Unified Networking – Should I use it?

As I described in my last blog on scale out storage, I shared that scale storage is becoming synonymous with protocols such as iSCSI and NFS that can be used with regular GbE technology. Its main benefit is that it is much cheaper than legacy SAN.

Assuming that you are using or looking for storage connectivity based on CSMA/CD media access control, moving to fabric unification is almost a natural evolution. In a virtual environment where you typically have a consolidation ratio of 15-25:1, you will most likely see that a that at minimum, the total amount of bandwidth for each host must be the equivalent of the switch top-the-rack backplane, since we will have a virtual equivalent inside the hypervisor to support 15+ virtual machines plus management/maintenance activities.

In this it highly dense virtual environment, with 15-25+ virtual machines hosted on a single physical server, the network and storage traffic are concentrated and, in many cases, hosts must have as many as eight or more 1GbE interfaces plus two HBA interfaces to satisfy these requirements. Usually several port groups are configured to support the various networking functions and application grouping.


Adoption of a Unified Network, in order to allow mixing in the same media LAN and storage traffic using 10GbE, is the best way to increase flexibility – allocating bandwidth dynamically for storage and network, which is required for a cloud computing environment.

In order to archive high availability, each interface should be connected to different switches. Management traffic can be encapsulated in 10GbE or, in case CAT5/6 cabling is already in place, management traffic can also use the 1GbE interface available in the motherboard (i.e. LOM).

Even if you are convinced of the reliability of iSCSI and NFS, operating system and application compatibility, or if you just can’t throw more than one decade into SAN investment, Unified Networking is also available via FCoE (i.e. Fiber Channel over Ethernet).

Basically FCoE is an encapsulation of Fiber Channel frames over Ethernet networks. The key element in this technology is the switch, which must be FCoE compliant and support connection to SAN and LAN. Fiber channel frames usually use MTU of 9000bytes (i.e. Jumbo frame) while LAN use MTU of 1500bytes, so encapsulating requires some Ethernet protocol extension that was agreed to by the IEEE. The complete specification is available at the International Committee for Information Technology Standards.


Even for a non-virtualized environment, Unified Networking has many benefits for simplifying data center connectivity while at same time improving flexibility of resource allocation. In a few years, for a virtualized environment it will be the definitive solution.

Best Regards!

-Bruno Domingues