What Is Slowing Down Your Network and How to Fix BottlenecksGerrit Semet
It is all too easy to think that when the network becomes increasingly sluggish, that an infrastructure upgrade is needed to maintain speeds acceptable to your users.
More often than not, the problem is not that your users spend too much time downloading cat videos, but more likely that there are serious bottlenecks in the network that can and should be dealt with before bringing out the chequebook for new equipment.
Consistent slowness in the network is difficult to pinpoint and sometimes more than one problem may be occurring at the same time. It is important to start looking at a few likely suspects.
The all-too-obvious answer is to see bandwidth as the problem, but with investigation, it is often not within a LAN environment, where a high amount of bandwidth is available. More likely, the problem lies within the WAN, where capacity is more finite and expensive. Problems with slow networks in a WAN environment are more likely to result from not employing quality-of-service software.
End-to-end latency (the delay that happens to a packet end to end from the PC to the server) and any errors causing re-transmission on the network will also degrade application performance and slow the network.
Poor network performance is characterized by packet loss, which can be measured in a number of ways by using a number of different tools. Having determined that packet loss is occurring, it is necessary to understand whether this is due to a lack of buffering when traffic bursts occur, a poor queuing strategy or lack of bandwidth.
While on multiprotocol label switching (MPLS) networks, it is possible to prioritize important traffic, such as voice and video, over less important traffic such as web browsing and network backups. Even with IP QoS, it is still necessary to provision sufficient network bandwidth to avoid congestion.
When networks collide
Internet connections are increasingly becoming performance bottlenecks for organizations, mainly because of bandwidth that is not controlled properly, particularly with the increase in video streaming.
Given the most organizations have traditionally employed centrally located ISP services and firewall boundaries, perhaps a more distributed ISP branch-level set of ISP internet connections would be a possible solution for improving internet access generally for all users.
With more branch-level internet connections, internet traffic itself does not need to go directly across the corporate WAN, competing with corporate traffic on the same MPLS link. However, this throws up the problem of managing all the different network connections and ensuring that the right amount of firewall, email and web security is in place.
Another common bottleneck is between the wireless LAN controllers and the core network. This issue is likely to become more prevalent as customers move towards the latest 802.11ac wireless network implementation.
Most network bottlenecks come about because of ineffective planning and forecasting and that this is a particular challenge when a wide variety of specialized, high-touch (Layer 3 to 7) equipment is deployed deep in the big network.
Since this equipment is expensive, administrators / IT operators try not to over-provision it. However, as users become more mobile and services become more on-demand, the likelihood of spikes in resource demand and bottlenecks grows.
From a network design standpoint, it is recommended to locate these functions in a small number of larger, regionally-centralised datacentres, and using low-cost-per-bit, efficient and easily reconfigurable packet-optical transport to aggregate and express the traffic between endusers and these content centres.
If bad planning can cause bottlenecks, then perhaps it is up to network architects to design out such issues. Traditional network architectures can also take advantage of various technologies to build high-performance and load-sharing (or even load-balanced) links that provide reliable, high-performance routing of traffic and help to shape and prioritize different traffic types over the network.
Anyone running legacy networks, it might be time to consider virtualization, SDN or fabric technology, which will give the network much greater simplicity and flexibility and thus reduce the likelihood of network bottlenecks.
For example, many network professionals virtualize the network to create fewer operational overheads and add more functionality, which is win-win for the company and its users. Cutting the number of moving parts in the network enables service agility and allows the opportunity for a afaster response time for applications.
But SDN, Network Functions Virtualization (NFV) and the general move to virtualized infrastructure may hinder efforts to combat network bottlenecks. Virtualization has led to distributed applications in a datacentre, creating more east-west traffic. Transactions that were previously handled by a single host may now be split across multiple hosts in a datacentre or distributed between an on-premise host and a host located at a different location or a cloud provider.
The use of new network virtualization or SDN within a datacenter to create logical networks means issues could be hidden behind new encapsulations that the operational tools cannot decode. But we must aware that such technology brings some complexity, and the requirement to monitor and understand the “who, what, where, why and how” of the network and applications will only increase the need for comprehensive application-aware networking monitoring and historical data capture.
Network bottlenecks could become a thing of the past as embedded automation becomes part of the network. This automation would provide more self-configuration, self-attachment, automated reconfiguration with adds, moves and changes of not just applications, but servers and other devices connecting into the network.