Ethernet NIDs
_{Why they matter in edge networking}

Connectivity continues to rapidly grow across the world. The International Telecommunication Union (ITU) estimates that approximately 5.4 billion people (or 67% of the world’s population) – were using the internet as of 2023. This represents an increase of 45% since 2018, with 1.7 billion people estimated to have come online during that period. Much of this is driven by developments in wireless radio access network (RAN) technology (like 5G) – however, wired networks still have a massive part to play, accounting for a huge volume of daily traffic. And of course, there is still work to do.

In the pursuit of connectivity, service providers must be able to offer multiple services like voice, video and data to their end customers with a high level of quality assurance. Each of the services they provide is required to comply with the bandwidth and performance levels agreed with their customers. These are known as ‘Service Level Agreements’ (SLAs). To ensure such SLAs are met, service providers deploy equipment at the edge of their networks to perform service multiplexing and monitor for SLA compliance. The adherence to SLAs must be checked at the time of provisioning and on a continuous basis, so that operators can immediately correct any deviations – maintaining a high quality of service (QoS).

To do this, operators can monitor their network by installing separate test heads along with their equipment. These are a kind of Ethernet hardware ‘probe’ that connects to the network, allowing operators to remotely audit optical fibers. Alternatively, operators can reduce costs by embedding the test heads along with equipment used for providing services. Ethernet Demarcation Devices – also known as NIDs (Network Interface Devices) are hardware deployed by service providers at the edge of their networks, which are designed to do just this.

Introducing NIDS

The term ‘Ethernet’ typically describes local area networks (LANs) – for example, a private residence or company office. In contrast, ‘Carrier Ethernet’ is more capable. It’s tailored to providers that wish to service larger wide area networks (WANs), often offering additional functions, like performance guarantees. This blog outlines the features supported on Carrier Ethernet NIDs.

These NIDs connect customer equipment to the service provider’s network. They can also be deployed at the boundary between two service provider’s networks. NIDs can act as test heads, additionally serving as the end points of a service origination or termination. NIDs use a variety of techniques, along with operations, administration, and management (OAM) tools – supported by standard bodies like IEEE, ITU-T and IETF – thus ensuring that they are interoperable with a wide variety of vendor equipment.

NIDs support wire speed switching (which ensures that the switch operates at the full speed of the network, maximizing data transfer efficiency), guarantee quality of service, aid service multiplexing, and – if properly set up – don’t introduce delay or jitter when performance testing is done.

In order to provide a realistic simulation, the test traffic introduced by NIDs should emulate the test traffic from the service origination point, as well as the service termination point. Therefore, such devices are built with a combination of merchant silicon (integrated circuit chips produced by an organization other than the company selling the switches in which they are used) and proprietary hardware that satisfies both the switching and test traffic related requirements of a commercial network.

NIDS protocols and features

Edge devices like NIDs support remote configuration and management, using secure protocols like SSH or NETCONF configuration via the Simple Network Management Protocol version 3 (SNMPv3) is also supported. The IP address and management VLAN over which the devices are provisioned can be either pre-configured or can be auto discovered via the Dynamic Host Configuration Protocol (DHCP). Zero touch provisioning (ZTP) techniques – a way to configure a network where no manual intervention is required – can be used to retrieve service configuration and bandwidth profiles, thus reducing configuration cycle time for operators. NID devices also support Carrier Ethernet and Multiprotocol Label Switching (MPLS) as transport protocols – these allow applications to communicate with each other.

NIDs support flexible service tagging via either IEEE 802.1ad provider bridging or the industry supported ‘Q-in-Q’ method (AKA 802.1Q tunneling). Optionally, an additional VLAN tag can appended to transport packets over multiple service provider networks. Customer VLAN translation or tag removal can be performed before service tagging to prevent VLAN collision – a situation in which traffic from differently numbered VLANs conflicts, which can lead to intra-site communication failure. In addition, NID devices support the tunneling of Layer 2 control traffic over Ethernet services, as defined in the MEF 45.1 standard. Layer 2 is the data link layer – responsible for the reliable transmission of data frames between directly connected nodes in a network.

