Beyond Gigabit Ethernet on the LAN

Global communicationThe coming generation of enterprise Wi-Fi Access Points will allow higher than 1 Gbps sustained payload data rates between the radio interface and the wired network to which they are connected. For this reason, current LAN infrastructure, that is mostly Gigabit Ethernet over CAT5e cabling, will become the bottleneck on the LAN communications.

The alternatives to overcome this bottleneck are various, each one with its own advantages and pitfalls.

A first approach could be to move to 10 Gbps technology (10GBASE-T). This would solve today’s problem and would leave a guard gap for a mid-term increase of bandwidth needs. The problems of this approach are not only a higher cost of the infrastructure (Access Points and Switches) but mostly the need to replace current local cabling. Today over 85% of installations use CAT5e and CAT6 cables, (a classification of the LAN cables based on their quality or capacity for transmitting higher data rates), which are not able to support 10G speeds. To be more precise, CAT5e cables do not support 10G at all and CAT6 cables do support it, but only for cables up to 55 meters long, which are not enough for the majority of the cases.

Another alternative consists on the aggregation of two connections (cables) between the Access Point and the local switch. This option allows the use of today’s cheap Gigabit Ethernet switches but poses various drawbacks. That is, it requires to provision a second LAN cable to the Access Point (normally placed on hard-to-reach ceiling or wall locations), it also obliges to double the switch ports dedicated to the wireless infrastructure, and it requires to configure some level of “traffic aggregation” on the two connections between the access point and the local switch.

Ethernet at speed higher than 1 Gbps ?

Due to the limitations of the two previous approaches, a new alternative is emerging in the industry to eliminate the bottleneck. It consists on the use of Ethernet over a new physical layer, using the existing CAT5e and CAT6 cabling, that enables higher than 1 Gbps speeds.

This means that the current LAN cabling can be used to transmit Ethernet at speeds higher than 1 Gbps thanks to the use of a better physical-level transmission technology. In particular, 2.5 and 5 Gbps speeds are being considered. Besides the key objective of exceeding 1 Gbps, the new technology should also be backward compatible with 10/100/1000 remote peers (when one of the two sides of the connection still does not support the new technology) and should also support the different POE standards, to power the access point from the switch using the LAN cable.


The main advantage of this new technology is that it does not require replacing existing LAN cables, although on the negative side, new switches or switch cards supporting the new technology are needed and also the cost of such switches and the access points will be more expensive on the first wave of products, due to the “early adoption” stage.

The industry is heavily pushing towards this solution, but the lack of previous standards and technology has fragmented the market into two different and incompatible “pre-standard” technologies. NBASE-T and MGBASE-T, backed by their corresponding non-profit organizations industry alliances, are fighting for market share and adoption. Technology (silicon) vendors and end–system vendors are aligning themselves into one or the other (or the two) groups.

As the saying goes, “prediction is very difficult, especially about the future” but eventually one of the two technologies will prevail or they will both merge into a single unified standard, although until then, interoperability is just not possible.

ONT SFP GPON: End-customer solution

gpon solutionsWith the deployment of fiber to the home (FTTH), telecommunications operators put their main focus on the residential market. This is logical, since it is where there is volume and where a small increase or decrease in revenue per subscriber is converted into outstanding results on their financial accounts.

As with almost any other access technology, once the number of households with the possibility to receive the service is steadily increasing and the network is stable and running, many operators also choose to use this deployment to offer their services to the business market.

PON (passive optical network) technologies, that enable the deployment of FTTH networks in a cost-effective manner for the residential market, are evolving at a high speed. Not only as far as protocols and standards are concerned, which are constantly enabling further increases in speed, but also at “chip” level, since it manages to implement the mentioned protocols and standards in forever smaller and more efficient integrated circuits.

