Lucent Technologies DEFINITY Enterprise Communications Server Release 8.2 Instructions Manual

							DEFINITY ECS Release 8.2
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Typical uses
A typical video application uses an ISDN-PRI interface to DS0 1 through 6 of the 
line-side facility. Refer to Figure 14
.
Figure Notes
Figure 14. Wideband Switching Video Application
1. Video application
2. Port 1
3. Port 2
4. ISDN terminal adaptor
5. Line-side ISDN-PRI
6. DEFINITY ECS
7. ISDN trunk8. Network
9. DS0 24 D-channel
10. DS0 23 unused
11.DS0 1–6 wideband
12. DS0 24 D-channel
13. DS0 7–23 narrow bands
14. DS0 1–6 wideband
wdbndex CJL 061996 
						

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Endpoint applications
An endpoint application is the origination or destination of a wideband call. 
Endpoint application can be any number of data applications based on the 
customer’s particular needs.
ISDN-PRI terminal adapters
For wideband switching with non-ISDN-PRI equipment, you can use an 
ISDN-PRI terminal adapter. ISDN-PRI terminal adapters translate standard ISDN 
signaling into a form that can be used by the endpoint application and vice versa. 
The terminal adapter also must adhere to the PRI-endpoint boundaries as 
administered on the DEFINITY ECS switch when handling both incoming (to the 
endpoint) applications and outgoing calls.
Line-side (T1 or E1) ISDN-PRI facility
A line-side ISDN-PRI (T1 or E1) facility is comprised of a group of DS0s (24 for 
a T1 facility and 32 for an E1 facility). In this context, these DS0s are also called 
channels. T1 facilities have 23 B-channels and a single D-channel. E1 facilities 
have 30 B-channels, 1 D-channel, and a framing channel. Data flows 
bi-directionally across the facility between the switch and the ISDN-PRI terminal 
adapter.
PRI-endpoints
A PRI-endpoint (PE) is a combination of DS0 B-channels on a line-side 
ISDN-PRI facility that has been assigned an extension. 
A PRI-endpoint can support calls of lower bandwidth. In other words, a PE having 
a width 6 (six DS0s) can handle a call of one channel (64 Kbps) up to an including 
6 channels. For example, an endpoint application connected to a PE defined as 
using B-channels 1 through 6 of an ISDN-PRI facility could originate a call using 
B-channels 1, 3, and 5 successfully. If the PE has been administered to use 
flexible channel allocation, the algorithm for offering a call to the PE starts from 
the first DS0 administered to the PE. Since only one active call is permitted on a 
PE, contiguous B-channels always are selected unless one or more B-channels are 
not in service.
One facility can support multiple separate and distinct PRI-endpoints (several 
extensions) within a single facility. Non-overlapping contiguous sets of DS0s 
(B-channels) are associated with each PE.
Universal digital signaling level 1 circuit pack
The UDS1 circuit pack is the interface for line-side and network facilities carrying 
wideband calls. 
						

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Non-signaling configuration
Wideband also can support configurations using non-signaling (non-ISDN-PRI) 
line-side T1 or E1 connections. The endpoints are the same as those defined for 
configurations with signaling.
Data service unit/channel service unit
This unit simply passes the call to the endpoint application. Unlike terminal 
adapters, the DSU/CSU does not have signaling capability.
NOTE:
No DSU/CSU is needed if the endpoint application has a fractional T1 
interface.
Line-side (T1 or E1) facility
This facility, like the ISDN-PRI facility, is composed of a group of DS0s (24 for a 
T1 facility and 32 for an E1 facility; both T1 and E1 use 2 channels for signaling 
purposes). Line-side facilities are controlled solely from the switch. Through the 
access-endpoint command, a specific DS0 or group of DS0s is assigned an 
extension. This individual DS0 or group, along with the extension, is known as a 
Wideband Access Endpoint (WAE).
Wideband access endpoint
WAEs have no signaling interface to the switch. These endpoints simply transmit 
and receive wideband data when the connection is active.
NOTE:
The switch can determine if the connection is active, but this does not 
necessarily mean that data is actually coming across the connection.
A WAE is treated as a single endpoint and can support only one call. If all DS0s 
comprising a wideband access endpoint are in service, then the wideband access 
endpoint is considered in service. Otherwise, the wideband access endpoint is 
considered out of service. If an in-service wideband access endpoint has no active 
calls on its DS0s, it is considered idle. Otherwise, the wideband access endpoint is 
considered busy.
Multiple WAEs are separate and distinct within the facility and endpoint 
applications must be administered to send and receive the correct data rate over 
the correct DS0s. An incoming call at the incorrect data rate is blocked. 
						

