User guide

HP Virtual Connect for Cisco Network Administrators (version 4.x)
Document Number: C01386629 Date: January 2014
page 26
single link in the port channel
• Source IP address
Identifies all conversations coming from the same IP address and load balances them all down a single
link in the port channel
• Destination IP address
Identifies all conversations destined for the same IP address and load balances them all down a single
link in the port channel
• Source and Destination MAC address
Identifies all conversations between two MAC addresses and load balances them all down a
single link in the port channel
• Source and Destination IP address
Identifies all conversations between two IP addresses and load balances them all down a single
link in the port channel
• Source and Destination IP address plus TCP or UDP ports (socket)
Identifies specific conversations between two IP addresses and may load balance them down
different links in the port channel
Virtual Connect utilizes one of the last three algorithms depending on the type of frame being load
balanced.
For unicast frames, VC load balances using the socket (best method above) if it has a TCP or UDP
header, by using the source and destination IP address if it is an IP frame without a TCP or UDP
header, or by using the source and destination MAC address if it is not an IP frame.
Broadcast, multicast, and unknown unicast (destination lookup failure) frames are handled slightly
differently than unicast frames. They are load balanced so VC does not always send these frames down
the first port in the channel. The algorithm used to determine the port in the channel is based on the
source and destination MAC addresses, the source port channel number (if source is a port channel)
and/or module ID plus port number (if source is a regular port and not a port channel).
Since VC automatically load balances traffic across the ports in a port channel using the most
conversation-specific information available (TCP/UPD, then IP, then MAC), VC does not provide a
user configurable setting for this feature. Also, the load balancing algorithm does not have to match
on both sides of the same port channel. In other words, VC can use one algorithm while the directly
connected Cisco switch uses a different algorithm. Each side can implement its own algorithm
without affecting connectivity. As a result, while HP advises that the directly connect Cisco switch
utilize a load balancing algorithm based on source-destination IP plus TCP\UDP port, it is not a
requirement. If the external Cisco switch uses an algorithm based on source-destination MAC or
source-destination IP address, it will also work with Virtual Connect.
Note:
For a sample configuration showing VC uplinks connected to a Cisco switch configured for
EtherChannel, see the section below entitled “Sample Virtual Connect Ethernet and Cisco
Configurations”