ATM Network Termination Unit

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Metrodata ATM Network Termination Units are a 2-port ATM switch which performs interface conversion and ATM service demarcation functions.

ATM Network Termination Units

ATM Network Termination Unit Application Diagram

  • STM1 UNI media conversion and ATM service demarcation
  • Wide variety of European & North American interface standards supported
  • User friendly set-up menus - easy to install & configure
  • Comprehensive performance monitoring & diagnostics
  • Integral remote management supporting Telnet & SNMP
  • All units 19 inch rack-mountable, 1U high
  • Optional universal AC or -48VDC power supply

Product Variants

ATM Network Termination Unit Application Diagram

The Metrodata ATM Network Termination Unit (NTU) provides a media conversion and ATM service demarcation function for STM-1/OC-3 ATM services. A wide variety of copper and fibre interface types are supported which mean that these services can be installed with whatever is the most suitable cabling, and offer the exact interface required by the user thereby minimising installation costs.

The ATM NTU has two different ATM interfaces. Cell traffic received at these interfaces is analysed for errors, idle cells are deleted and valid traffic is then forwarded to the ATM cell buffer. When bandwidth is available traffic is extracted from the ATM cell buffer and transmitted out of the other interface. If the ATM cell buffer becomes full, then cells are discarded until space becomes available. If there is no traffic queued, the DSU transmits idle cells in lieu of traffic.

The ATM NTU has built in diagnostic loops which segment the link and assist in locating device, cabling or network faults. Extensive performance monitoring statistics are also gathered and stored for 24 hours. This provides a substantial database for assessing the performance of the network, which can be used to identify alarms, errors or data loss. Front panel LEDs also give indication of major and minor alarms.

The default configuration is sufficient to get most installations applications operational, making this a truly plug and play device. Configuration can be performed via a menu driven console port, or via an integrated LM1100 SNMP enabler port which offers substantial Telnet and SNMP capability.

The electrical interfaces supported are as follows:

  • G.703 BNC offering transmission over coaxial cable
  • RJ45 offering transmission over twisted pair cable

The main fibre interfaces supported are as follows:

  • 1300nm multimode offering transmission distances up to 5km over multimode fibre
  • 1300nm singlemode short haul offering transmission distances up to 30km over singlemode fibre
  • 1300nm singlemode long haul offering transmission distances up to 70km over singlemode fibre

Using fibre optics these products extend the operating distance for an STM-1/OC-3 interface to 5km using low cost multimode fibre, or to either 30km or 70km using singlemode fibre. Despite these quoted maximum operating distances, specific installations may only operate over lower distances due to the variations in losses of different types of fibre cable, the use of connecting fibre cables, or patch panels. When operating over 50% of the maximum distances it is advisable to calculate all fibre optic connector and cable losses and compare these with the fibre optic loss budget specified for this product.

As standard fibre ports are supplied with SC connectors and operate at a nominal wavelength of 1300nm. Other wavelengths are available on request, e.g. 850nm, 1550nm, 1550/1300 WDM. Other connector options are also available on request, e.g. ST, FC.

Singlemode Short Haul Interface
Port G.957
Interface Dual SC Singlemode 8/125um
Wavelength 1310um
Tx Power -8 dBm to -15 dBm
Max Rx input power -8 dBm
Rx Sensitivity -8 to -31 dBm
Optical Loss Budget -15-(-31) = 16dB
Singlemode Long Haul Interface
Port G.957
Interface Dual SC Singlemode 8/125um
Wavelength 1310um
Tx Power 0 dBm to -5 dBm
Max Rx input power -8 dBm (may need attenuator
Rx Sensitivity -8 to -34 dBm
Optical Loss Budget -5-(-34) = 29dB
Multimode Fibre Interface
Port G.957
Interface Dual SC Multimode 62.5/125um
Wavelength 1310um
Tx Power -14 dBm to -19 dBm
Max Rx input power -14 dBm
Rx Sensitivity -14 to -30 dBm
Optical Loss Budget -19-(-30) = 11dB
SDH/Sonet BNC Electrical Interface
Physical BNC (75 ohm) balanced
Cable 75 ohm coax
Encoding CMI
Cable Lengths RG59 = 70m, UR202 = 80m
SDH/Sonet RJ45 Electrical Interface
Physical RJ45 (120 ohm) unbalanced
Cable 75 ohm STP
Encoding NRZ
Cable Lengths RG59 = 70m, UR202 = 80m
SDH/Sonet ATM Interface Higher Layers
Rate 155.52Mbps per G.957
Cable Sonet/STS-3c SDH/STM-1 per G.709
Encoding I.432
Clocks Internal, Loop, Though
Environment
Temp 0-50 deg
Humidity 0-95% RH, non condensing
Pressure 86-106 kPa

Power Supply
AC Mains 100-250 VAC, 50-400Hz, 250mA, IEC connector
DC Power -36 to -72 VDC, 200-100mA

Packaging
Type 1U, 19 inch rack mount
Dimensions 425 x 213 x 44 (W x D x H)

Compliance
Safety EN60950
EMC EN55022, EN50082
Management RFC1213 (MIBII), RFC1495 (Telnet), RFC1157 (SNMP), RFC1406 (DS1/E1),
RFC1407 (DS3/E3), RFC1595 (Sonet), RFC1215 (Traps)
Statistics G.821, AT&T54016:15min, 24hr totals

Status & Diagnostics
Loop backs Local per port per direction
L0/1 Stats Transmission faults
L2 Stats Cell throughput, good cells, bad cells, corrected cells

Alarms
Line Major, minor
UNI ATM UNI fault
Part Number
Electrical User Equipment Interfaces 100-250 AC Mains -48 DC Power
RJ45 - BNC STM-1 80-10-110 80-22-110
RJ45 - SM SC SH STM-1 80-10-108 80-22-108
RJ45 - SM SC LH STM-1 80-10-109 80-22-109

Part Number
Fibre User Equipment Interfaces 100-250 AC Mains -48 DC Power
MM SC - BNC STM-1 80-10-098 80-22-098
MM SC - SM SC SH STM-1 80-10-080 80-22-080
MM SC - SM - SC LH STM-1 80-10-089 80-22-089

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