# What are the differences between a channelized E1 interface and an unchannelized E1 interface of an AR router

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The differences between a channelized E1 interface and an unchannelized E1 interface of an AR router are described as follows:

- An unchannelized E1 interface works as an interface not divided by timeslots, whose bandwidth is 2.048 Mbit/s.
- For a channelized E1 interface, all the 31 timeslots can be randomly divided into multiple groups (channel sets). Each group is corresponding to a separated channel whose rate can be calculated as follows: n x 64 kbit/s, in which n ranges from 1 to 31.
- For a partially channelized E1 interface, the 31 timeslots can be randomly bundled into a channel whose rate can be calculated as follows: n x 64 kbit/s, in which n ranges from 1 to 31.

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Description of the E1 interface of an AR router
1. E1/T1: E1/T1 is a technology of using the synchronous time division multiplexing technology to combine multiple audio channels into a 2 Mbit/s or 1.5 Mbit/s high-speed channel. - Maximum rate of E1 cards: 32 (timeslots) x 64 (kbit/s per timeslot) = 2048 kbit/s - Maximum rate of T1 cards: 24 (timeslots) x 64 (kbit/s per timeslot) = 1536 kbit/s - CE1/CT1 cards can determine multiple groups of timeslots and have the Controller view. However, E1 cards can determine only one group of timeslots in the framed mode (other timeslots cannot be used). 2. E1 interfaces are configured on E1/T1 cards and can be seen as serial interfaces (currently supported by AR1200(S)/AR2200(S)/AR3200(S)/AR3600). - 1E1T1-M/2E1T1-M support the E1/CE1/CT1/PRI(E1&T1) interface. - 4E1T1-M/8E1T1-M support the E1/CE1/PRI(E1) interface. - 1E1T1-F/2E1T1-F support the framed/unframed E1/T1 interface. - 4E1T1-F/8E1T1-F support the framed/unframed E1 interface. - The character M in a model name indicates Multiflex Trunk, that is, the model can be fully channelized. The character F in a model name indicates Fractional, that is, the model can be partially channelized. 3. The CE1/PRI interface is the physical interface of the E1 system. It can work in E1 mode (unchannelized mode) or CE1/PRI mode (channelized mode). - In E1 mode, the CE1/PRI interface works as an interface not divided by timeslots, whose bandwidth is 2.048 Mbit/s. - In CE1/PRI mode, the 2M line is divided into 32 timeslots of 64 KB, which are numbered from 0 to 31. Timeslot 0 is used to transfer frame alignment information. a. CE1 interface: All timeslots except timeslot 0 are randomly divided into multiple groups (channel sets). Each group is corresponding to a separated channel. b. PRI interface: Bundle timeslot 16 (D channel) and any one of timeslots 1 to 15 or 17 to 31 (B channel) into a group (PRI set). c. CE1 interfaces can be divided into multiple groups. However, only one group can be bundled for PRI interfaces. 4. The CT1/PRI interface is the physical interface of the T1 system. - CT1 interface: All timeslots (timeslot 1 to 24) can be randomly divided into multiple groups. Timeslots in each group are bundled into a channel set. - PRI interface: Randomly bundle timeslot 24 (D channel) and any one of timeslots 1 to 23 (B channel) into a group (PRI set). - CT1 interfaces can be divided into multiple groups. However, only one group can be bundled for PRI interfaces. 5. E1 interfaces, channel sets, and PRI sets can all be seen as serial interfaces, which have the same logical characteristics as synchronous serial interfaces and support IP network protocols and protocols in the data link layer, such as PPP and HDLC frame relay X.25 protocol (PRI sets do not support the HDLC frame relay X.25 protocol and channel sets of CT1 interfaces do not support the X.25 protocol).

Do AR routers support E1 interfaces
E1 interfaces that AR routers support are described as follows: E1 interfaces are configured on E1/T1 cards and can be seen as serial interfaces (currently supported by AR1200/AR2200/AR3200/AR3600). - 1E1T1-M/2E1T1-M support the E1/CE1/CT1/PRI(E1&T1) interface. - 4E1T1-M/8E1T1-M support the E1/CE1/PRI(E1) interface. - 1E1T1-F/2E1T1-F support the framed/unframed E1/T1 interface. - 4E1T1-F/8E1T1-F support the framed/unframed E1 interface.

