Cisco IGX 8400 Series Switches

Universal Frame Relay Module (UFM)


Data Sheet

Universal Frame
Relay Module (UFM)

The Universal Frame Relay Module (UFM) series is a set of high-density, high-performance Frame Relay modules for Cisco IGX 8410, IGX 8420, and IGX 8430 wide-area switches. The UFM delivers standards-compliant UNI/NNI interfaces with high port and connection density at a lower per-port cost for both enterprise customers and service providers. Cisco's implementation of Frame Relay on these modules goes beyond industry standards for congestion avoidance and control mechanisms inside the network. Combined with the ATM infrastructure and advanced traffic management capabilities, this functionality offers unmatched performance for Frame Relay traffic.

Key Features

Superior Performance and Scale

The UFM uses a 64-bit mips RISC processor with advanced software to support the following functions:

  • Frame Relay Forum (FRF), ITU-T, and ANSI standards-based UNIs/NNIs with flexible port densities

    • 4 or 8 T1/E1 ports per module (channelized or unchannelized)

    • 12 V.35 ports per module

    • 12 X.21 ports per module

    • 4 HSSI ports per module

  • Permanent virtual connections (PVCs)

  • Local Management Interface (LMI) per ITU-T Annex A, ANSI Annex D, Strata LMI

  • Cisco's Enhanced Local Management Interface (ELMI)

  • Frame Relay to ATM interworking: network interworking and service interworking

  • Standards-based policing

  • Per-virtual-circuit queuing

  • Large, dynamically assigned buffers (96,000 buffers) per module

  • Per-virtual-circuit-rate scheduling

  • Cisco's implementation of per-virtual-circuit-based Foresight® license technology (closed loop congestion avoidance)

  • 1000 virtual connections per module

  • Statistics collection

  • Standards-based alarm and fault management

  • Simple Network Management Protocol (SNMP) configuration and access

  • Redundancy with hot standby switchover

Frame Relay Services

The UFM enables interconnection of routers, Frame Relay access devices (FRADs), and other frame-based devices to wide-area switches using Frame Relay UNIs. The UFM provides standards-based Frame Relay interfaces on IGX 8400 series switches to connect to any vendor's equipment via a UNI or NNI interface.

High Performance

Cisco's Frame Relay implementation uses the following unique mechanisms to deliver a high-performance solution.

Dual Leaky Bucket Policing (Frame-based GCRA)

Traffic entering the network is policed, according to a standards-based dual leaky bucket algorithm using Bc and Be as the bucket sizes. This setup ensures that traffic is accepted into the network, according to the service contract. Any traffic exceeding its contract is tagged as eligible for discard (DE bit is set).

Per-Virtual-Circuit Queuing at Ingress Frame Relay Ports

At the ingress, each virtual connection is provided with its own queue. This setup allows the network to accommodate bursts of data when traffic is allowed into the network and enables the firewalling of user traffic.

Large Buffering and Dynamic Buffer Management

Each UFM is equipped with 32,000 120-byte buffers for ingress traffic and 64,000 60-byte buffers for egress traffic. These buffers are dynamically allocated to each VC, depending upon the traffic entering the card. A patented mechanism optimizes the VCs performance and the efficiency of available resources.

Per-Virtual-Circuit-Rate Scheduling for Each VC

Each VC is serviced, at a minimum, to meet the service contract for that particular connection.

Congestion Avoidance and Control Mechanism (`ABR' for Frame Relay)

Cisco switches implement a per-VC rate-based closed loop congestion avoidance mechanism that, when combined with the per-virtual-circuit queues and the efficient rate control algorithm, yields extremely high trunk utilization, reducing overall networking costs and improving network performance.

Frame Relay to ATM Interworking

The UFM series of modules supports standards compliant Frame Relay to ATM Interworking. This includes both network interworking and service interworking (transparent and translation mode).