NIDs for quality of service

As previously mentioned, NIDs are a key way for operators to ensure that their customers are happy with the level of service. As such, NID devices support QoS configurations for each service, without which service definition would be incomplete.

Packet classification can be on a per flow basis, with flow definitions based on customer virtual local area network (VLAN), service VLAN and traffic class. Traffic class definition can be differentiated services code point (DSCP)-based for IP flows and 802.1p based for Ethernet traffic.

The QoS parameters associated with each flow include the definition of committed information rate (CIR) and excess information rate (EIR), beyond which customer traffic flows are dropped. Service metering using the MEF 10.2 standard or advanced metering using MEF 10.3 techniques with packet remarking (a form of prioritization for data) ensures that customer traffic meets SLAs.

NIDs for testing

As NIDs probe the network, they relay performance metrics to a centralized controller for data analytics. Since NIDs act as test heads, they must support both traffic initiation and the reflection of test traffic via loopback techniques – these ‘loop’ a test signal back to the sender, requiring minimal processing or modification. This not only eliminates the need for external test equipment, but also guarantees that test traffic follows the same path as customer traffic, ensuring test results are accurate. NIDs support both in service and on demand monitoring of provisioned services. The generation of test traffic used in such tests requires specialized hardware or programmable network processors which must additionally support the hardware assisted time stamping mechanism – which is used to accurately record the time of network events, for example, to maintain synchronization.

Once services are provisioned, they are monitored for SLA compliance using RFC 2544 and Y.1564 test methodologies, allowing service activation tests (SATs) before commissioning. These SATs determine whether a specific service meets performance guarantees when tested in isolation and when tested along with all configured services. Test traffic includes L2/L3 traffic with payloads of various sizes. Key metrics are measured, including Frame Loss Ratio (FLR) – which measures the number of service frames (units of data transmission) sent through the network but not received by the destination node and Frame Delay Variation (FDV) – which measures variation in the delay of these packet transmissions, expressed as video frames. RFC 2544 tests involve tests for a single service and KPIs measured include throughput, latency, jitter and frame loss.

The results, in the form of reports, are transferred to a remote controller for further analysis. In service traffic tests for continuous SLA monitoring involve Y.1731 performance monitoring (PM) and two-way active measurement protocol (TWAMP) tests. These assess traffic loss, traffic loss ratio delay and delay variation. Metrics are collected for each of the services at defined intervals and any SLA breach is reported back to the controller, so that the service provider can take appropriate action.

NIDs also support the storage of measured performance statistics and interface counters (which summarize statistics for the various interfaces on the network, eg. ethernet interfaces that connect to customer and service provider networks) as described in the MEF 35 standard – which defines OAM Performance Monitoring. These measurements, which are done on a per flow basis, are saved in storage bins in memory with support for 1 minute, 15 minute and 24 hour bins. In addition, these data can be streamed to a remote controller for further analysis. NID devices also support the remote monitoring of Ethernet statistics (on a per port basis) based on remote monitoring (RMON) v1/v2 standards. Alarms and notifications are generated whenever operator-defined thresholds are exceeded.

Build better NIDs: Introducing the Capgemini ISS framework

The Capgemini Intelligent Switch Solution (ISS) framework is a comprehensive NOS (Network Operating System) for a variety of applications using Ethernet switching, IP routing, MPLS transport, SDN (Software Defined Networking), Telemetry, Timing and Synchronization.

It supports Layer 2 Metro Ethernet services, device monitoring techniques and management protocols, and is well suited for the development of Ethernet NIDs.

Capgemini works with a variety of partners towards a competitive and vibrant ecosystem to offer the best value to the leaders and innovators in networking. As such, the framework is referenced on a variety of merchant silicon, for example, Broadcom, Realtek and Marvell, which reduces the time to market for customers planning to develop their own NID devices. In addition, Capgemini’s value added services for both hardware and software can aid you in developing NID devices with the required differentiation when using the ISS.

ISS allows you to focus on advanced network automation and service rollouts, by removing the barriers in assembling standard networking capabilities using custom designed or white box hardware. This truly disaggregated, hardware agnostic and platform agnostic architecture, proven over years in the market, provides an interoperable, mature and stable platform for you to build advanced networks with.