GPON services

Until now, to offer GPON services, currently one of the most used PON variants, the service provider had to typically install three devices at the customer’s home: (1) the “optical modem”, known in the “official” terminology as ONT, (2) the IP access router, which allows the connection of multiple devices and also typically includes a Wi-Fi access point, and optionally (3) Set-Top-Box or video decoder, if television services (IPTV) are required.

In the majority of cases, the ONT and the access router are really two different devices, when they could be only one device, as is the case with ADSL routers, which include internally an ADSL modem. Apart for using one modem in MTU (multi-user) topologies, in which several routers “hang” from one “optical modem”, this lack of integration is a sign of the lack of technological / GPON service maturity, compared for example with the mentioned ADSL technology.

An “internal type” reason for this separation between the ONT and router is due to the organizational structure within the telecom operators, whereby the ONT is considered as equipment that belongs to the operator’s own network, but located at the customer’s home, while the router is considered as customer’s network equipment and therefore managed by different departments within the operator. However, the end customer does not care and the only thing that he/she sees, is that for a FTTH service, the operator has put two boxes when the ADSL service only requires one box.

ONT GPON devices in SFP format: Convincing solution

The technological advances mentioned above are allowing the emergence of ONT devices with a SFP format (Small Form-factor Pugglable), which are normally used for other more simple optical transceivers. The SFP format allows you to provide communication equipment with fiber interfaces in a modular way, so that in a common “chassis” you can insert or connect different types of fiber. So far using the SFP ONT format devices had been residual, due to the inherent complexity of GPON and the impossibility of implementing all the necessary processing capacity into the small size of the SFP connector. It had reached the SFP ONT device market, but with a special mechanical format “backpack type”, which has consumption and heating problems.

However a new generation of chips, which have a very small size and low power consumption, is making possible the emergence of GPON ONT devices in a standard SFP format. Now the question is whether the operators will be able to organize themselves internally to transfer to the customer the advantages of a much more convenient deployment. This will indicate whether the GPON technology is “maturing”.

At Teldat we hope that this does occur, since we think that the SFP format for a GPON ONT  is a very attractive and convenient solution for the end customer, since it means a lower cost, lower consumption and the reduction or integrating of devices.

What is a wireless LAN controller and who has taken it to the cloud?

colibri serviceThe main function of a traditional wireless LAN controller (WLC ) is to configure wireless access points (AP) that connect to it locally.

However, due to the technological characteristics of a wireless area network (or Wi-Fi as it is commonly known), the traditionally used Wi-Fi network architecture and the manufacturers’ commercial strategies, a WLC carries out or can carry out many other functions, which can be grouped into the following categories:


LTE, new Connectivity Scenarios for businesses

image_LTE_catIn 2000 the GPRS technology was introduced. It offered the true possibility of transmitting data through 2G cellular networks, by adapting a circuit-switched network, designed to transmit voice, to a packet-based network. Almost a decade and a half ago, the common speed you were able to reach was 40 kbps on the downstream (from the network to the mobile terminal) and 14 kbps on the upstream (from the mobile terminal to the network).


NFV and SDN. Dumb routers for smart networks? (Network Functions Virtualization) is a new network architecture that proposes to extend the virtualization technology used in the traditional IT environment to the different network elements, to create more flexible networks and services, easier to deploy and operate, for a reduced cost. While RAID and virtualization meant a revolution on the storage technology and on the computing and operating systems technologies respectively, SDN and NFV propose an equivalent transformation on the communications networks. Cloud Computing would not have been possible without the former technologies and SDN and NFV, in turn, rely on Cloud Computing technologies to deliver their promise.

SDN (Software Defined Networking) is also an emerging network architecture that centralizes the view and control of the network, separating the forwarding decisions (control plane) from the network elements that in fact forward the packets of information (data plane), moving, in this way, the intelligence to the “center” of the network from the previously remotely distributed networks elements, like switches or routers.

SDN and NFV can exist independently of each other, but they are, in fact, complementary technologies that reinforce themselves when used simultaneously.

