PM8621-BI PMC-Sierra, Inc., PM8621-BI Datasheet - Page 31

• Manufacturer Part Number: PM8621-BI
• Description: Driver, NSE/SBS Narrowband Chipset Driver
• Manufacturer: PMC-Sierra, Inc.

Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2021248, Issue 1
For 1:N port protection (Figure 8), one logical port is reserved to protect N working ports.
Functions are available to reserve a logical port for protection purpose for a group of working
ports. At a switch over, external equipment is responsible for redirecting traffic from one of the
working ingress port to the protection port.
Figure 8: 1:N Port Protection (with N = 2) : Before and After a Switchover to Protect Working
A Ingress Port
Unidirectional Path Switching Ring (UPSR)
UPSR (Unidirectional Path Switching Ring) is supported by the chipset driver. Traffic can be
added to or dropped from a UPSR. Figure 9 illustrates a typical UPSR operation. When adding
traffic to a UPSR, the traffic is added to both the outer and inner loops (timeslots do not have to
be the same in both loops). In the case of dropping traffic from the UPSR, traffic is either sourced
from the outer or inner loop depending upon the state of the switchover. Note that the two SBS
devices associated with a UPSR have to be declared as a UPSR protection pair prior to the
add/drop operation.
Traffic can also be added to a UPSR without protection, i.e., traffic is only added to either the
outer or inner loop in a user-specified timeslot without duplicating the same traffic on the other
loop. Likewise, unprotected traffic can also be dropped from either loop. A path level switchover
is not applicable in this case.
Other Ingress
Other Ingress
Ingress Port
Ingress Port
Ingress Port
Ingress Port
Ingress Port
Ingress Port
Working A
Working B
Working A
Working B
Protection
Protection
Port
Port
Other Egress
Other Egress
Egress Port
Egress Port
Egress Port
Egress Port
Egress Port
Egress Port
Working A
Working B
Working A
Working B
Protection
Protection
Port
Port
Narrowband Chipset Device Driver Manual
Narrowband Chipset Overview
Before Switchover
After Switchover
31