Cisco Network Modules

T3/E3 ATM Network Modules for Cisco 2800, 3800 and 3900 Integrated Services Routers

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The new Cisco T3/E3 ATM Network Module (NM-1A-T3/E3) is now available for the Cisco ISR 2800, 3800 and 3900 Series Routers that provide ATM WAN connectivity for enterprise regional and branch office connectivity. This combined T3/E3 ATM network module provides an ATM connection of either 44 Mbps for DS3/T3, or 34 Mbps for E3 using standard 75-ohm BNC connectors. Support is provided for ATM Forum compliant framing standard AAL5, as well as ATM Traffic Management support for Unspecified Bit Rate (UBR), UBR+ (For SVC's only), Variable Bit Rate real-time (VBR-rt), Variable Bit Rate non-real time (VBR-nrt), Constant Bit Rate (CBR), and Available Bit Rate (ABR) classes of traffic.

The T3/E3 ATM network modules provide a cost-effective solution that can be deployed in the Cisco 2800,3800, and 3900 ISR's as Service Provider Managed customer premise equipment (CPE) or by Enterprise customers for T3/E3 and Fractional T3/E3 connectivity to medium-to-large size branch and smaller regional office locations for consolidating multiservice data, voice and video services over a single ATM link.

Figure 1. T3/E3 ATM Network Module

The following key features are supported:

• ATM Classes of Service support for: Unspecified Bit Rate (UBR), UBR+ (SVC's only), Variable Bit Rate
real-time (VBR-rt), Variable Bit Rate non-real time (VBR-nrt), Constant Bit Rate (CBR), and Available Bit Rate (ABR)

• RFC 1483 and RFC 1577 support

• 1024 maximum simultaneous Virtual Connections (VCs)

• 8 bits of VPI (VPI range 0-255), 16 bits of VCI (VCI range 0-65535)

• Permanent Virtual Circuits (PVCs) and Switched Virtual Circuits (SVCs)

• PLCP and HEC cell delineation support

• Operations and Management (F4,F5 OAM) cell support

• LANE support

• ILMI 1.0 support

• IETF PPP over ATM support

• Multiprotocol Label Swapping (MPLS) VPN support

• MPOA Client and Server

• Next Hop Routing Protocol (NHRP)

• On-line Insertion and Removal (OIR) on 3845

• Permanent Virtual Path (PVPs) support

• FRF.5/8 Interworking

• ITU-T G.703 Compliant

• ATM Traffic Management 4.1 compliant

• ATM Forum UNI 3.1/4.0 PVC compliant

• ATM Forum UNI 4.0 SVC compliant

Table 1 shows minimum Cisco IOS release and feature sets requirement for the product.

Table 1. Cisco IOS Support and Orderability Matrix for DS3/E3 ATM Network Modules


IOS S/W Version Required

IOS Feature Sets or Licenses Required

Maximum supported

Cisco 2800 Series (2811, 2821, 2851)


All Cisco IOS12.4(15)T and above "SP Services" feature sets


Cisco 3825


All Cisco 12.4(15)T and above "SP Services" feature sets


Cisco 3845


All Cisco 12.4(15)T and above "SP Services" feature sets


Cisco 3925


Data License


Cisco 3945


Data License


1Maximum recommended modules does not imply will meet performance at wire rate
2Support for the DS3/E3 ATM network module in the 3925, and 3945 will be via the network module adapter card (SM-NM-ADPTR)

Advanced Traffic Management

Advanced traffic management mechanisms in the DS3/E3 ATM network modules architecture allow for the support of bursty, client/server traffic, while supporting applications that require guaranteed or best-effort service. The ATM DS3/E3 supports all the ATM service classes, including UBR, UBR+, VBR-rt, VBR-nrt, and ABR. Supporting these ATM service classes allows the DS3/E3 network modules to concurrently support various network applications on the same ATM interface. VBR-rt is intended for applications that require guaranteed services, and ABR and UBR are intended for applications that need only "best-effort" service.
The ABR support includes the Explicit Rate (ER), Relative Rate (RR), and Explicit Forward Congestion Indicator (EFCI) modes. ABR was defined specifically to minimize cell loss and maximize good put through the ATM network. Explicit Rate ABR is typically deployed in ATM WAN switches, and is used in products such as Cisco's 8400/IGX and 8800/MGX ATM switches. Relative Rate ABR is more effectively deployed in the campus and is supported by the Cisco Lightstream 1010, and 8500 series ATM switches. EFCI is typically used for backward compatibility with legacy ATM switches that support neither Explicit nor Relative Rate. Please refer to Table 2 for ATM Service Class Definitions.

Table 2. ATM Service Class Definitions

ATM Service Classes

Typical Use

VBR-nrt-non-real time Variable Bit Rate

Used for all applications that require a level of Service guarantee through the ATM.

VBR-rt-real-time Variable Bit Rate

Used for connections that transmit at a rate varying with time and that can be described as bursty, often requiring large amounts of bandwidth when active. Intended for applications that require tightly constrained delay and delay variation such as compressed VoIP and video conferencing.

ABR-Available Bit Rate

Used to maximize bandwidth utilization on the ATM link through the use of congestion feedback notification.

UBR-Unspecified Bit Rate

Most legacy data applications using fair best-effort service.

CBR-Constant Bit Rate

Provides guaranteed bandwidth for data applications such as SNA traffic.

