WAN Glossary of Terms

This glossary provides concise definitions of common terms relating to WAN technology, including commonly used acronyms. Many definitions link to more detailed information about common applications of the technology. We regularly update the WAN glossary; so please use the form at the end if there are other terms you would like us to define.

BYOD (Bring Your Own Device): refers to the trend of employees bringing their personal mobile devices to work and connecting them to enterprise networks.  This post discusses challenges, associated with co-mingling personal and corporate information, and strategies for addressing them.

BGP (Border Gateway Protocol): used for end-to-end routing on WAN networks. It exchanges routing information between independent systems on the Internet.  When a circuit fails, BGP reroutes traffic to a secondary route, after a short delay, to prevent a complete WAN failure. Because BGP lacks application-specific intelligence, PfR may be a better alternative.

Bursting: enables network to accommodate spikes in bandwidth demand. A handful of carriers support bursting on their IP-VPN networks. Bursting can be very cost-effective because it lets customers commit to the least amount of bandwidth they need for continued use and pay for only what they use in excess of that amount.

CoS (Class of service): —enables organizations to assign some types of traffic classification priority over others. By doing so, they can get better performance out of the network without spending money on unnecessary bandwidth.  There are several Class of Service treatments for MPLS networks.

CDN (Content Delivery Network or Content Distribution Network: a large distributed system of servers deployed in multiple data centers across the internet that provide end-users with high availability and high performance.  Click here to learn more and to see a list of features that CDNs offer.

Data deduplication: the process of identifying redundant data segments and storing only one instance of information. Data deduplication dramatically reduces storage space and allows enterprises to protect more data over time.

dmarc (Demarcation Point): the location where the carrier local loop (fiber or copper) interfaces with the customer’s premise.  The carrier is responsible for installation and maintenance of wiring and equipment on one side;  the customer is responsible on the other.

DoS (Denial of service) attack: attempt to make a network resource unavailable to its users that creates a bottleneck on and greatly reduces network speeds for its duration. With a direct connection to the Internet, IP VPN over Internet is vulnerable to DoS attacks.

DRaaS (Disaster Recovery as a Service): third-party replication, hosting, and management of physical or virtual servers to provide switchover in the event of a disaster. This post outlines benefits of DRaaS.

Fast traffic switching: is the ability to switch between voice sessions quickly in the event of a disruptive event.  SDN devices need to be able to detect disruptive events and switch paths fast enough to maintain voice sessions.  Click here for more about fast traffic switching–including details about how fast is fast enough.

Firewall: Security feature that protects the VPN and terminating equipment from direct exposure to the Internet. This is one of the advantages of MPLS versus IP VPN over Internet.

Hybrid WANmultiple connection types (e.g. MPLS circuits, carrier Ethernet, internet, etc.) to deliver data to remote locations.  Organizations use hybrid WANs to save money and significantly increase bandwidth.

IEPL (International Ethernet Private Line): a true Ethernet circuit from one end to the other, IEPL enables operation of the circuit without the need for a router or CSU/DSU because the circuit is configured on the MAC address level.  The pure Ethernet circuit will provide less jitter and higher performance than the IPLC.

IPerf a simple, yet powerful tool that can provide visibility on network performance metrics such as bandwidth, latency (delay), jitter, and packet loss.

IPLC (International Private Leased Circuit): functions as a point-to-point private line.  IPLCs are usually TDM circuits that use Time Division Multiplexing to utilize the same circuit amongst many customers.  The nature

Latency: the time lapse between when data is sent and when it is received—which can have a big impact on performance. Latency is an important consideration because some applications  are particularly sensitive to latency.  It’s for these reasons that organizations typically run business class voice across MPLS   It is important to also note that the degree of latency may also differ across carriers.

Local Loop Diversity: the use of more than one access loop that enters the customer facility from a diverse location.  Best local loop diversity uses completely separate road paths to different central offices. When done correctly, can protect against disruption from failure (e.g. backhoe) in the physical link that connects the on premise demarcation point to the telecommunications provider’s network.

