Resiliency Guide

There are ten simple steps that government agencies can follow to plan and analyze route diversity and resiliency within the local access network to overcome or prevent communications outages.

1. Understand Route Diversity
2. Identify the Current Network Implementation within Agency Control
3. Interface with Carriers
4. Check for Share Facilities and Communications Links Among Service Providers
5. Evaluate the Need for Backup Systems
6. Seek Partner Agencies and Campuses
7. Check for Enrollment and Eligibility for NCS Priority Services
8. Continue Practicing Due Diligence
9. Stay Up-to-Date with Alternate and Emerging Technologies
10. Use NCS Tools, Methodologies, and Experience

For more detail on each step, download the full document or view each step below:

1. Understand Route Diversity

The first and most important step in achieving route diversity is to gain an understanding of the concept. Route diversity is communication routing between two points over more than one geographic or physical path with no common points. For example, route diversity between an agency facility and a Central Office (CO) would include physically separate points of entry or exit at the agency facility, two physically separate cabling paths to the CO, and physically separate points of entry or exit into the CO (see Example 1 in the figure below). Although the definition of route diversity does not include a standard for a separation distance, actual implementation of route diversity suggests the greater the distance of separation, the greater the benefit. For example, if the separate points of entry are next to each other, route diversity still exists (see Example 2 below); however, this may not be the best implementation of route diversity in actual practice.





Route diversity should not be confused with redundancy or resiliency. Redundancy is simply duplicate communications assets. Redundancy combined with route diversity increases resiliency, which is a network’s ability to recover from or withstand potential threats. This paper will address the topic of best practices associated with route diversity.

2. Identify the Current Network Implementation within Agency Control

The second step is to thoroughly research how communication systems are implemented at each subject facility and to identify the physical infrastructure of the supporting network. Gathering and updating this information should be the initial activity in the analysis of a communications system. Researching the communications implementation and infrastructure at a facility includes an inventory of on-site communications equipment, entry and exit points into the building, and key communication distribution points immediately outside the facility.

Personnel familiar with an agency’s voice and data communications likely can provide data associated with both government-owned and carried-owned on-site communications equipment. Such equipment is often located at critical termination points within the facility including telecommunication closets, centralized data centers, and storage locations. The personnel may also be able to provide information on the specific entry and exit points for communications into and out of the building as well as demarcation points. Demarcation points are typically located in a telephone closet and is the point where carrier equipment hands off service to the agency’s equipment. A visual inspection of the area immediately outside of a facility is often adequate to detect communications distribution points immediately outside the facility. These points are typically the location where lines running to the facility connects to a bigger local loop.

3. Interface with Carriers

Identifying and interfacing with voice and data carriers serving an agency is an important step in understanding an agency’s communications network. For example, agencies may have procured unique service terms with communications providers in the form of Service Level Agreements (SLA) based on specific requirements, including availability and incident response times. All SLAs should be collected and included in the communications infrastructure knowledge base.

In addition to information contained in SLAs, carriers are the most valuable and accurate source of information regarding the physical connectivity and locational intelligence regarding the agency’s network. A carrier’s network diagrams offer the most precise information. Combining information from all the carriers, an agency should be able to create a physical topology by determining key information. This information would include the number lines, as opposed to the number of circuits, serving the agency, the redundancy of these lines, and the subsequent locations that lines are terminating at (e.g., CO, points of presence [POP]). When considering redundancy, an agency must account for the connections to the agency’s facility rather than different carriers, as some carriers may utilize the same lines. Lines of transmission will ideally terminate at different facilities, as lines terminating at the same facility share the same risk, if said facility is rendered inoperable. To verify this data, the agency can periodically request validation of route diversity status, as carriers often “groom” circuits to balance network traffic.

