Lucent Technologies 8.2 Manual De Usuario

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DEFINITY ECS Release 8.2
Administrator’s Guide  
555-233-506  
Issue 1
April 2000
Managing data calls 
427
Wideband Switching 
15
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.