What are the differences between the E1 interface and the serial interface of an AR router
The differences and relationship between the E1 interface and the serial interface of an AR router are described as follows: The serial interface of an AR router uses the DB9 female connector. It is the physical implementation of the E1 interface and is used transmit data in lines with 2 Mbit/s and lower bandwidth. DB9 male connectors used on PCs are also called serial interfaces in some scenarios. However, these interfaces are used only to connect to the console interface of routers for device debugging.

The state of the E1 interface of an AR router is not Up
If the state of the E1 interface of an AR router is not Up, perform the following steps: 1. If the physical state of the interface is not Up, check the physical cables. - If coaxial cables are used for the communication between devices, exchange the sending cable and receiving cable. - If balanced cables are used for the communication between devices, check whether line order of the cables is correct. The line order of the DB9 connector on the card: Line 1 and line 2 are the receiving lines. Line 6 and line 7 are the transmitting lines. The line order of the RJ45 connector used by balanced cables: Line 1 and line 2 are the transmitting lines. Line 4 and line 5 are the receiving lines. 2. Check whether the configuration of the E1 interface is consistent with that of the interconnected physical interface. - Enter the Controller interface view and run the display this command to check the configuration of the Controller interface. - Check whether the physical attributes of the Controller interfaces on both ends are consistent, such as the frame format, coding format, data inversion, cable impedance, and timeslot number. - The clocks at both ends must work in master/slave mode. - If the configurations of the interfaces are not consistent, or the state of the interface alternates between Up and Down, configure the interfaces on both ends again. - If the configurations of the interfaces on both ends are consistent and meet the requirements above, and if the physical state of the interface keeps Up stably, perform step 3. 3. Check whether the configurations of the serial interfaces on both ends are consistent. - Enter the serial interface view and run the display this command to check the configuration of the serial interface. - Check whether the attributes of the serial interfaces on both ends are consistent, such as the encapsulation and CRC methods. If the PPP authentication method is used, check whether the authentication methods used by both ends are consistent, whether the user names and passwords are correct, and whether the FR-DLCI configurations are consistent. In addition, check whether the serial interfaces are shut down. - If the configurations of the serial interfaces on both ends are not consistent, configure the serial interfaces again. - If the interface cannot send and receive data properly even if the configurations of the serial interfaces on both ends are consistent, perform step 4. 4. Check whether the serial interfaces transmit and receive data. - Enter the views of the serial interfaces and run the display this interface command to check whether the serial interfaces on both interconnected ends transmit data. - If the serial interfaces do not transmit data, the negotiation packet in the upper layer is not sent properly. In this case, try to run the shutdown command or undo shutdown command to trigger the sending of the negotiation packet in the upper layer. - If the serial interfaces transmit and receive data, perform step 5. 5. Check whether the data transmitted or received by the serial ports includes error packets. - Enter the views of the serial interfaces and run the display this interface command to check whether the data received by the serial interfaces on both interconnected ends includes a large number of CRC error packets and whether the number of error packets increases. - If the data received by the serial interfaces includes a large number of CRC error packets, check whether the cables are connected firmly. For the problem that the state of an E1 interface of an AR router is not Up, see the troubleshooting guide. For details, access the URL in the right column.

Check the status of the E1 interface on the AR router
Check the status of the E1 interface on the AR router as follows: Run the display controller [ e1 [ interface-number ] ] command to check the information about the CE1/PRI interface, or run the display fe1 serial interface-number command to check the basic configuration and alarms of the E1-F interface. display controller e1 1/0/0 E1 1/0/0 current state : UP //Indicates that the state of the interface is Up. Description: HUAWEI, AR Series, E1 1/0/0 Interface Basic Configuration: //The following parameters must be consistent with those of the peer end (except for the clock) Work Mode is E1 Framed, Cable type is 120 Ohm balanced. //The work mode is E1, and the cable type is 120ohm twisted pair cable. Frame-format is NO-CRC4, Line Code is Hdb3. //The frame format is NO-CRC4, and the line code is Hdb3. Source Clock is Slave, Data-coding is Normal. //The clock status is slave, and the clock signal is not inverted. Idle code is 7E, Itf type is 7E, Itf number is 4. //The idle code and the type of characters filled between frames are 7e, and the number of characters filled between frames is 4. Loopback is Not Set. Alarm State: Receiver alarm state is Loss-of-Frame. Transmitter is sending remote alarm. Historical Statistics: //Perform error packet statistics. If the number of error packets increases, you can invert the clock. Data in current interval (0 seconds elapsed): 0 Line Code Violations, 0 Path Code Violations 0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins 0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs Total Data (last 24 hours): 0 Line Code Violations, 0 Path Code Violations 0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins 0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

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