Often, carriers are reluctant to divulge such information because they fear the exposed plans could pose a threat to the safety of their networks. A good practice to alleviate a carrier’s fears when requesting information is to have the following: (1) A letter outlining the intent of the data’s use and listing individuals that will have access, (2) A non-disclosure agreement (NDA) signed by those granted access to the data, (3) A documented procedure for use, storage, and access of information for anyone granted access and (4) a policy of the return of information should it be deemed necessary by the carrier (3 and 4 may or may not be included in the NDA).

4. Check for Share Facilities and Communications Links Among Service Providers

Often contracts are procured with multiple communication carriers to ensure route diversity exists in last-mile circuits. However, many agencies do not realize that contracting with multiple carriers generally does not guarantee route diverse connections. Often times, one carrier will lease lines from another carrier’s infrastructure rather than installing their own fiber lines. This could mean that an agency is being charged for service from both carriers but only using one path for all services. Conversations with carriers are thus important to gather accurate information on the locations and routes of communication service pathways outside of the facility’s campus. Information should also be collected to determine how each carrier handles routing within their network because separate communications services may converge onto single network devices in common locations, which would result in a non-route diverse path. The NCS has methodologies, tools, and experience that can assist in determining share paths and facilities in a multiple service provider environment.

5. Evaluate the Need for Backup Systems

Once agencies resolve their existing asset inventory and current infrastructure configuration they should determine if its communications systems are sufficient to accomplish its diversity requirements. If not, they should begin to develop a plan to implement solutions that address areas of concern. A typical solution is the use of backup systems. Backup systems, whether operational (hot standby) or non-operational (cold standby), provide agencies with support in terms of redundancy, and may, if procured and configured correctly, drastically increase the diversity of their communications systems. Redundancy can be offered in every area of the communications system.

Circuit redundancy provides alternate communication links from the agency facility to the carrier’s network. Additional diversity will be achieved if redundant links are configured to reside along separate pathways, terminate at separate carrier locations, or both. Secondary circuits can be used as standbys, inactive circuits or dark fiber, or as operational links providing existing services. These connections may also consist of alternative technologies besides traditional copper and fiber, such as optical beams, microwave transmission, radio frequency transmission, or satellite uplinks.

Agencies can also easily implement redundancy in support of their on-site communications equipment. Most agencies house communication equipment to handle various localized communication functions and provide outbound communication connectivity. PBX systems provide various telephone functions including voicemail, caller ID, voice conferencing, and local/long distance calling. Access routers enable local data communications functions and external information exchange functions including electronic mail, Internet connectivity, and FTP. In addition, agencies may have additional customer premise equipment such as multiplexers, patch panels, etc. All of these assets can be supported by backups. The redundancy offered increases the resiliency of the overall communications connections by greatly reducing recovery time from days to minutes or hours.

Aside from the communications assets themselves, redundancy can also be implemented to ensure the reliability and continuous operation of the support systems used to allow the communications networks to function. Communication assets are electronic devices that require safe operation environments to run effectively. The most obvious support system and possibly the more vulnerable is the electric power supply system. Agencies are often susceptible to the regional loss of electric power. This is outside the realm of an agency’s control. The addition of battery backups and local generators ensure the survivability to of communications during intermittent power surges, losses of power, or extended blackouts. The availability of backup power systems greatly increases the resiliency of the communication functions and therefore, the agency’s critical operations.

6. Seek Partner Agencies and Campuses

Agencies located in close proximity to one another hold an advantage over other agencies. These agencies have the ability to partner together to share costs and explore new ways to achieve route diversity. If agencies are close enough together, backup wireless systems can connect the facilities and be utilized in emergency situations. The two agencies then essentially become a campus. Each agency can have one service provider and still achieve route diversity, as long as each agency uses separate carriers with separate serving central offices. This type of arrangement can also save funds. Cost for the equipment can also be split across the two agencies, saving each agency money. Each agency would need to buy extra bandwidth to support the added load in an emergency situation, but the overall savings could outweigh the cost. The biannual Route Diversity Forums give agencies an opportunity to meet to explore possible options as well as discuss what is currently being done to increase route diversity. Forums and other similar events are an excellent place to make contacts at other agencies to evaluate what other agencies are currently doing to meet communication needs.

