Network Design

Within the overall network there is often the “Optical Network Area” and the “LAN Area”. XKL is specialized in designing extremely low latency optical network equipment, hence minimizing the impact of latency at the optical network level (Layer 1).

Similarly, closer attention to the LAN network level (Layers 2/3/4) should be considered to minimize the overall latency contribution.

While the optical networking solutions may appear to be separate from the LAN Area, there are many important overlapping technologies and solutions that can reduce latency, and recover bandwidth/capacity on the overall network path as shown below.

Network Routing and Switching

The LAN Area shown above has a simple network design. In reality, there may be many different layer 2/3 devices (routers and switches) in the data path. Each layer 2/3 device adds latency to the data’s journey. Outdated routing/switching tables between network points/vLANs can add additional network connection, which is usually visible when running a traceroute between end-points, and subsequently increase latency.

Bandwidth versus Latency

The Ethernet is bandwidth intensive. A 10 gigabyte Ethernet connection may only provide a real-world data throughput of 2 to 3 gigabytes of actual data traffic. When there are multiple sources of data on the network and many different endpoints contributing to the network traffic, bandwidth becomes the main factor in additional latency for the data packets. If the data packets are buffered or lost, then they will be resent, loading the network and creating even greater contention.

From the application (and user) perspective this is a “latency” issue as it contributes to the total time it takes for the data to properly pass through the overall network path.

Mitigating Latency Within The LAN Area

It is possible to mitigate latency in the LAN area by either moving the source/destination ends closer to the fiber-optic network Area, or by increasing the available bandwidth.

Many different DWDM solutions at the fiber optic layer 1 level incorporate multiple channel ports on the device. Connecting the high-latency end-points (where possible) directly to their own channel (port) on the Transponder will ensure that there are less LAN Area devices in the data path.

Using a device like the XKL DQT10, provides each channel with its own 10G capacity that is physically separated from all other traffic crossing the fiber-optic network using other 10G channels. This helps to reduce contention by providing the high-latency data its own separate path.

The WAN’s contribution to latency should be investigated as well. Meshed layer 3 WAN with optical routers can increase latency, contrary to the simple point to point infrastructure employed at the layer 1 level. Eliminating design and routing complexity in the WAN domain will yield huge benefits and minimize the overall latency of the network.

Statistical Multiplexing

Vendors who provide statistical multiplexing (StatMux) capabilities on their devices, also provide a method of delivering more bandwidth on the fiber-segment. XKL have a StatMux solution, that actively removes the excessive Ethernet protocol packets (such as Idle packets) from the fiber segment. Removing these packets helps to add up to 2.4 times more data packets to the fiber optic path. On a 100G fiber-optic link, this has the same capacity as a 240G connection!

If you are leasing 100G service connection, it makes economic sense to use as much of the capacity as possible, and not fill the link with unnecessary empty packets. This also reduces contention for the bandwidth, and from the application (and user) perspective – a much faster, lower latency connection.

Other Sources of Latency:

Fiber Distance

The actual distance as well as the quality of the Fiber Path.

Networking Equipment

The latency introduced by the fiber networking equipment.

See XKL's full Latency Test Report