LTE (Long term evolution): a wireless data communication standard that uses digital signal processing (DSP) techniques to  increase the speed and capacity of wireless data networks.  LTE must be used on a separate radio spectrum because it is incompatible with 2G and 3G networks

4G: see LTE, above.

Jitter: measures delivery of packets in the proper order, which is of particular importance for VoIP. It is an important category for an MPLS Network Service Level Agreement.

MP BGP or Multiprotocol BGP or Multicast BGP  is an extension to Border Gateway Protocol (BGP) that allows different types of addresses to be distributed in parallel. While standard BGP supports only IPv4 unicast addresses, Multiprotocol BGP supports IPv4 and IPv6 addresses and it supports unicast and multicast variants of each.

MRTG: The Multi Router Traffic Grapher, or just simply MRTG, is free software for monitoring, measuring, and troubleshooting the traffic load on network links. It allows users to see traffic load on a network and bandwidth utilization over time in graphical form.

MPOE: is the Main Point of Entry where the carrier local loops enter the building.  If you need true redundancy for your access loops, your building must have two MPOEs on different sides of the building with fiber leading to a different street than the other MPOE.

MDM (Mobile Device Management): enables management of mobile devices, including employees’ own smart phones and tablets, on corporate networks.  MDM tools help the IT department manage the transition to complex mobile computing and communications environments by supporting security, network services, and software and hardware management across the many operating systems found on these devices.

Network throughput: the rate of successful message delivery. Latency, packet loss, and WAN optimization can all impact throughput and network performance.

OC (Optical Carrier) level: used to specify the speed of fiber optic networks conforming to the SONET standard. Click here for a list of speeds for common OC levels.

OOBM (Out-of-Band-Management): minimizes downtime by providing network administrators with an alternate means to access remote network devices when the primary network is down or unavailable to facilitate problem resolution.

Packet loss: occurs when one or more packets is lost in transmission. Loss of packets can disrupt applications and/or cause errors.  Lower packet losses and reduced latency are one of the reasons that organizations typically run business-class voice across MPLS services.  Packet loss is an important SLA category for an MPLS Service Level Agreement.

Packet loss correction: a technical solution that can regenerate packets on the fly. Nevertheless, there are circumstances where packet loss correction may exacerbate the problem

Peering: the voluntary connection of two separate networks so that they can exchange data for mutual benefit.  Interconnecting MPLS networks requires subject matter expertise. Network professionals must understand MPLS internals, vendor-specific switch/router implementations and carrier-specific COS markings.

PfR (Performance Routing): balances loads, and dynamically picks the best route, to optimize bandwidth use and improve network availability. For these reasons, PfR is superior to BGP.

PoE (Power over Ethernet)the ability to send power, along with data, over an Ethernet cable, to power remote devices  such as telephones, wireless access points and cameras, without the need for power cables.  

Pseudowires: an industry term for transport of any frames over an MPLS network using MPLS to encapsulate and LDP as a signaling mechanism. Pseudowires can be used to deliver two types of services to end users: virtual private wire service (VPWS) and virtual private LAN service (VPLS).

QoS (Quality of service): the level of service that results from applying Class of Service (CoS)—enables organizations to assign some types of traffic priority over others.  There are several Class of Service treatments for MPLS networks.

RPO (Recovery Point Objective): the acceptable level of data loss measured in time (i.e. 5 minutes or 4 hours) in the event of a disaster. The amount of possible data loss, measured by either data or time, will help direct the Disaster Recovery/Business Continuity solution.

RTO Recovery Time Objective): the amount of time it takes to get critical systems back into a functional state in the event of a disaster. The amount of time it takes to restore functionality will help direct the Disaster Recovery/Business Continuity solution.

Run Book: the instruction and procedure plan on how to handle Disaster Recovery/ Business Continuity scenarios.

SASESecure Access Service Edge envisions an architecture where all of the company’s entities — mobile devices, routers (sites), and cloud resources —connect to and are secured by a managed service running in the cloud.

Service Insertion:  the ability to insert Layer 4 through Layer 7 software or hardware devices in the path of endpoints, easily facilitated by SD-WAN. These services can include, to name a few: firewalls, UTM, DDoS mitigation and load balancing.