Traffic Management with Cisco Routers

The UFM series of modules implements a mechanism that enables an IGX 8400 network to inform a Cisco router of congestion on a per-VC basis in addition to standards-based FECN/BECN congestion notifications. This mechanism uses standards-based messages from the network to the user device over the UNI. These messages proactively inform the attached Cisco router of congestion in the network and allow the capability of the router to prioritize traffic at Layer-3 level using mechanisms in the router, for example weighted fair queuing (WFQ) and custom queuing.

Enhanced Local Management Interface

The UFM series of modules implements some enhanced information elements that operate across any standard-based LMI (Strata LMI, ANSI Annex D, ITU Annex A). These information elements facilitate a dynamic exchange of information between the wide-area switch and the router. UFMs are used by the switch to convey the traffic shaping parameters for a connection to the attached router. The router uses this information and autoconfigures these parameters to shape Frame Relay traffic on that virtual circuit.

Frame Forwarding

The UFM series of modules supports the Frame Forwarding mode, which enables the transport of frame-based traffic such as HDLC/SDLC/PPP. This mode enables point-to-point connections for frames that begin with a valid Flag (7E) and end with a two-byte in an integral number of octets.

Technical Specifications


  • 64-bit mips RISC processor

  • 512 KB of flash memory

  • 4 MB of RAM

  • 96,000 frames of buffering, dynamically allocated

  • MC68360 processor for administrative functions

Physical Layer

Description T1 E1
Line Rate

1.544 Mbps

2.048 Mbps


± 32 ppm

± 50 ppm

Connector Type




120 ohms

120 ohms balanced, 75 ohms balanced or unbalanced

Cable Length

0-622 ft

0-1,000 ft (-6 dB) at 1,024 kHz

Line Coding



Frame Format


Multiframe, clear channel

Minimum Pulse Density

Zero code suppression (LSB, MSB or B8ZS)

Zero code suppression (HDB3)


ANSI T1.102, T1.231, T1.403, ITU-T G.824

ITU-T G.703, G.704, G.706, G.732, G.735-9, G.775, G.823, G.826, I.431

Description V.35/X.21 HSSI
Line Rate

56 kbps-10.24 Mbps

1.024-16.384 Mbps

Clock Rate

n(1 to 32)*64K,

n(2 to 10)*1.024M

1.024 + n x 0.512M

Connector Type


50-pin SCSI

Interface Type



Physical/Electrical Specifications

Front card 15.25 x 16.25 in.; Back card 6.5 x 16.25 in.


Front card 8 lb (3.6 kg); back card 4 lb (1.8 kg)

Input Power

-48V DC

Power Consumption
  • UFM-U: 66W

  • UFM-C (V.35/X.21): 60W

  • UFM-C (HSSI): 87W

Electrical and Safety Standards
  • FCC Part 15

  • Bellcore GR1089-CORE

  • IEC 801-2, 801-3, 801-4, 801-5, 825-1 (Class 1)

  • EN 55022, 60950

  • UL 1950

Frame Relay

Frame Relay Interface
  • T1: 1-24 per line (up to 192 FR UNI/NNI interfaces/module)

  • E1: 1-31 per line (up to 248 FR UNI/NNI interfaces/module)

Interface Rates
  • T1: 56 kbps or n x 64 kbps, where 1<=n<=24. Sum of all n<=24

  • E1: 56 kbps or n x 64 kbps, where 1<=n<=31. Sum of all n<=31

  • (CAS, CCS or unframed)

Virtual Circuits

1000 per module

Performance Counters and Stats Per Port

18 stats per port

VC Statistics

19 stats per VC


24-Mbps configurable throughput, 16-Mbps sustained throughput

Frame to ATM Interworking
  • Network Interworking (FRF.5)

  • Service Interworking (FRF.8)

Configuration Flexibility
  • Up to 27 different configuration modes for V.35 and X.21

  • Up to 3 different configuration modes for HSSI

  • ITU-T I.233, I.365.1, I.370, I.371, I.372, I.555, Q.922A, Q.933A

  • ANSI T1.606, T1.617, T1.618, T1.634

  • FRF 1.1, FRF 2.1, FRF 3.1, FRF.5, FRF.6, FRF.8, FRF.9