RAD MiTOP-E1/T1 SFP-Format TDM Pseudowire Gateway
Key points of MiTOP-E1/T1- TDM circuit emulation over a packet-switched network (PSN) with CESoPSN (RFC 5086)
and SAToP (RFC 4553) payload encapsulation
• SFP enclosure
• ASIC-based architecture for minimizing processing delay
• Advanced clock distribution mechanism, and configurable jitter buffer
• Comprehensive OAM and performance monitoring
The RAD TMiTOP-E1/T1 is a TDM pseudowire (PW) access gateway extending TDM-based services over packet-switched networks. Housed in a Small Form-Factor Pluggable (SFP) enclosure, it is designed for quick and simple insertion into any 100BaseFx Ethernet device port with an MSA-compatible socket.
RAD MiTOP-E1/T1 is simple and cost-effective alternative to external, standalone gateways or conversion cards for each user device, saving on space, power consumption, cabling, and simplifying management.
The RAD MiTOP-E1/T1 gateway provide a legacy over PSN solution for transmitting E1/T1 streams over packet switched networks. The device converts the data stream from its user E1 / T1 ports into packets for transmission over the network. The addressing scheme of these packets is UDP/IP, MPLS or MEF. These packets are transmitted via a 100BaseFx port of the host device to the PSN. A remote pseudowire gateway converts the packets back to TDM traffic. High-performance ASIC-based buffering and forwarding techniques are used to achieve minimal end-to-end processing delay.
Configurable packet size allows to achieve proper balance between PSN throughput
and delay. Large configurable jitter buffer per each
PW connection compensates for the delay variation introduced by the PSN. The gateway supports the following encapsulation methods:
• Payload – CESoPSN and SAToP
• Network – MPLS, MEF, UDP/IP.
SFP ENCLOSURE of the RAD
Housed in a Small Form Factor Pluggable ( SFP ) package, RAD
MiTOP-E1/T1 complies with the Multi-Source Agreement.
Running on power derived from the host device, it requires no additional power supply.
RAD MiTOP-E1/T1 is hot-swappable and features a special release mechanism for easy extraction from the SFP socket.
For Ethernet networks – the outgoing
pseudowire packets are assigned a
dedicated VLAN ID according to 802.1Q
and marked for priority using 802.1p bits.
For IP networks – the outgoing pseudowire packets are marked for priority using ToS (including the DSCP and Diffserv bits). For MPLS networks – the outgoing pseudowire packets are assigned to a specific MPLS tunnel and marked for priority using EXP bits.
Synchronization between TDM devices is maintained, by deploying advanced clock distribution mechanisms. The clocking
• Internal – the master clock source for the TDM circuit is provided by the internal clock oscillator
• Loopback – the transmit clock is derived from the E1 / T1 port’s receive clock
• Adaptive – the clock is recovered from the PSN.
Advanced clock recovery conforms to G.823 using G.8261-defined scenarios. Jitter and wander of the recovered clock are maintained at levels that conform to G.823/G.824 traffic. For adaptive clock recovery, the recovered clock performance depends on packet network characteristics.
TDM INTERFACE of RAD MiTOP-E1/T1
The TDM port provides connectivity to any standard E1 or T1 device. E1 and T1 interfaces support:
• G.703, G.704, framed and unframed modes
• SF and ESF framing (T1).
MiTOP-E1/T1 is transparent to all signaling protocols.
RAD MiTOP-E1/T1 FAULT PROPAGATION
E1 or T1 loss of signal is propagated by sending an electrical LOS signal to the
100BaseFx port, and is visually indicated by the LOS LED (red) turning on. This in
turn can automatically turn off the LAN link. Turning on/off the packet link is user-configurable (enabled or
The MiTOPS can be managed using different ports and applications:
• Out-of-band via I2C channel (of the SFP edge connector)
• Inband via the Ethernet port, using a Web browser.
Management traffic can run over a dedicated VLAN.
OAM AND PERFORMANCE MONITORING RAD’s TDM PW OAM mechanism verifies connectivity and prevents pseudowire configuration mismatch. The following RFC-2495 E1/T1 physical layer performance statistics are available:
BES, ES, SES and UAS.
DIAGNOSTICS USING THE RAD MiTOP-E1/T1
External and internal loopbacks can be used to check TDM link connectivity. Alarms detected during operation are
stored in a buffer holding up to 100 events.
An optional configuration adapter is available for connecting MiTOP-E1/T1 to a PC via a USB 2.0 port. The configuration adapter is used for the preliminary configuration of the gateways or software download to the units.