7. Check for Enrollment and Eligibility for NCS Priority Services

Many agencies are members of priority service programs for communications recovery and emergency response. The NCS provides several priority service programs for agencies and private entities in critical sectors to ensure the survivability and recovery of their communications infrastructure. For more information on these programs, see NCS priority programs.

8. Continue Practicing Due Diligence

In order to continually ensure an agency’s continuity of communications, the agency members and officials verifies current communications resiliency. This is necessary as carrier voice and data networks are constantly being changed and upgraded. A change may not be directly noticed or broadcasted, which is why at least annual reevaluation is recommended. As a result of continuously improving efficiency, carriers often groom traffic for best overall efficiency. Carriers are not always obligated to notify clients of such changes, but these modifications may be detrimental to an agency’s communications network.

In addition to keeping updated with carriers, it is valuable to continue to collect internal agency information on a regular basis. An ideal practice would be to have at least one member from related departments in the agency meet at least quarterly to update communications-related information.

9. Stay Up-to-Date with Alternate and Emerging Technologies

In addition to purchasing secondary services from a telecommunication carrier, or purchasing services from multiple telecommunication carriers, agency facilities should also consider using carriers that deploy alternative transmission mediums for their communications services. New technologies are available to complement the traditional mediums of copper wire and fiber optic cables. Free-space optics (FSO), WiMax, and satellite communications are three wireless technologies that enable a facility to enhance their resiliency by providing not just redundant communication pathways, but also pathways which are inherently more resilient to vulnerabilities common among traditional lines.

FSO systems can provide a redundant, route diverse communications link for network infrastructure to maintain critical telecommunications services when traditional local wireline facilities are rendered inoperable. FSO is a line-of-sight, point-to-point wireless transmission technology that transmits digital signals through the air over an optical path via lasers. FSO systems are able to transport voice, video, and data traffic at a capacity of up to 2.5 gigabits per second (Gbps). The ease of deployment, low component costs, and high bandwidth have made FSO a viable alternative during disaster events for applications requiring high bandwidth over short distances. However, since FSO is an optical transmission system, objects or conditions that block light may have an adverse impact on the system. Therefore, FSO is limited to installations with a clear line-of-sight between transmitter and receiver and regional weather-dependant deployable distances.

Worldwide Interoperability for Microwave Access (WiMax) is the wireless communication standard IEEE 802.16. WiMax systems are point-to-point and point-to-multipoint wireless networks that allow the transmission of data at various frequencies, licensed or unlicensed. WiMax connections can support data traffic at a capacity of 75 megabits per second (Mbps) at 20 MHz and 15-18 Mbps at 5 MHz. As a radio frequency (RF) technology, WiMax systems do not require a line-of-sight. Transmitters and receiver can operate at distances from 5 kilometers in urban areas to 20 kilometers in rural areas. Carriers are still testing WiMax and have not yet deployed these systems.

Satellite communications (SATCOM) are also a viable alternative solution to traditional wireline connections. Low earth orbit (LEO) satellites provide the global communication network with voice applications and limited data functions. Satellites connect with traditional terrestrial networks, such as the public switched voice network and the Internet, through earth stations. In addition, satellite communication technologies are available that completely bypass traditional wireline connections and networks through fixed or mobile units.

Along with FSO, WiMax, and SATCOM, other technologies have been developed as alternatives or backups to wireline communications. Technologies are constantly maturing and emerging in the marketplace. Agencies should maintain a knowledgebase of available options that may support their communication diversity and resiliency requirements. The NCS can provide guidance with current and future developments and has often completed evaluations of emerging technologies that are available for review by agencies.

10.Use NCS Tools, Methodologies, and Experience

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