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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.
- Understand Route Diversity
- Identify the Current Network Implementation within
Agency Control
- Interface with Carriers
- Check for Share Facilities and Communications Links
Among Service Providers
- Evaluate the Need for Backup Systems
- Seek Partner Agencies and Campuses
- Check for Enrollment and Eligibility for NCS Priority
Services
- Continue Practicing Due Diligence
- Stay Up-to-Date with Alternate and Emerging Technologies
- 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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