What does an IP Tube do?

The IP•Tube T1/E1 transparently maintains the proprietary signaling required to support T1 or E1 voice and data communications over IP and Ethernet networks. 

What configurations are available?

The IP•Tube T1/E1 is available with one to four T1/E1 interfaces and with one to two 10/100 BaseT Ethernet interface(s). The T1 interfaces have configurations that provide independent protocol, compression, packet sizing, buffering, clocking, framing, coding and channel settings. 

How does IP•Tube T1 Encapsulate T1 and Serial voice and data into IP?

The IP•Tube T1/E1 models encapsulate full and fractional T1 or E1 TDM circuits, along with their framing and signaling bits, into IP packets. The IP•Tube QT1 models encapsulate from one to four full and fractional T1 or E1 and TDM circuits, along with their framing and signaling bits, into IP packets. The IP•Tube's TDM Over IP connection provides for the transparent interconnection of PBXs, Telecom Switches and T1/E1 based communication systems via LANs, WANs, MANs, and Wireless Ethernet interconnects. 


How does IP•Tube T1 Lossless Data Compression Work?

The IP•Tube T1/E1•C adds the power of lossless data compression. The lossless data compression option is ideal for environments where network bandwidth is limited such as point-to-point and point-to-multipoint wireless, HFC cable modems, xDSL, Power Line Ethernet or the Internet. This optional functionality continuously detects idle/redundant data within each DS0 resulting in as much as a 56 to 1 bandwidth savings. TDM over IP bandwidth is not consumed by silent or redundant circuits. The IP•Tube T1/E1•C employs a compression method that significantly reduces redundant data sent across the IP network. At a high level, this means that when the data is repeating, such as when a line is idle, the sending IP•Tube send the minimal information for the receiving IP•Tube to reconstruct the data.

The compression ratio is based upon the frames per packet setting of the IP•Tube’s T1/E1 interface. The IP•Tube protocol encapsulates from 8 to 40 T1/E1 frames in an IP packet. If all the bytes in a DS0 channel for all the frames in a packet are identical, the sending IP•Tube only sends the single identical byte rather than all of the identical bytes for each frame in the packet. To extend this further, if it turns out the entire T1 circuit is idle or containing redundant data, the IP•Tube ends up only sending the equivalent of a single frame of data, rather than 8 or 40 frames per IP packet. Therefore the IP bandwidth is reduced, depending on the amount of redundant data on the T1 line at any given time. 

Does IP•Tube T1 support Quality of Service to prioritize packets?

The IP•Tube T1/E1 uses the Type of Service byte in the IP packets to prioritize the encapsulated T1/E1 frames. The setting of the TOS byte can be used to ensure that the real time TDM data from the IP•Tube is ensured high priority. Intermediary routers and switches can be configured for Quality of Service (QoS) prioritization to ensure that IP•Tube packets receive highest priority as they are routed through the IP interconnect. Quality of Service functionality is required within each router or switch that is within the interconnect between the IP•Tubes. QoS could be configured based on the IP•Tube Ethernet IP addresses, but a more straightforward method makes use of the unique UDP port number used by the IP•Tube. Engage has registered UDP port assignment 3175 (reference www.iana.org/assignments/port-numbers). QoS

configuration to prioritize UDP packets destined for port 3175 can be setup. Communication between IP•Tube systems uses packets destined for a configurable UDP port number. The IP•Tube defaults to UDP port 3175. 

What is the latency overhead for the IP•Tube?

The IP•Tube T1/E1 encapsulation of T1/E1 data into IP/UDP packets for transmission over Ethernet adds overhead due to the Ethernet, IP, and UDP headers – a total of 44 bytes. This 44 byte overhead should be taken into account when considering Ethernet bandwidth utilization.



• A DS0 is a 64 Kbps Voice/Data circuit.
• A Full T1 circuit is configured for 24 DS0s. The T1 signal is divided into frames, with one byte (8 bits) allocated for each configured DS0 and 1 framing bit for a total of 193 bits per frame = (24 * 8) + 1.
• A Full E1 circuit is configured for 31 DS0s. The E1 signal is divided into frames, with one byte (8 bits) allocated for each configured DS0 and 1 framing/signaling byte (8 bits) for a total of 32 bytes or 256 bits per frame. The Tube Frames-per-Packet (FPP) setting controls the number of T1 data frames to be encapsulated in a single IP/UDP packet. Increasing FPP reduces the effect of this 44 byte overhead. The encapsulation overhead can be expressed as a ratio of (Data + Overhead)/ (Data) and can be used to calculate the Ethernet bandwidth utilization for a given T1 configuration.