IP over E1 (IPoE1) is a technology that transmits Internet Protocol (IP) packets over E1, T1, E3, T3, or Synchronous Digital Hierarchy (SDH) links on the existing time division multiplexing (TDM) network. It provides IP packet transmission channels by binding multiple timeslots or E1 links, and uses Compressed Real-time Transport Protocol (cRTP) and IP Voice Compressor Plus (iVCP, a Huawei proprietary solution for IP voice data compression) to further improve bandwidth utilization.This feature requires the cooperation of the media gateway (MGW, UMG8900) and media gateway controller (MGC) to work .

Benefits of deploying IP service over TDM E1:

• Voice over IP (VoIP) services provided over the existing TDM network; reduced operation cost. No need to deploy new IP links with this.
  
• Improved voice bandwidth utilization with cRTP and iVCP, these are Huawei proprietery function on UMG.

Note limitations exists in IP E1 solution such as shown below;

• In IP over E1, serial and virtual-template (VT) interfaces support cRTP and iVCP. If cRTP or iVCP is enabled on the local UMG8900, the peer device (a BSC, UMG8900, or router) must use the same compression technology.

• When an E1 link fails, the UMG8900 automatically reduces the bearer bandwidth but does not report the E1 failure to the MGC. Therefore, the UMG8900 does not adjust the number of virtual Termination IDs (TIDs) according to the E1 link status. However, because the available bearer bandwidth is reduced, the number of available virtual TIDs is also reduced.

• If the transmission path contains satellite links, the minimum interval for keep-alive packets can only be 500 ms.

• If the UMG8900 is connected to a router over E1, user and transmission channel binding must be disabled.

• IP over E1 is suitable for small or medium-sized networks. It is used typically when carriers do not want to build a new IP bearer network or only want to provide IP bearer services at a few sites. It is advised, however, not to use IP over E1 in large networks.

Implementation Scenarios:

Scenario 1

The UMG8900 and the base station controller (BSC) are located in the same equipment room far away from the MGC. The UMG8900 connects to the BSC through FE/GE interfaces (directly or over a Layer-3 switch), and to the MGC through IPoE1 interfaces over a router. The router converts between IPoE1 and FE interfaces.

Scenario 2

The UMG8900 and the MGC are located in the same equipment room. The BSC is located far away. The UMG8900 connects to the MGC through FE/GE interfaces, and to the BSC through IPoE1 interfaces.

Scenario 3

The UMG8900, BSC, and MGC are all located in different equipment rooms. The UMG8900 connects to the BSC through IPoE1 interfaces, and to the MGC through IPoE1 interfaces over a router, which converts between IPoE1 and FE interfaces.

Scenario 4

The UMG8900s are connected in the following ways:

• The UMG8900s that are controlled by the same MGC are directly connected through IPoE1 interfaces.
• The UMG8900s that are controlled by different MGCs are connected through IPoE1 interfaces over an SDH transmission network.

Scenario 5

The UMG8900 and the BSC are located in the same equipment room far away from the MGC. The UMG8900 connects to the BSC directly through TDM interfaces, and to the MGC through IPoE1 interfaces over a router, which converts between IPoE1 and FE interfaces.

In this scenario, the signaling messages and bearer data on the BSCs A interface are transmitted to the UMG8900 over TDM links. The narrowband signaling messages are converted into broadband signaling messages on the UMG8900 and then sent to the MGC over the SIGTRAN interface, and the bearer data is packetized on the UMG8900 and then sent to other network elements (NEs) over IP bearer interfaces.

useful document, thanks