Per-VC Traffic Shaping

Traffic shaping is a function typically provided on ATM edge devices to ensure that bursty traffic conforms to a predetermined Service Level Agreement (SLA). More specifically, traffic shaping ensures that traffic from one VC does not adversely impact another, resulting in data loss. This function is very important when connecting to an ATM WAN or public ATM network-especially when the ATM switches enable traffic policing that will discard all traffic that exceeds the predetermined contract at the ingress of the switch.
The ATM DS3/E3 supports traffic shaping in hardware which eliminates performance degradation when shaping is enabled. Providing traffic shaping on a per-VC basis in done by the software using IP-to-ATM CoS mapping feature and allows total flexibly and control over every VC configured.
For each ATM service class, the ATM DS3/E3 supports highly configurable parameters: peak cell rate (PCR), sustainable cell rate (SCR), maximum burst size (MBS) and minimum cell rate (MCR). These parameters can be defined based on the specific bandwidth requirements of an individual VC, as needed for a specific application. Table 3 lists ATM Class of Service Traffic Shaping Parameters supported on the product.

Table 3. ATM Class of Service Traffic Shaping Parameters

VBR -rt and nrt Parameters

ABR Parameters

UBR Parameters

PCR (kbps)

PCR (kbps)

PCR (kbps)

SCR (kbps)

MCR (kbps


MBS (cells)



The ATM DS3/E3 hardware "shapes" the VC to the specific parameters using a wheel-based scheduling algorithm to ensure fairness across the ATM interface. In the event that two cells compete for the same time slot, the VCs are prioritized in the following order (starting with highest priority): 1) CBR; 2)rt-VBR; 3)nrt-VBR; 3) ABR; and 4) UBR. OAM cells and signaling has the priority higher than any of the service classes. Prioritizing the VCs in this manner ensures that the high priority and guaranteed traffic have precedence over the best-effort traffic.
To provide further flexibility, the ATM DS3/E3 allows each of these parameters to be set over a wide range of small increments. Please refer to Table 4 for the Traffic Shaping Granularity supported on this module.

Table 4. Traffic Shaping Granularity





64 kbps to line rate

64 kbps


64 kbps to line rate

64 kbps


• <32 up to 4 Mbps
• <200 up to line rate

One cell

Note: Although configuration to line rate is allowed, line rate is only reached with large packet sizes.

Extended Virtual Connections Capabilities

The ATM DS3/E3 supports up to 1024 Virtual Connections (VC) and up to 256 Virtual Path (VP). Any combinations of VC and VP can be supported up to a maximum number of 1024 VC/VP combinations. These VCs can be either Permanent Virtual Connections (PVC) which are created manually or Switched Virtual Connections (SVC) created through point-to-point and point-to-multipoint UNI signaling. Table 5 provides Interface Specification details. Table 6 provides LED Indicator description.

Table 5. Interface Specifications



Connector Type


Maximum Distance


44.736 Mbps



450 ft.


34.368 Mbps



1250 ft.

Note: The DS-3 version provides adaptive equalization for 0-450 ft. of cable and provides loopback capability. The E3 version provides adaptive equalization for 0-1250 ft. of cable and also provides loopback capabilities. The DS-3 version also has the ability to support line build-out for cable lengths of less than 50 ft. or greater than 50 ft., as required.

Table 6. LED Indicators


Port Status




Indicates the ATM NM is successfully inserted and has established communications to the PCI bus. It is ready to accept CLI commands



Indicates that a receive clock has been detected



The framer has detected a Far End Receive Failure



The framer has detected an Out of Frame occurrence



The framer has detected an Alarm Indication Signal

System Requirements

• A maximum of one NM-1A-T3/E3 Network Module is supported on the Cisco 2811,2821,2851 and 3845. Two are supported on the Cisco 3845. Line rate performance is not guaranteed for maximum NM-1A-T3/E3 Network Module support on the platforms.

• Operates in conjunction with all currently available Cisco 3800 network modules and WAN interface cards (WICs) and with all currently available Cisco 3900 Network Modules, Service Modules, Internal Services Modules, EHWICs, HWICs, WICs and VICs.

• No slot placement restrictions

• Support for the DS3/E3 ATM network module in the 3925, and 3945 will be via the network module adapter card (SM-NM-ADPTR).

Network Management

Supported MIBs include:

• Synchronous Optical Network (SONET) MIB


• AToM MIB (FRC 1695)





• LAN Emulation (LANE) MIB

• Cisco-AAL5-MIB


Product Compliance Standards

The DS-3 and E3 ATM network modules are to receive all the agency approvals necessary for unlimited international availability. The following regulatory approvals are supported:


Table 7. DS3/E3 ATM Physical Specifications

Product Specifications


Dimensions (H x W x D)

1.55 x 7.10 x 7.2 in


2 lbs. Maximum

Environmental Conditions

• Operating temp. 41-131°F (+5 -+55°C)
• Non-operating temp. -13-158°F (-25-70°C)

Relative Humidity

0 to 90%, noncondensing


Class B EMI


75 Ohm BNC type connector


Enabled, RX cells, RX carrier, RX Alarm

Safety Regulatory Approvals

• UL 1950 3rd edition/CSA C22.2, no. 950

• C1950 (Canada)

• AS/NZS 3260 (Australia/New Zealand)

• EN60950 (Europe)

• IEC 950 (National Deviations)

Emission Regulatory Approvals

• FCC Part 15J Class A (US/Canada)

• VCCI Class 2 (Japan)

• AS/NZS 3548 (Australia/New Zealand)

• EN55022 (CISPR 22) Class B (Europe)

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