HP Virtual Connect for the Cisco Network Administrator

HP Virtual Connect for Cisco Network Administrators (version 4.x)
Document Number: C01386629 Date: January 2014
page 22
(see Appendix A for a description of the elements in the above diagram)
Note:
Layer 2 connectivity is defined as any two devices that can communicate with each other by
directly exchanging Ethernet frames, carrying any protocol, without traversing a router or layer 3
switch. A layer 2 network could also be defined as a “broadcast domain”. For example, when a
frame is broadcast within a vNet, only ports assigned to the vNet will receive the broadcast frame
(unless an external device bridges multiple vNets together).
VC Uplink Fault Tolerance
Virtual Connect can be configured to provide both fault tolerance and load balancing for Virtual
Connect Networks and the associated server NIC ports. An Administrator can choose whether a
vNet operates in fault tolerance only mode by setting the vNet’s connection mode to “Failover” or
the Administrator can choose fault tolerance plus load balancing by setting the vNet’s connection
mode to “Auto”.
When an administrator assigns multiple VC uplinks to the same vNet, VC’s default behavior
(connection mode ‘auto’) for a vNet (or Shared Uplink Set) is to attempt to negotiate a port
channel (EtherChannel) using 802.3ad Link Aggregation Control Protocol (LACP). If LACP
negotiation fails, the vNet operates in fault tolerance mode only. Similar to the operation of NIC
Teaming, Virtual Connect will utilize one VC uplink port as the active port and all other VC
uplink ports will be in standby (blocking) mode. This behavior is part of the loop prevent mechanism
of VC (see section entitled “Virtual Connect’s Loop Prevention Technology”). See figure below
as an example.
Figure 14. A vNet Configured for Fault Tolerance only