VGT Mode and untagged traffic

[zeebahi]

Hi everybody,

I was under the impression when we use VGT mode ( vlan 4095) on a standard switch, attached VMS on the standard switch, is supposed to send/receive tagged traffic.  But I see it is not necessarily true:

TEST SET UP;

CSR1-gig3-200.200.200.10/24-------PORT-GROUP: LAN , VLAN 4095  

 CRS4-gig2-200.200.200..4/24----------- |

Above we have two VMS ( Cisco CSR routers) which are configured to send/receive untagged traffic, CSR1 has gig 3 and CSR4 has gig3 in port group LAN, which has vlan id 4095.

CSR1#show running-config interface gigabitEthernet 3

Current configuration : 93 bytes
interface GigabitEthernet3
ip address 200.200.200.10 255.255.255.0

SR4#show running-config interface gigabitEthernet 2
interface GigabitEthernet2
ip address 200.200.200.4 255.255.255.0

########################################

CSR4 can ping CSR1:
CSR4#ping 200.200.200.10
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 200.200.200.10, timeout is 2 seconds:
!!!!!

Packet capture on gig 2 on CSR4 shows untagged traffic being sent out:

###############################################################

Is it a bug or expected behavior for VGT mode?

Thanks and have a good weekend!!

[scott28tt]

@zeebahi 

Moderator: Moved to vSphere vNetwork Discussions

[a_p_ · Accepted solution]

VLAN 4095 does not restrict traffic to tagged traffic only. It just allows for VGT, which means that VLAN tags will neither be added, nor removed from ingress/egress network frames by the port group. It's the guest's sole responsibility to handle the frames, i.e. send them tagged, or untagged.

André