wrote:

>Hi Massimo,
>
>  Yes, i have duplicate addresses, thanks, but i try many times, and cannot
>reach with ping from RealHosts to Vmachines (Pc2 to Vrouter1, and Vrouter1
>to Vrouter2 can, but cannot from Pc2 to Vrouter2)
>
> Please, if you can sendme any configuration thas has proven.
>
>Pc1(REALHOST)*--------------*Pc2(REALHOST)<->Vrouter1<->Vrouter2
>
>
>Regards,
>Michael.-
>
>
>
>
>
>>Hi Miguel,
>>
>>you seem to have duplicate IP addresses in your configuration. In fact,
>>195.11.14.5 is assigned to both vrouter1's tap interface and to pc1 (or
>>pc2).
>>
>>When you configure a tap interface, you have to specify two IP addresses:
>>- The "tap" address, which is the address of a fictitious network
>>interface on the real host (you can even see it by using ifconfig on the
>>real host). This interface serves as a connection point between vrouter1
>>and the real network. Since this is the address of a new network
>>interface, it cannot overlap with other existing addresses.
>>- The "guest" address, which is the address of a network interface
>>showing up inside the virtual machine (vrouter1).
>>
>>Uniqueness of IP addresses should however still be guaranteed.
>>
>>I suggest to remove this problem before further analyzing the issue.
>>
>>Regards,
>>Massimo.
>>
>>
>>
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