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Virtual Connect Tunnel Vs. Mapping tagging example

Trusted Contributor

Virtual Connect Tunnel Vs. Mapping tagging example

Rinaldo needed some Virtual Connect  packet tagging info.




Is VC internally L2 switching when in Tunnel Mode? We’ve been asked if it operates as a hub, where every blade server sees all the traffic on the SUS and discards every frame not requested.

This could have two potential issues:

  • Security (if a blade listens interface in a promiscuous mode could watch all the traffic performed by the other blades)
  • Performance (if a server starts to strongly transmit, it could block all the others’s communication)


ARP Table: I’d say that in Mapped Mode an ARP Table is kept for each vNet inside of VC (true?).

As VC is not “VLAN aware” in Tunnel Mode it can’t have one so it acts like a hub…but there’s no mention on this on the documentation, can you please help?




Armand replied to Rinaldo:




Hi Rinaldo,


When in tunnel mode, each packet is tagged by VC on ingress, based on double-tagging standard, and untagged upon egress.

The original vlan tag is then considered as payload, and does not participate in any switching decision, while it goes through VC.


ARP table, you mean MAC table ?. VC is a layer 2 device.


Here is a picture to help:


VC Tagging.jpg




Questions or comments?