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Guidelines and examples
This section examines wideband and its components in relation to the following 
specific customer usage scenarios:
nData backup connection
nScheduled batch processing
nPrimary data connectivity
nNetworking
Data backup connection
Using wideband for data transmission backup provides customers with alternate 
transmission paths for critical data in the event of primary transmission path 
failure.
Scheduled batch processing
Scheduled batch processing applications are used for periodic database updates 
(for example, retail inventory) or distributions (for example, airline fare 
schedules). These updates are primarily done after business hours and are often 
referred to as nightly file transfers. Wideband meets the high bandwidth 
requirements at low cost for scheduled batch processing. In addition, wideband 
allows the dedicated-access bandwidth for busy-hour switch traffic to be used for 
these applications after business hours; no additional bandwidth costs are 
incurred.
The non-ISDN backup data connection is also appropriate for scheduled batch 
processing applications. Administered Connections are used to schedule daily or 
weekly sessions originating from this application.
Primary data connectivity
Permanent data connections (those always active during business hours), such as 
interconnections between LANs, are well suited for DEFINITY ECS when 
ISDN-PRI endpoints are used. The ISDN end-to-end monitoring and the 
endpoint’s ability to react to failures provide for critical data availability needs. 
With ISDN, endpoints can detect network failures and initiate backup connections 
through the switch; ISDN endpoints can also establish additional calls when extra 
bandwidth is needed.
Any failures not automatically restored by DEFINITY ECS are signaled to the 
endpoint application, which can initiate backup data connections over the same 
PRI endpoint. DEFINITY ECS routes the backup data connections over alternate 
facilities if necessary. 
						

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Networking
All of the wideband networking is over ISDN-PRI facilities (and the emulation of 
them by ATM-CES) but may connect to a variety of networks, other domestic 
interexchange carriers’ services, private line, RBOC services, and services in 
other countries.
ISDN-PRI trunk groups and channel
allocation
Only ISDN-PRI trunks (and the emulation of them by ATM-CES) support 
wideband calls to the network. Wideband’s bandwidth requirements have 
necessitated modification of the algorithms by which trunks look for idle 
channels. The following section describes the search methods and their 
relationship to the available wideband data services.
Facility lists
The system always sends a wideband call over a single trunk group and a single 
DS1 facility (or other ISDN-PRI-capable facility). Since a trunk group may 
contain channels (trunk members) from several different DS1 facilities, the 
system maintains a facility list for each trunk group.
A facility list orders the trunk members based on signaling group. If the system is 
using non-facility associated signaling groups with multiple DS1 facilities, the 
system sorts trunk members in that signaling group according to the interface 
identifier assigned to the corresponding DS1 facility.
When searching for available channels for a wideband call placed over a given 
trunk group, the system starts with the channels in the lowest-numbered signaling 
group with the lowest interface identifier. If the system cannot find enough 
channels in a given signaling group with that interface identifier, it checks the next 
higher interface identifier. If no more interface identifiers are available in the 
current signaling group, the system moves its search to the channels in the next 
higher signaling group.
For example, if three facilities having signaling group/interface identifier 
combinations of 1/1, 1/2, and 2/1 were associated with a trunk group, then a call 
offered to that trunk group would search those facilities in the order as they were 
just listed. Also note that since trunks within a given facility can span several 
trunk groups, a single facility can be associated with several different trunk 
groups. 
						