(SLA) Service Level Agreement: a contract between an organization and a service provider that spells out the agreements between the two entities such as scope, quality, and responsibilities. The specific agreements depend upon what protections are most important to the organization.  Categories for MPLS Service Level Agreements range from measures such as latency and packet loss to responsiveness of particular applications and satisfaction.

SIP (Session Initiation Protocol) trunking: enables elimination of expensive lower-speed voice and data lines by pooling them into one larger trunk. SIP trunking cost savings can be significant, as much as a 20% to 60% reduction as compared to traditional analog voice networks and packet switched data networks.

SD-WAN (Software Defined Wide Area Network): an approach to designing and deploying an enterprise wide area network (WAN) that uses software-defined networking (SDN) to determine the most effective way to route traffic to remote locations.  SD-WAN can use multiple internet circuits per location, as well as MPLS circuits.

SNMP (Simple Network Management Protocol): a popular protocol used for collecting information from and configuring network devices, such as servers, printers, hubs, switches, and routers on an Internet Protocol (IP) network.

NTOP:  a network traffic monitoring tool that enables monitoring of SNMP traffic from all your routers and is useful in troubleshooting WAN performance issues.  NTOP allows you  to use a web browser to manage and navigate through NTOP traffic information to better understand network status.

TCP (Transmission Control Protocol): is a protocol that defines how two hosts will establish a connection and exchange data. It guarantees that packets arrive in the order that they were sent.

Throughput calculator: is useful for understanding the relationship between latency, packet loss and throughput. A throughput calculator is also useful for understanding how WAN optimization can increase your WAN throughput.

Traffic Shaping: technique which delays some packets to bring them into compliance with a desired traffic profile. Traffic shaping is used to optimize or guarantee performance for some kinds of packets by delaying other kinds. Traffic shaping prevents bandwidth-hungry applications from starving the voice sessions by allocating minimum and maximum amounts of bandwidth.  VoIP and Video, for example, are typically given top and second priority over all other network traffic, in many networks.

USF (Federal Universal Service Fund ) surcharge: applies to all network charges including the network backbone, local loops, and the sale, lease, installation, and servicing of equipment. Prior to 2008, MPLS networks were not subject to the USF surcharge. As of Jan 2012, there is no escaping the USF Surcharge. Carriers can also back bill for charges owed since 2008.

VFI Identifier: specifies the VPN ID of a VPLS domain, the addresses of other PE devices in the domain, and the type of tunnel signaling and encapsulation mechanism for each peer PE device.

VPC: Virtual Private Cloud is an on-demand configurable pool of shared computing resources allocated within a public cloud environment, providing a certain level of isolation between the different organizations using the resources.

VPLS (Virtual Private LAN Service): is a technology that provides Ethernet-based multipoint communication over IP/MPLS networks. It allows geographically dispersed sites to share an Ethernet broadcast domain by connecting sites through pseudo-wires.  There are advantages and disadvantages to VPLS.

VPN (Virtual Private Network):  a method of linking two or more locations on a public network as if they are on a private network.  This post describes the pros and cons of IP VPN over Internet vs. MPLS.

VPN backup: included with IP VPN over Internet, enables switchover to another internet circuit in the event that the primary connection fails so that users can keep working. This is one of the advantages of IP VPN over Internet versus MPLS.

VPN Tunnel: is a secure path between two locations through the Internet, secured by the use of encryption.

VRF Identifier: Virtual Routing and Forwarding identifiers allow multiple isolated routing tables to exist on a single routing system.  VRFs can permit path isolation on a network.

WAN Acceleration: increases the speed of access to applications and information. WAN acceleration is also known as WAN optimization. The cloud may kill WAN optimization as more data flows through the Internet to the cloud, rather than traveling directly between two points.

WAN Optimization: increases the speed of access to applications and information. WAN optimization is also known as WAN acceleration. The cloud may kill WAN optimization as more data flows through the Internet to the cloud, rather than traveling directly between two points.

Wayleave Agreement: agreement under which a property owner gives a service provider a right to install pipe or cable passing through the owner’s property.   If a wayleave agreement is not in place, there may be delays during network installation.