vlan routing duplicate pings

[operating]

If I ping to one of our location from our new VLAN99 I always get duplicate pings:

64 bytes from 10.44.9.51: icmp_seq=0 ttl=252 time=25.934 ms
64 bytes from 10.44.9.51: icmp_seq=0 ttl=252 time=25.939 ms (DUP!)
....

The traffic goes to a Cisco Router which is connected to the 5500G and is untagged member of VLAN1 and VLAN99. This is the way the packet goes:

4200G:

VLAN1: vlan-interface1 129.201.3.6, 255.255.0.0

Port 1,2 untagged member of VLAN1 and tagged member of VLAN99, trunk

Client Ports are untagged member of VLAN1 and VLAN99 and have PVID 99

5500G:

VLAN1: vlan-interface1 129.201.3.1, 255.255.0.0

VLAN99: vlan-interface99 10.11.3.1, 255.255.0.0

Port 1,2 untagged member of VLAN1 and tagged member of VLAN99, trunk

Default Gateway: 129.201.3.50

Cisco Router Network Settings:

129.201.3.50 AND 10.11.3.50 on the same network interface

connected to the 5500G, port hybrid, untagged member of VLAN1 and VLAN99

Client Network Settings:

IP-Address: 10.11.8.1, 255.255.0.0

Default Gateway: 10.11.3.1

The 5500G acts as a router and if I ping from a Macintosh I'll get duplicate pings but from a PC all pings are OK. This looks pretty weird to me because the PC has the same configuration as the Mac and I don't know if this is a Mac specific problem or there is something wrong with the configuration of the VLAN or maybe something else. Any help would be much appreciated!!!

[manuel.bitzi]

Hi

Hard to see the issue. the best way is to use a network sniffer (i.e. wireshark) and see where the to response come from.

By the way: Windows ping ignors the second response :-) ... but you should see it on wireshark

br

Manuel