By Chris Dyke, Sales Director UK & Ireland, Allied Telesis
https://www.alliedtelesis.com/gb/en
Almost all new devices and applications require more and more bandwidth. To understand how that challenge must be met, it can be useful to look back and map how we got to this point before evaluating how best to move forward.
Ethernet cables
Copper ethernet cable technology evolved in parallel with the ethernet standard, working on a twisted pair of copper wires and maintaining, as a constant parameter, 100m as the maximum distance covered by a point-to-point link.
The supported speed is 10Mbps over Cat3 cables, 100Mbps over Cat5 cables, 1Gbps on the Cat5e, Cat6 and Cat6e cables, and up to 10Gbps over the Cat7 cable. The standard also enables the support for 10Gbps over Cat6 and Cat6e cables with a limited distance of 55m and support for higher speed with the introduction of CAT8 cables.
Different cables come with different prices, so a Cat6 cable costs around 20% more than a Cat5 or Cat5e – and a Cat7 cable is twice as expensive.
Ethernet network
For a typical Ethernet data network composed of core, aggregation and access/edge switches, the most used technology is gigabit ethernet for the device connected to the access equipment. Multiple aggregated gigabit interfaces between the access and the aggregation and 10Gbps between aggregation and core.
Gigabit connections use copper ethernet cables but in some specific situations, typically where the distance between the access and aggregation equipment does not permit the use of copper cable, fibre is typically used. For this reason – and considering the increased cost of high-grade cables and the cost associated with the network cable upgrade – large parts of Ethernet infrastructures are still based on Cat5e and Cat6 cable, and, only in recent implementations, Cat6e or above.
Service and access devices challenges
Over the years, the use of Ethernet infrastructure has changed, and more and more devices require a network connection to work properly. Video surveillance, access control, wireless access points and many other devices rely on a wired network to provide services to organisations.
The challenge related to this evolution is that new devices and applications require more and more bandwidth but are connected to a network designed to support a fraction of the need. Taking as an example the evolution of access points, it’s easy to recognise that a legacy WiFi 4 access point’s maximum throughput is around 1Gbps, a WiFi 5 access point will support more than 2Gbps and the last released WiFi 6 more than 4Gbps. But connecting these devices to the same 1Gbps port means not being able to take advantage of the new technology speeds. At the same time, the growing diffusion of video content in almost all fields, creates another level of complexity for the whole architecture, adding pressure on the links between the access and the aggregation equipment.
For this reason, the access and aggregation equipment need to be upgraded with more capable devices and the core equipment replaced with new high-performance systems, but this solves only half the problem.
The impact on the cable infrastructure
While replacing the active equipment is relatively simple, with a limited and well-defined impact on costs and a fast implementation, it is not the same for the infrastructure.
Supporting 10Gbps on 100m requires a Cat7 cable. Cat6 or Cat6e is only enough for limited distances under 55m. In a typical installation, all the cables are shorter than 100m, but it is often hard to know if they are also shorter than 55m.
So, to have an infrastructure in line with technology evolution, the solution is to replace the whole infrastructure, changing the current cables to Cat7 cables. However, this is an expensive solution that takes a lot of time and disruption to be implemented.
The intermediate speed solution
To overcome these limitations, and at the same time enable a fast transition to a higher performant network without replacing the whole infrastructure, it is possible to rely on equipment supporting intermediate ethernet speeds between 1Gbps and 10Gbps and without replacing the passive infrastructure.
Access points, NIC cards and media converters are now available from the best providers to support 1Gbps, 2.5Gbps, and 5Gbps, and in some models also 10Gbps on the same physical interfaces. The advantage of these new intermediate rates – 2.5Gbps and 5Gbps – is the capability to use legacy infrastructure, while still maintaining the distance limitation at 100m. Look for a network infrastructure vendor that allows 2.5Gbps to be supported starting from Cat5e cable, and 5G on Cat6 cables (and limited distance over Cat5e).
With this approach, it’s possible to reuse legacy infrastructure to increase performance several times and only replace active equipment. These advantages are most evident in two specific scenarios: an access point technology upgrade and an access-aggregation link bottleneck.
Access point technology upgrade
Wireless technology becomes the main access technology in almost all scenarios, replacing copper cables in mobile devices, and a large number of modern laptops are now provided without the RJ45 Ethernet interface onboard. This progression is, at the same time, a consequence of and the reason for the exponential evolution of WiFi technology and related equipment. WiFi 4 access points, which were at the top of the technology tree a few years ago are now obsolete, replaced by WiFi 5 and then by WiFi 6, while the WiFi 7 standard is already in the pipeline. Performance improved greatly to over 1Gbps with WiFi 5 and grew again with WiFi 6 devices. When considering legacy gigabit access switches, it is necessary to aggregate two interfaces for each access point to obtain more throughput and increase the available bandwidth from 1Gbps to 2Gbps. This is the typical solution when WiFi 5 Access Points are used. For WiFi 6 access points, this is no longer enough, and the interfaces are changed from 1Gbps to 2.5Gbps and 5Gbps, enabling 5Gbps of traffic between the access point and the access switch with a single 5Gbps link or via 2x 2.5G using aggregated links.
Access-aggregation bottleneck
The increased traffic coming from the new access points, as well as other new applications and devices, dramatically increases the traffic within the access switch, so that the link between the access switch and the aggregation switch becomes the new bottleneck.
Considering a correctly dimensioned network composed of gigabit switches, the traffic between the access switches and the aggregation switches is managed with 4x1Gbps aggregated links. With the new technology, this is equivalent to the traffic generated by a single access point and is no longer enough to support the new applications.
The new generation of switches available provides multi-gigabit interfaces also on the uplink, so that (depending on the cable type and link distance) 2.5Gbps, 5Gbps or 10Gbps on the existing infrastructure can be provided. By installing these new switches, the aggregation of four links can improve throughput from the current 4Gbps to 10Gbps, 20Gbps or even 40Gbps, and this is achieved by only replacing the active devices.
The impact on other equipment
The same argument applies to any other equipment connected to the network. It is possible to upgrade almost any link by introducing a new multi-gigabit NIC card or using a multi-gigabit media converter but still using the available infrastructure.
The upgrade process
In almost any enterprise increased data rates and the desire for enhanced WiFi performance puts a lot of pressure on the IT department. To satisfy user requests, a lot of companies start to replace their current access point installations with new-generation models without taking the whole picture into account.
Replacing an access point able to support 1Gbps of traffic with a new one able to support 4Gbps of traffic and connecting it to the same 1Gbps port does not provide any practical benefit to the user. It only moves the bottleneck within the network.
The right approach for upgrading network performance – while waiting to replace all cables with Cat7 – is to start at the switches, upgrading installed ones with new multi-gigabit devices that provide the best possible throughput on current infrastructure as well as with future Cat7 infrastructure. Once the process is concluded, or in parallel with this process, replace the access points to obtain maximum benefit and always partner with a leading networking provider.
