Purpose of TDM over Packet technology

Telecom companies and enterprise users can save network and equipment costs and generate additional revenue by offering different types of services over a single packet-switched infrastructure by the use of T1oP equipment. The T1oP equipment is also suitable for connecting to Ethernet/packet wireless equipment to achieve fast deployment of T1 services over wireless Ethernet networks. One particular application is to build T1 links with low-cost wireless LAN bridges, replacing expensive TDM/T1 microwave radios. The 2 x T1 over Ethernet (VCL-T1oP) multiplexer may be used to provide legacy TDM services over Gigabit Ethernet optical fiber or wireless Ethernet/IP networks.

How does the TDM over Packet (2 T1 Port GE Version) equipment work?

The T1 data streams received on the T1 interfaces are converted by the T1oP engine of the T1oP equipment to Ethernet data packets (of a fixed size) and transported over the Ethernet network with UDP/IP, MEF, or MPLS headers. At the receiving end, the T1oP reconstructs the original data streams by removing the IP, MEF, or MPLS headers and converts the Ethernet data packets back to T1 frames using a highly reliable and accurate clock recovery mechanism. The 'VCL-T1oP' (2 T1 Port GE Version) offers the user a choice of standard T1-to-packet and packet-to-T1 conversion mechanisms that include SAToP and CESoPSN technologies.

T1 and T1oP Interface

• Supports 2 independent T1 interfaces.
• Circuit emulation platform that migrates existing TDM-based legacy services to a next-generation network.
• Supported standard TDM over IP RFCs:
• RFC 5086 - Structure-Aware Time Division Multiplexed (TDM) Circuit Emulation Service over Packet Switched Network (CESoPSN) (12/2007)
• RFC 5087 - Time Division Multiplexing over IP (TDMoIP) (12/2007)
• RFC 4553 - Structure-Agnostic Time Division Multiplexing (TDM) over Packet (SAToP) (06/2006)
• Clock options: Internal, External, Adaptive, Recovered Clock, and Asymmetrical (One-Clock and Two-Clock) options for the T1 TDM port synchronization. Automatic clock priority selection with fallback.
• Supports CESoPSN payload mechanism to support the fractional T1 with data rate of 64Kbps to 1.544 Mbps (DS0 timeslot level). User-configurable data rate from 64 kbps to 1544 kbps, in steps of 64 kbps.
• The CESoPSN payload mechanism feature allows the user to optimize the packet-switched network by limiting its usage to the corresponding number of timeslots carried by a T1 channel.
• Supports SAToP payload mechanism to transport full T1 (transparent to the structure of the TDM frame, useful for transporting framed/unframed T1 channels).
• Supports IETF-PWE3 (pseudo-wire), SAToP, and CESoPSN transport mechanisms.
• Supports IP, MPLS, and MEF8 (Metro Ethernet) tagging.
• Supports two line codes—AMI and B8ZS.
• Supports three T1 framing modes—framed ESF, framed SF, and unframed.
• Supports point-to-point, point-to-multipoint, and drop-and-insert applications.
• Supports network latency/packet delay variation/jitter buffer of up to 512 ms.
• Absolute and differential time stamps.
• Jitter and Wander conforms to G.823 / G.824 and G.8261 and TDM specifications.
• RJ45—100 ohms balanced T1 interfaces.
• T1 Local and Remote Loop-back (RLOOP) facility for testing and diagnostics.

Ethernet/IP Network Interface

• Switching capacity up to 6 Gbps, non-blocking.
• 4 GigE Ports.
• Optical SFP-based (1000Base-FX) and electrical (10/100/1000Base-T) Ethernet port options.
• 2 x 10/100/1000BaseT Copper Ports
• 2 x 1000BaseFX Optical Fiber Ports.
• Point-to-point and point-to-multipoint applications based on IP addressing.
• Supports drop and insert applications.
• Port Control Ingress Rate Limiting.
• 1+1 Ethernet link redundancy
• Rapid Spanning Tree Protocol
• Ethernet Port Trunking.
• User-configurable MTU (T1oP payload) packet size up to 1800 bytes.
• Configurable payload size for each bundle.
• The switch supports jumbo frame sizes of up to 9000 bytes.
• Supports 802.1Q-based QoS and 802.1p-based packet priority.
• Port-based Priority (Classifying Services).
• DSCP and 802.1Q/802.1p-based packet tagging and prioritization.
• Flow Control in an Ethernet Packet Networks (Regulating Traffic).
• Port/customer-based bandwidth allocation (port rate limiting).
• MPLS, MEF, and UDP tagging for Ethernet traffic.
• Separate IP address for TDM traffic and equipment management.
• VLAN tagging for TDM traffic and equipment access/management.
• Single/double 802.1Q VLAN tagging (Q in Q VLAN Tagging)—user-configurable.
• UDP-specific “special” Ethernet type.
• In band VCCV ARP.
• Broadcast DA.

Few Key Features Explained

• Port-Based Priority (Classifying Services)—The port-based Priority feature allows the user to assign priority to the individual Ethernet ports so that traffic can be regulated according to the port on which that service is connected. The user may also assign highest priority to TDM (T1/DS3/T3) traffic and Ethernet services on a lower priority.
• VLAN-based Priority (Classifying Services)—The VLAN-based priority feature allows the user to assign priorities to different VLANs carrying various types of services/traffic according based on user categories and preferences. The user may assign the highest priority to TDM (T1/DS3/T3) traffic and Ethernet services on a lower priority. Users may also configure which TDM link should be given preference over the other TDM links when the uplink bandwidth falls below a particular threshold.
• Flow Control in an Ethernet Packet Networks (Regulating Traffic)—The flow control feature allows the user to regulate Ethernet traffic flow to minimize packet loss due to data bursts.
• Port/customer-based bandwidth allocation (port rate limiting)—Port-based ingress Ethernet rate limiting allows the user to assign the bandwidth as per port/service requirements, in addition to provisioning traffic by using 802.1Q and 802.1p VLANs and packet priority.