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Given this facility list concept, the algorithms have the ability to search for trunks, 
by facility, in an attempt to satisfy the bandwidth requirements of a given 
wideband call. If one facility does not have enough available bandwidth to 
support a given call, or it is not used for a given call due to the constraints 
presented in the following section, then the algorithm searches the next facility in 
the trunk group for the required bandwidth (if there is more than one facility in the 
trunk group).
In addition to searching for channels based on facilities and required bandwidth, 
Port Network (PN) preferential trunk routing is also employed. This PN routing 
applies within each algorithm at a higher priority than the constraints put on the 
algorithm by the parameters listed later in this section. In short, all facilities that 
reside on the same PN as the originating endpoint are searched in an attempt to 
satisfy the bandwidth of a given call, prior to searching any facilities on another 
PN.
Direction of trunk/hunting within facilities
You can tell the system to search for available channels in either ascending or 
descending order. These options help you reduce glare on the channels because 
the system can search for channels in the opposite direction to that used by the 
network. If an ISDN trunk group is not optioned for wideband, then a cyclical 
trunk hunt based on the administration of trunks within the trunk group is still 
available.
H11
When a trunk group is administered to support H11, the algorithm to satisfy a call 
requiring 1,536 Kbps of bandwidth uses a fixed allocation scheme. That is, the 
algorithm searches for an available facility using the following facility-specific 
channel definitions:
nT1: H11 can only be carried on a facility without a D-channel being 
signaled in an NFAS arrangement (B-channels 1-24 are used).
nE1: Although the 1,536 Kbps bandwidth could be satisfied using a number 
of fixed starting points (for example, 1, 2, 3, and so forth), the only fixed 
starting point being supported is 1. Hence, B-channels 1-15 and 177-25 
always are used to carry an H11 call on an E1 facility.
If the algorithm cannot find an available facility within the trunk that meets these 
constraints, then the call is blocked from using this trunk group. In this case, the 
call may be routed to a different trunk group preference via Generalized Route 
Selection (GRS), at which time, based on the wideband options administered on 
that trunk group, the call would be subject to another hunt algorithm (that is, either 
the same H11 algorithm or perhaps an N x DS0 algorithm described in a later 
paragraph). 
						

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Note that on a T1 facility, a D-channel is not considered a busy trunk and results 
in a facility with a D-channel always being partially contaminated. On an E1 
facility, however, a D-channel is not considered a busy trunk because H11 and 
H12 calls may still be placed on that facility; an E1 facility with a D-channel and 
idle B-channels is considered an idle facility.
H12
Since H12 is 1,920 Kbps which is comprised of 30 B-channels, a 1,920-kbps call 
can only be carried on an E1 facility. As with H11, the hunt algorithm uses a fixed 
allocation scheme with channel 1 being the fixed starting point. Hence, an H12 
call always is carried on B-channels 1 to 15 and 17 to 31 on an E1 facility (as 
shown in the following table). When offered any other call (other than a 
1,536-kbps call), the algorithm behaves as it does when H11 is optioned.
H0
When a trunk group is administered to support H0, the algorithm to satisfy a call 
requiring 384 Kbps of bandwidth also uses a fixed allocation scheme. Unlike the 
H11 fixed scheme which only supports a single fixed starting point, the H0 fixed 
scheme supports 4 (T1) or 5 (E1) starting points. The H0 algorithm searches for 
an available quadrant within a facility based on the direction of trunk or hunt 
administered. If the algorithm cannot find an available quadrant within any 
facility allocated to this trunk group, then the call is blocked from using this trunk 
group. Again, based on GRS administration, the call may route to a different trunk 
group preference and be subject to another algorithm based on the wideband 
options administered.
Note that a D-channel is considered a busy trunk and results in the top most 
quadrant of a T1, B-channels 19 to 24, always being partially contaminated. This 
is not true for NFAS.
If this H0 optioned trunk group is also administered to support H11, H12, or N x 
DS0, then the system also attempts to preserve idle facilities. In other words, 
when offered a narrowband, H0, or N x DS0 call, the system searches 
partially-contaminated facilities before it searches to idle facilities.
DS0s Comprising Each Channel
FacilityISDN
Interface H11 H12
T1
T123B + D
24B (NFAS)-
1-24-
-
E1
E130B + D
31B (NFAS)1-15, 17-25
1-15, 17-251-15, 17-31
1-15, 17-31 
						

