ATM Traffic-Shaping Carrier Module

This chapter describes the ATM traffic-shaping carrier module (TSCAM) supported in the following systems:

Catalyst 8510 MSR
LightStream 1010 ATM

Note The ATM Traffic-Shaping Carrier Module is not supported in the Catalyst 8540 MSR, Catalyst 8540 CSR, Catalyst 8510 CSR or the Catalyst 5500. TSCAM is available on Cisco IOS Release 12.1(7a)EY or a later release of 12.1 EY.

This chapter includes the following sections:

About the ATM Traffic-Shaping Carrier Module
Hardware and Software Requirements

About the ATM Traffic-Shaping Carrier Module

The ATM traffic-shaping carrier module (TSCAM) offers the following features:

Traffic-shaping on the following port adapters:
- OC-3c
- T1
- E1
- DS3
- OC-12
Up to four TSCAMs per switch router
Online insertion and removal (OIR) of the TSCAM and the port adapters
Traffic-shaping for variable rate bit (VBR) and best-effort traffic
Traffic-shaping for a maximum of four traffic classes
Functionality for up to 32,000 virtual circuits (VCs)
An aggregate bandwidth of OC-12 (622 Mbps)

The ATM traffic-shaping carrier module (TSCAM) augments the current traffic-shaping capabilities of the Catalyst 8510 MSR switch router and the LightStream 1010 switch router by providing variable bit rate (VBR) and best-effort traffic-shaping capabilities for up to 32,000 virtual circuits with an aggregate bandwidth of one OC-12 (622 Mbps). Traffic is distributed across a maximum of four logical ports. The traffic shaper shapes the streams of cells sent over virtual circuits so that they conform to bandwidth parameters, and do not exceed the expected flow into the network. The TSCAM does this by temporarily holding cells in buffers (256K maximum), and dispersing them as bandwidth parameters allow on the outgoing connection. The TSCAM helps ensure that cells do not exceed the maximum traffic-flow parameters established between private and public networks to avoid dropping of cells.

Connections Supported

An example of how the ATM traffic-shaping carrier module might work in a network is shown in Figure 27-1. In this example, the TSCAM is in a Catalyst 8510 MSR switch router that is on the edge of a private enterprise network connected to a public ATM network. The TSCAM helps ensure that the maximum number of cells get through to the public network.

Figure 27-1: TSCAM on an Enterprise Private Network

For the T1, E1, and DS3 port adapters, a maximum of four traffic classes can be shaped. For example, if only VBR traffic is shaped, traffic-shaping for VBR can be configured on a maximum of four ports. If VBR traffic and best-effort traffic is shaped on a port, a maximum of two such ports can be configured. For the OC-3c port adapter, a maximum of three traffic classes can be shaped, and for the OC-12 port adapter, only one traffic class can be shaped.

The TSCAM occupies a full slot on the switch router and accommodates up to two port adapter modules, but traffic shaping can only be enabled on the port adapter module located in subslot 0 (Figure 27-2).

Note The capability of up to four shaped ports is available to the left port adapter module (subslot 0), while the right port adapter module (subslot 1) will always remain unshaped.

Figure 27-2: Traffic Shaping on Subslot 0 of Port Adapter Module in Slot 0

The TSCAM schedules the constant bit rate (CBR), VBR, and best-effort traffic classes in a strict priority in which CBR is the highest priority and best effort is the lowest priority. The best-effort traffic class includes UBR, available bit rate (ABR), and UBR+ service categories. When traffic-shaping is disabled for all the traffic classes on a port, all the traffic from that port is switched unaltered as if it were a single connection at the highest priority.

Any changes to shaping configurations can be supported across switch reloads only. Changes to shaping configurations can be made effective in the hardware, either by saving the configuration to NVRAM and reloading the switch or by performing online insertion and removal (OIR) of the port adapter module in subslot 0 or of the whole TSCAM.

Note Traffic-shaping in the TSCAM is disabled by default.

Note Traffic-shaping configurations do not apply to regular virtual path (VP) tunnels defined on that interface, except in the case of unspecified bit rate (UBR) VP tunnels. For example, when best-effort traffic-shaping is enabled on a physical interface, all the UBR VP tunnels defined on that interface will be shaped to their peak cell rate (PCR), but individual virtual circuits within those VP tunnels will not be shaped.

Hardware and Software Requirements

The TSCAM has several hardware and software requirements and restrictions as stated below.

Note Refer to the "Installing and Removing Modules" section for information on installing or removing a TSCAM, and port adapters. To configure your TSCAM, refer to the "Configuring the ATM Traffic-Shaping Carrier Module" chapter of the appropriate Cisco IOS Release ATM and Layer 3 Quick Software Configuration Guide.

Hardware Requirements

The following hardware requirements and restrictions apply:

Requires an ATM switch processor (ASP) with per-flow queuing feature card (ASP FC-PFQ)
Up to four TSCAMs per switch router
Online insertion and removal (OIR) of the TSCAM, and port adapters
Traffic-shaping functionality only applied to ports on subslot 0
Accommodates OC-3c, T1, E1, DS3, or OC-12 port adapters only (Refer to the appropriate port adapter chapter for cabling information.)
Not compatible with the ATM switch processor (ASP) with per-class queuing feature card (ASP FC-PCQ)

Note The TSCAM power supply operates at 27 watts, and each PAM power supply operates at 27 watts. For additional system specifications, such as dimensions and weight, refer to "ATM and Layer 3 Module Specifications".

Software Requirements

The following software restrictions apply:

Well-known VCs on an interface that are enabled for VBR traffic shaping will be shaped automatically at the maximum cell rate of that interface. Currently, there are no configurable options available to change this behavior.
Changes to shaping configurations can be made effective in the hardware, either by saving the configuration to NVRAM and reloading the switch or by performing online insertion and removal (OIR) of the port adapter module in subslot 0 or of the whole TSCAM.
TAG virtual circuits and multiprotocol label switching (MPLS) virtual circuits are not currently supported.