System Performance

Cell Transfer Delay (CTD)

Switch Fabric Latency

The Cell Transfer Delay (CTD) on switching fabric + PXM1 OC-3 UNI Virtual Service Module (VSM) is on the order of 16-18 usec.

The following are timing measurements for service module boot up, softswitch and redundancy switchover for the MGX 8250 using PXM1 boards. Three types of measurement results are given in the table below:

Control Plane Outage: Time required re-establishing external control message communication with CPE or other peer nodes in the network.
Data Plane (User Plane) Outage: Time required to re-establish the user data stream.
Management Plane Outage: Time required to start accepting the new management/service provisioning requests.

References:
ms - milliseconds
Sec - seconds
0% connections - no connections. No ports, no lines, and no channels.
50% connections - 500 connections for FRSM_8T1, AUSMB_8T1, and FRSM_VHS.
96 connections for CESM_8T1.
100% connections - 1000 connections for FRSM_8T1, AUSMB_8T1, and FRSM_VHS.
192 connections for CESM_8T1.

Note Since manual intervention is needed to perform soft-switch, the Management Plane timings are unpredictable.

Note Service module boot-up times measurements are based on single-service module boot-up. During the shelf reset or if multiple service modules are booting up at the same time, the timings may vary.

Note The above measurements are made by timestamping the code. Feeder connections were made for this test. Channels were evenly spread over all lines and ports. The actual data loss in number of cells/packets was not measured.

High-Speed Frame Service Modules Switchover Timing Rates

The Hot-Standby feature reduces High-Speed FRSM switchover traffic loss to < 250 milliseconds. Refer to Table 8-1. The average traffic loss on FRSM-CT3 cards with 4000 connections has been less than 250 milliseconds. This compares to about 8 minutes of lost traffic without Hot Standby.

The service module failures were simulated by:

Resetting the card
Removing and reinserting the card

The CIR was set to 100000 bps on one of the channels, which resulted in > 100 frames/second. This was done to make sure that some traffic loss could be observed. The traffic was physically looped back through the FRSM-CT3 cards.

Table 8-1: Traffic Loss with and without Hot Standby

Number of Connections Traffic Loss without Hot Standby Traffic Loss with Hot Standby

4

31 sec

0.250 sec

2000

240 sec

0.250 sec

4000

473 sec

0.250 sec

Note All testing was done using FRSM-CT3 cards only.

Number of Connections Supported

The maximum number of connections supported by the different cards on the MGX 8250 are detailed in Table 8-2.

Table 8-2: MGX 8250 Supported Connections

Service Modules Maximum Number of HW Connections Supported

PXM1-2T3E3

32K

PXM1-4-155

32K

PXM1-1-622

32K

AX-FRSM-8T1/E1

1K (*)

AX-FRSM-2CT3

4K

AX-FRSM-2T3E3

2K

AX-FRSM-HS1/B

200

AX-FRSM-HS2

2K

AX-AUSM/B-8T1/E1

1K

AX-CESM-8T1/E1

192 (8T1) or 248 (8E1)

AX-CESM-T3E3

1

MGX-VISM-8T1/E1

240

MGX-RPM

4K

(*) = the number of connections supported per port if LMI is enabled is:
Strata LMI: 560
Annex A, Annex D for UNI and NNI: 898
Therefore, if Strata LMI is enable for all ports, total number of connection can be configured is 1120, for other LMI it would be 1996.

Number of Connections	Traffic Loss without Hot Standby	Traffic Loss with Hot Standby
4	31 sec	0.250 sec
2000	240 sec	0.250 sec
4000	473 sec	0.250 sec

Service Modules	Maximum Number of HW Connections Supported
PXM1-2T3E3	32K
PXM1-4-155	32K
PXM1-1-622	32K
AX-FRSM-8T1/E1	1K (*)
AX-FRSM-2CT3	4K
AX-FRSM-2T3E3	2K
AX-FRSM-HS1/B	200
AX-FRSM-HS2	2K
AX-AUSM/B-8T1/E1	1K
AX-CESM-8T1/E1	192 (8T1) or 248 (8E1)
AX-CESM-T3E3	1
MGX-VISM-8T1/E1	240
MGX-RPM	4K

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