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N x DS0
For the N x DS0 multi-rate service, a trunk group parameter determines whether a 
floating or a flexible trunk allocation scheme is to be used. The algorithm to 
satisfy an N x DS0 call is either floating or flexible.
nFloating (Contiguous) — In the floating scheme, an N x DS0 call is placed 
on a contiguous group of B-channels large enough to satisfy the requested 
bandwidth without any constraint being put on the starting channel (that is, 
no fixed starting point trunk).
nFlexible — In the flexible scheme, an N x DS0 call is placed on any set of 
B-channels as long as the requested bandwidth is satisfied. There is 
absolutely no constraint such as contiguity of B-channels or fixed starting 
points. Of course, as with all wideband calls, all the B-channels comprising 
the wideband call must reside on the same ISDN facility.
Regardless of the allocation scheme employed, the N x DS0 algorithm, like 
the H11 and H12 algorithms, attempts to preserve idle facilities when 
offered B, H0, and N x DS0 calls. This is important so that N x DS0 calls, 
for large values of N, have a better chance of being satisfied by a given 
trunk group. However, if one of these calls cannot be satisfied by a 
partially-contaminated facility and an idle facility exists, a trunk on that 
idle facility is selected, thus contaminating that facility.
There are additional factors to note regarding specific values of N and the 
NxDS0 service:
— N = 1 — this is considered a narrowband call and is treated as any 
other voice or narrowband-data (B-channel) call.
— N = 6 — if a trunk group is optioned for both H0 and N x DS0 
service, a 384-kbps call offered to that trunk group is treated as an 
H0 call and the H0 constraints apply. If the H0 constraints cannot be 
met, then the call is blocked.
— N = 24 — if a trunk group is optioned for both H11 and N x DS0 
service, a 1,536-kbps call offered to that trunk group is treated as an 
H11 call and the H11 trunk allocation constraints apply.
— N = 30 — if a trunk group is optioned for both H12 and N x DS0 
service, a 1,920-kbps call offered to that trunk group is treated as an 
H12 call and the H12 trunk allocation constraints apply. 
						

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Glare and blocking
Glare prevention
Glare occurs when both sides of an ISDN interface select the same B-channel for 
call initiation. For example, a user side of an interface selects the B-channel for an 
outgoing call and, before the switch receives and processes the SETUP message, 
the switch selects the same B-channel for call origination. Since any single 
wideband call uses more channels, the chances of glare are greater. With proper 
and careful administration, glare conditions can be reduced.
To reduce glare probability, the network needs to be administered so both sides of 
the interface select channels from opposite ends of facilities. This is called linear 
hunting, ascending or descending. For example, on a 23B+D trunk group, the user 
side could be administered to select B-channels starting at channel 23 while the 
network side would be administered to start selecting at channel 1. Using the same 
example, if channel 22 is active but channel 23 is idle, the user side should select 
channel 23 for re-use.
Blocking prevention
Blocking occurs when insufficient B-channels required to make a call are 
available. Narrowband calls require only one channel so blocking is less likely 
than with wideband calls which require multiple B-channels. Blocking also occurs 
for wideband calls when bandwidth is not available in the appropriate format (that 
is, fixed, floating, or flexible).
To reduce blocking, the switch selects trunks for both wideband and narrowband 
calls to maximize availability of idle fixed channels for H0, H11, and H12 calls 
and idle floating channels for N x DS0 calls that require a contiguous bandwidth. 
The strategy for preserving idle channels to minimize blocking depends on the 
channel type. The chances for blocking are reduced if you use a flexible 
algorithm, assuming it is supported on the other end.
Channel Type Blocking Minimization Strategy
H0 Preserve idle quadrants
H11 Preserve idle facilities
H12 Preserve idle facilities
Flexible NxDS0 Preserve idle facilities
Floating NxDS0 Preserve idle facilities as first priority 
						

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Administering Wideband Switching
Before you start
You need a DS1 Converter circuit pack. Refer to the DEFINITY ECS System 
Description for more information on the circuit pack.
Instructions
To administer wideband switching:
1. On the Access Endpoint screen, administer all fields. 
Refer to ‘‘
Access Endpoint’’ on page 481 for more information.
2. On the PRI Endpoint screen, administer all fields. 
Refer to ‘‘
PRI Endpoint’’ on page 865 for more information.
3. On the ISDN Trunk Group screen, administer all fields. 
Refer to ‘‘
ISDN trunk group’’ on page 750 for more information.
4. On the Route Pattern screen, administer all fields. 
Refer to ‘‘
Route Pattern’’ on page 877 for more information.
NOTE:
The following is optional.
5. On the Fiber Link Administration, administer all fields. 
Refer to DEFINITY ECS Administration for Network Connectivity for more 
information.
Considerations 
nFor wideband switching with non-ISDN-PRI equipment, you can use an 
ISDN-PRI terminal adapter.