IBM SG24-4817-00 manual Connection Capacity of IBM 8285 Nways ATM Workgroup Switch

This soft copy for use by IBM employees only.

The system switching capacity maximums are listed in Table 21 on page 98 below.

Table 21. Connection Capacity of IBM 8285 Nways ATM Workgroup Switch

Maximum	IBM 8285 Base Unit
Bidirectional	-With ATM firmware upgrade kit	2,016 ￿2￿
Connections￿1￿	-Without ATM firmware upgrade kit	992
	ATM Module
	-With ATM firmware upgrade kit	2,016 ￿2￿
	-Without ATM firmware upgrade kit	992
	IBM 8285 (with Expansion Unit)
	-With ATM firmware upgrade kit	2,016 ￿3￿
	-Without ATM firmware upgrade kit	2,016
	PVCs per IBM 8285	100 ￿4￿
Maximum Multipoint Parties per IBM 8285		1,024

Notes

￿1￿ Maximum Bidirectional Connections

Defined here as the sum of point-to-point (PTP) and point-to-multipoint (PTM) connections

￿2￿ The module (CAP/CAD) is capable of supporting up to 4,064 bidirectional connections but the number is restricted to 2016 due to the 8285 ATM Control Point′s capacity (2048 PVC - 32 PVC reserved).

￿3￿ Due to the IBM 8285 control point capacity. (The number is 6,000 on the IBM 8260 A-CPSW.)

￿4￿ Sum of PtP and PtM, and also sum of PVP and PVC connections.

In the case of the 8285 switch, the transmit latency is dependent on whether the switching is done in the base unit, via CAP/CAD, or when it is installed in the IBM 8285 Expansion Chassis with its switch-on-a-chip. Table 22 shows the maximum latency for both switching modes under both normal and high utilization.

Table 22. Transmit Delay (Latency per Port)

Switching Mode	Utilization		ATM Port	Latency (in
				microseconds)
CAP/CAD	normal		25 Mbps	57 ∝s
			155 Mbps	41 ∝s
	high		25 Mbps	61 ∝s
			155 Mbps	44 ∝s
switch-on-a-chip		normal		33	∝s
		high		40	∝s

98ATM Workgroup Solutions: Implementing the 8285 ATM Switch