The interest of network operators in NFV technology

NFV is being pushed and promoted mainly by network operators, in the fight with the “Over-the-Top” service providers, which use network operators’ networks as “dumb pipes” to offer value added services and applications to the end users. With NFV, network operators seek to reduce the time to market of new services generation and provisioning, lower the required investment (CAPEX) and the operating and maintenance cost (OPEX) and expedite the innovation by favoring open-source initiatives.

NFV (and SDN) can theoretically be applied to any network element, network part, or function. For instance, it could be applied to the Mobile Core Network of a mobile operator or to the load balancer gear of a data center.

In more or less degree, part of the functionality of these network elements is subject to be virtualized and offered, for a lower cost, in a central location, using traditional low-cost COTS (Commercial Off-The-Shelf) servers running open-source based software, instead of proprietary hardware and software from established vendors. Or at least this is what many network operators are chasing, promoting and starting to test or even trial in the real world.

But, how does all this apply to the enterprise branch office access router, that is the main network element or “function” that Teldat provides? Does this specific network element have any peculiarity or characteristic that could influence or condition the way it can benefit from the NFV and SDN technologies?

Does it make sense to virtualize the access router?

A rigorous analysis falls out of the scope of this post and one will find both advantages and disadvantages when virtualizing a network element such as the access router or CPE. But regardless of the amount of functionality that might be virtualized, let us first say that we see tough to create “smarter networks” by using “dumber routers”. This does not mean that NFV does not apply to the enterprise branch office access router, but that from all the potential benefits of the NFV and SDN technologies, the CAPEX reduction is probably the less interesting one, or in other words, the toughest to obtain.

Some market initiatives, like the HGI (Home Gateway Initiative), founded in 2004, promote a model that increases the functionality of the CPE by embedding on it a “Software Execution Environment”, able to locally execute several applications or functions. This is the opposite of the NFV model regarding where to put the “intelligence”. Both architectures will probably coexist in the foreseeable future, since both have advantages and drawbacks depending on the specific use case.

The “last mile”: A challenge for NFV  application

SDN benefits are rarely questioned on the datacenter and specifically on the datacenter switches. Nevertheless, the access network and in particular the “last mile” is a much more heterogeneous environment and the bandwidth, in roughly all the cases, cannot be considered “unlimited”, as you could “model” in a Terabit/s datacenter infrastructure. Clearly this has strong implications on the NFV possibilities for a CPE.

The more complex the network element or function, the more potential NFV has to introduce benefits for the network operator. But also, the more heterogeneous the network element environment, the more complicated is to provide an equivalent “homogeneous” virtualized scenario. The last mile is a quite complex element, with non-trivial requirements such as security, quality of service, redundancy and resilience, different media adaptation, etc. On the other side, the last mile is also a quite heterogeneous scenario, especially for integrated or converged network operators that offer a broad range of access technologies.

Interoperability issues

Before a widespread adoption of SDN and NFV can occur, a crucial issue must be solved: Interoperability must be guaranteed, so that network operators do not find themselves locked into a specific vendor solution. Carriers should be warned by their experience in the GPON world with the OMCI “proprietary” management, just one fraction of the complexity NFV can imply. The open-source oriented path the network operators are proposing can be very beneficial for them, but it will not solve this interoperability problem per-se and an “integrator” figure is needed. And “integrator” or “vendor” in this regard is pretty much the same thing.

Smart routers that suit any challenge

At Teldat we follow the SDN and NFV trends with interest and we think they will definitely change the networks for good. Being a vendor that focuses on the customer premises side of the communications, we have always needed to interoperate with the network and use and promote the use of standard-based communications. Our coming devices and many of the existing ones are future proof and SDN/NFV-ready. We do this by designing smarter devices that can create smarter networks. Although some network functions can be virtualized, the enterprise branch office network in the cloud-computing era is complex enough to benefit from a powerful future-proof access router.