3Com 10014299 manual 3Com Router

10CHAPTER 1: 3COM ROUTER INTRODUCTION

New Features of the New features have been added to the 3Com Router1.10.

3Com Router 1.x

Support New Interfaces E3 and CE3 Interfaces

Both E3 and E1 are part of the ITU-T digital carrier architecture and are used in most regions beyond North America. The data transmission speed of E3 is

34.368 Mbps and the line code is HDB3. E3/CE3 interfaces support the link layer protocols including PPP, HDLC, Frame Relay, LAPB, and X.25, as well as the network protocol such as IP. Similar to E1/CE1, E3/CE3 interfaces can work in two operating modes, namely, E3 mode and CE3 mode.

■When working in E3 mode, an E3/CE3 interface is a timeslot-less interface of the bandwidth of 34.368 Mbps.

■When working in CE3 mode, it can multiplex/demultiplex 16 channels of E1 signals. The E3-to-E1 multiplexing is compliant with the G.751 and G.742 provisions of ITU-T. In addition, each E1 interface can be divided into 32 timeslots.

E1-F/T1-F Interface

E1-F and T1-F interfaces refer to the fractional E1 and T1 interfaces, which are equivalent to the simplified CE1/PRI and CT1/PRI interfaces. In essence, they are a low-cost approach to E1/T1 access. In a simple E1 or T1 access application requiring neither division of multiple channel groups nor ISDN PRI, either the E1-F or T1/F interface will be a good choice.

Null Interface

The functions of the Null interface are similar to those of null devices supported by many operating systems. It is always in UP status, but cannot forward data packets or configure IP addresses or encapsulate other protocols. Null interface is a virtual interface with software characteristics. Any network data packet sent to this interface will be dropped.

FRoIP and FRoISDN Frame Relay over IP

As IP networks have gained wider acceptance, Frame Relay (FR) applications have relied on IP networks for data communication and interconnection between networks. FRoIP technology enables IP networks to carry FR data by establishing a GRE tunnel across the IP network to connect the two FR networks at both ends of the IP network.

Frame Relay over ISDN

Frame Relay over ISDN provides a method for accessing the Frame Relay network based on ISDNs and the related devices. This shortens the time for users to access and lowers the cost of leased lines.

The Frame Relay over ISDN is mainly used in the following two aspects:

■The simplest application is to take Frame Relay over ISDN as the main communications method. That is, all the routers support Frame Relay over ISDN, and the individual routers can directly access the Frame Relay networks (without TA adapters) to communicate.