[Xen-users] Re: Packets dropped if no ARP entry

[Peter Mellon <knascent@xxxxxxxxx>]

Okay, it turns out the problem is more simple than I thought (but I still don't know how to solve it). So ignore my previous post, here is what is happening:

On a normal kernel, successful pings shows up on tcpdump and Wireshark

On the xen kernel, successful pings do not show up on tcpdump or Wireshark. BUT, other packets like SSH connections do. 

Anyone know why this is happening?

On Wed, Jun 17, 2009 at 2:20 PM, Peter Mellon <knascent@xxxxxxxxx> wrote:

Hey everyone, I have a machine A with IP address 192.168.2.2. It is connected to another computer B that doesn't have an IP address (I'm using that computer as a bridge for another program).

 

Using a normal 2.6 kernel on B, if I ping from A to another computer on the same subnet, say '192.168.2.1', here is the output of tcpdump on B

 

[root@server5 ~]# tcpdump -i eth3

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

listening on eth3, link-type EN10MB (Ethernet), capture size 96 bytes

09:54:45.834857 arp who-has 192.168.2.1 tell 192.168.2.2

09:54:46.834858 arp who-has 192.168.2.1 tell 192.168.2.2

09:54:47.834859 arp who-has 192.168.2.1 tell 192.168.2.2

09:54:49.834856 arp who-has 192.168.2.1 tell 192.168.2.2

09:54:50.834855 arp who-has 192.168.2.1 tell 192.168.2.2

09:54:51.834855 arp who-has 192.168.2.1 tell 192.168.2.2

 

6 packets captured

6 packets received by filter

0 packets dropped by kernel

 

This is good, it is what I'm looking for. If instead I use the xen kernel on B and everything else is exactly the same, here is the output (in dom0; no virtual machines installed yet):

 

[root@server5 ~]# tcpdump -i eth3

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

listening on eth3, link-type EN10MB (Ethernet), capture size 96 bytes

 

0 packets captured

5 packets received by filter

5 packets dropped by kernel

 

As you can see, 5 packets because of the ping were received, but the xen kernel drops all of them. Anyone know how I can make the kernel accept them?

 

Thanks

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