Hybrid networks and hybrid network infrastructure are generating a lot of buzz these days, especially in relation to cloud computing. While they sound like the same thing, they're quite different.
To differentiate between the two, first, understand the difference between a network and network infrastructure. A network is the overarching communications and data transmission environment that is composed of hardware, software, applications and transmission of data. The network infrastructure is a subset of a network and refers specifically to the hardware and physical aspects of the network, such as cabling.
What is a hybrid network?
In its simplest terms, a hybrid network describes a complete network that has elements in either multiple physical locations under different ownership or in multiple logical disciplines.
Multiple physical locations will typically imply a combination of on-premises and off-premises equipment, but the important distinction is some of the network elements are owned by an external entity. A company with offices in Chicago and Dallas does not have a hybrid network; it just has a WAN that ties together the two offices. But, if some equipment was at a colocation hosting center, an ISP or a cloud, it would be considered a hybrid network. In this sense, hybrid refers to both physical location and ownership of the network.
Today, the most common hybrid network has some elements on premises and some elements in a public cloud, which is, by default, located off premises.
However, hybrid networks have another aspect that involves clouds -- but all the equipment is in a single location. A hybrid network could be the combination of traditional legacy equipment and newer cloud equipment to create an on-premises private cloud.
In this case, hybrid describes a network composed of multiple disciplines -- traditional and cloud -- even if they sit in the same data center. One key differentiator here is the IT staff would use different tools and approaches to manage the two different networks. If a single overarching tool managed both networks, then one could argue it is not a hybrid network but instead a single entity.
What is hybrid network infrastructure?
With hybrid network infrastructure, a key differentiator is the infrastructure is a subset of an overall network. Hybrid network describes the location or discipline of the network. Hybrid network infrastructure describes multiple kinds of network infrastructure and equipment, regardless of their physical location.
Years ago, a hybrid network infrastructure might have meant different physical networks -- like Ethernet and Token Ring -- where the equipment, cabling and protocols could not interoperate. These days, Ethernet is the de facto infrastructure, handling everything from data transport to storage to voice and even video.
Still, others in the past used hybrid network infrastructure to mean equipment from multiple vendors. But this description has fallen out of favor as there's a wide array of both equipment and vendors, leading almost every data center to be multivendor by default.
Additionally, the rise of optical networking introduces a network with both optical and copper as a hybrid network infrastructure.
Today, we're more likely to hear hybrid network rather than hybrid network infrastructure, as the latter is assumed and the former is the real differentiator that people seek to quantify.