tcpdump on tap100: no packets shown, even though they arrive/get replied to

[Hugo Silva <hugo%barafranca.com@localhost>]

Hello,

Just noticed this;

15:18:05.215970 00:16:3e:be:ef:03 f2:0b:a4:63:80:03 0800 98:
172.16.99.203 > 172.16.99.133: icmp: echo request
15:18:05.216021 f2:0b:a4:63:80:03 00:16:3e:be:ef:03 0800 98:
172.16.99.133 > 172.16.99.203: icmp: echo reply

That's on machine B.

On machine A (the one replying to the ping), # tcpdump -peni tap100


tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on tap100, link-type EN10MB (Ethernet), capture size 65535 bytes



machine A is a 5.99.55 kernel+world built  Tue Aug 23 12:05:48 UTC 2011,
tap100 is on bridge3 which is passed as an interface to machine B (a Xen
domU).

Shouldn't the ping reply appear on tap100 @ the host ?

Regards,

Hugo