G.SHDSL Mini-PIM

This topic includes the following sections:

G.SHDSL 8–Wire Mini-PIM Overview

The G.SHDSL Mini-Physical Interface Module (Mini-PIM) is supported on SRX210 and SRX240 devices. The G.SHDSL supported on the SRX Series Services Gateways provides the physical connection to DSL network media types.

The G.SHDSL Mini-Physical Interface Module (Mini-PIM) provides the following key features:

2-wire (4 port 2-wire) mode, 4-wire (2 port 4–wire) mode, and 8-wire (1 port 8–wire) mode support
Virtual circuits per Mini-PIM (8 maximum)
ATM-over-G.SHDSL framing
ATM OAM support
Maximum MTU size of 9180 bytes
Noise margin support
Point-to-Point Protocol over ATM and PPPoE over ATM encapsulation support
Local loop back mode support

The following four annexes are supported on the G.SHDSL Mini-PIM:

Annex A
Annex B
Annex F
Annex G

Operating Modes and Line Rates of the G.SHDSL Mini-PIM

The G.SHDSL Mini-PIM supports 2-wire, 4-wire and 8-wire modes; the Mini-PIM can be used in 1x 8-wire, 2x 4- wire and 4x 2-wire modes. The default operating mode is 2x 4-wire for this G.SHDSL Mini-PIM. G.SHDSL is supported on all SRX210 and SRX240 devices using the following Symmetrical WAN speeds as shown in Table 9.

Table 9: Symmetrical WAN speeds

Modes	Symmetrical WAN Speed Using Annex A and B	Symmetrical WAN Speed Using Annex F and G
2-wire	2.3 Mbps	From 768 Kbps to 5.696 Mbps
4-wire	4.6 Mbps	From 1.536 Mbps to 11.392 Mbps
8-wire	9.2 Mbps	From 3.072 Mbps to 22.784 Mbps
Note: A maximum of 16 Mbps is supported on SRX210 and SRX240 devices.

ATM CoS Support

The G.SHDSL Mini-PIM on the SRX210 and SRX240 devices provide extended ATM CoS functionality to provides cells across the network. You can define bandwidth utilization, which consists of either a constant rate or a peak cell rate, with sustained cell rate and burst tolerance. By default, unspecified bit rate (UBR) is used because the bandwidth utilization is unlimited.

The following ATM traffic shaping is supported for the SRX210 and SRX240 devices:

Constant bit rate (CBR)—CBR is the service category for traffic with rigorous timing requirements like voice and certain types of video. CBR traffic needs a constant cell transmission rate throughout the duration of the connection.
Variable bit rate, non-real - time (VBR-NRT)—VBR-NRT is intended for sources such as data transfer, which do not have strict time or delay requirements. VBR-NRT is suitable for packet data transfers.
Variable bit rate, real- time (VBR-RT)—VBR-RT is intended for sources such as data transfer, which takes place in real time. VBR-RT requires access to time slots at a rate that can vary significantly from time to time.

Table 10 displays the traffic descriptors specified for an ATM network.

Table 10: Traffic Descriptors

Traffic Descriptors	Tasks
Peak cell rate (PCR)	Maximum rate at which traffic can burst.
Sustained cell rate (SCR)	Normal traffic rate averaged over time.
Maximum burst size (MBS)	Maximum burst size that can be sent at the peak rate.