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All businesses are focused on return on investment, which means network operators are focused on the metro network, where at least 80% of profitable network services are created and delivered. The two most important network services -- content and mobile services -- require a metro-focused investment in infrastructure. The focus is on the cloud; software-defined networking (SDN) and network functions virtualization (NFV) will have to prove themselves in metro service applications.
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Metro area networks are integral to the two service trends -- mobile services and video content -- that define networking, now and into the future. The metro has become the proving ground for new solutions to network challenges, including SDN and NFV deployments.
By definition, mobile users are on the move. Their movements often cross mobile network cell boundaries, which is even more likely as operators move to smaller cells to reuse valuable spectrum and increase total bandwidth available to users. The explosion in cell sites has made mobile backhaul the largest consumer of fiber connections.
To support mobility, the 3GPP's IP Multimedia Subsystem (IMS) architecture defines an Evolved Packet Core (EPC) that uses tunnels from a packet service gateway to the cell site where the user is located. These tunnels are moved as users register in new cells. EPC and 3G/4G mobile infrastructure are expensive, and operators have long looked for ways to offload Internet traffic to reduce cost.
The growing issue of delivering content, particularly video, is that it requires high-capacity connections and stable quality of service. This is a difficult combination to deliver end-to-end over the Internet.
Mobile content meets CDNs
Content delivery networks (CDNs) are typically used to cache valuable or regularly accessed content copies in a metro area. The CDN decodes a content URL and directs the link to the optimum cache location, based on where the subscriber is connected. But since a mobile subscriber moves regularly, simple redirection becomes extremely complicated. Mobile SDN applications are a proposed solution to the mobile content issue.
Mobile and consumer broadband video also create a challenge for business services. Previously, most broadband was used by business customers, and business broadband connections were "one-offed" because there was no suitable infrastructure to share. Now with video and mobile backhaul driving more bandwidth deployment than carrier Ethernet, it's important to piggyback business services on metro infrastructure to gain maximum economy of scale.
Metro network critical to content delivery
Metro networks are key to next-generation content delivery for three specific reasons.
Metro networks: Where connectivity is managed. The fixed-line, last-mile connections of consumers and businesses take place in the metro network. Mobile cell roaming and subscriber management happen in the metro. Services based on customer location or customer behavior have to gather that information from the metro area where the customer is located. Whatever services the future holds, metro connections to those service points of presence will be required.
Optics and electrical connectivity come together in metro networks. Even in the access network, network operators are deploying more and deeper fiber connections, and metro aggregation is almost completely managed using optics. But the capacity of optical fiber is advancing so fast that even corporate sites may be unable to fill an entire fiber or even an entire wavelength. This means electrical grooming is an essential companion to optical transport.
Metro networks are where operations intervention and operational expenses are the highest. Customer support requires some ability to track customer experience, and service management requires specific knowledge of what services are being used and by whom. This level of personalization creates a need for highly specialized management practices, and these require the most complex operations systems, which of course are the most expensive.
The number of issues to address in metro networking has generated two distinct sets of industry reactions. Vendors like Alcatel-Lucent and Oracle have proposed integrating NFV and SDN with IMS and EPC to deliver an agile platform on which operators could build session services. The acquisition of metro-SDN-NFV player Cyan by fiber giant Ciena is likely aimed at using SDN and NFV to promote agile metro connectivity and aggregation driven by automated orchestration and management.
If over-the-top vendors that don't own their own networks follow Google's lead with Google Project Fi -- becoming mobile virtual network operators and adding features to basic voice calling -- these metro-IMS-service platforms could let operators build competitive responses. The integration of new services directly with IMS could provide operators differentiation versus OTT offerings like Google's, and even allow high-value services to be delivered through inexpensive "feature phones."
Adding SDN and NFV to opto-electrical metro network infrastructures could do more than integrate mobile/EPC and CDN functionality. It could support agile enterprise services, NFV service chaining to add features to carrier Ethernet and even cloud computing services. If NFV could orchestrate and optimize operations processes, network operators could lower their own cost base for these services so much that they could underprice OTTs and still earn a good profit.
Both of these metro evolutions are likely to be supported by larger operators, but some tier two and three operators might find only one of them attractive given their own service opportunities and current infrastructure. One or the other of these two approaches to get to the next-generation metro network might evolve more quickly than the other, either because a vendor offers stronger technology or because operator interests focus quickly on one area.
Whatever happens, the future of networking is being written in metro infrastructure now and in the future.
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