Interfaces Terms
To understand interfaces, become familiar with the terms defined in Table 4.
Table 4: Network Interfaces Terms
Term | Definition |
|---|---|
alternate mark inversion (AMI) | Original method of formatting T1 and E1 data streams. |
asymmetric digital subscriber line (ADSL) interface | Physical WAN interface for connecting a J Series device to a digital subscriber line access multiplexer (DSLAM). An ADSL interface allocates line bandwidth asymmetrically with downstream (provider-to-customer) data rates of up to 8 Mbps for ADSL, 12 Mbps for ADSL2, and 25 Mbps for ADSL2+, and upstream (customer-to-provider) rates of up to 800 Kbps for ADSL and 1 Mbps for ADSL2 and ADSL2+, depending on the implementation. |
ADSL2 interface | An ADSL interface that supports ITU-T Standards G.992.3 and G.992.4 and allocates downstream (provider-to-customer) data rates of up to 12 Mbps and upstream (customer-to-provider) rates of up to 1 Mbps. |
ADSL2+ interface | An ADSL interface that supports ITU-T Standard G.992.5 and allocates downstream (provider-to-customer) data rates of up to 25 Mbps and upstream (customer-to-provider) rates of up to 1 Mbps. |
Annex A | ITU-T Standard G.992.1 that defines how ADSL works over plain old telephone service (POTS) lines. |
Annex B | ITU-T Standard G.992.1 that defines how ADSL works over Integrated Services Digital Network (ISDN) lines. |
binary 8-zero substitution (B8ZS) | Improved method of formatting T1 and E1 data streams, in which a special code is substituted whenever 8 consecutive zeros are sent over the link. |
Challenge Handshake Authentication Protocol (CHAP) | Protocol that authenticates remote users. CHAP is a server-driven, three-step authentication method that depends on a shared secret password residing on both the server and the client. |
checksum | See frame checksum sequence. |
channel group | Combination of DS0 interfaces partitioned from a channelized interface into a single logical bundle. |
channel service unit (CSU) | Unit that connects a digital telephone line to a multiplexer or other signal service. |
channelized E1 | 2.048-Mbps interface that can be configured as a single clear-channel E1 interface or channelized into as many as 31 discrete DS0 interfaces, or up to 30 ISDN PRI B-channels and 1 D-channel. On J Series channelized T1/E1/ISDN PRI interfaces, time slots are numbered from 1 through 31, and time slot 1 is reserved for framing. When the interface is configured for ISDN PRI service, time slot 16 is reserved for the D-channel. |
channelized interface | Interface that is a subdivision of a larger interface, minimizing the number of Physical Interface Modules (PIMs) that an installation requires. On a channelized PIM, each port can be configured as a single clear channel or partitioned into multiple discrete T1, E1, and DS0 interfaces. |
channelized T1 | 1.544-Mbps interface that can be configured as a single clear-channel T1 interface or channelized into as many as 24 discrete DS0 interfaces, or up to 23 ISDN PRI B-channels and 1 D-channel. When the interface is configured for ISDN PRI service, time slot 24 is reserved for the D-channel. |
Cisco HDLC | Cisco High-level Data Link Control protocol. Proprietary Cisco encapsulation for transmitting LAN protocols over a WAN. HDLC specifies a data encapsulation method on synchronous serial links by means of frame characters and checksums. Cisco HDLC enables the transmission of multiple protocols. |
clock source | Source of the consistent, periodic signal used by a device to synchronize data communication and processing tasks. |
CSU compatibility mode | Subrate on an E3 or T3 interface that allows a J Series device to connect to a channel service unit (CSU) with proprietary multiplexing at the remote end of the line. Subrating an E3 or T3 interface reduces the maximum allowable peak rate by limiting the payload encapsulated by the High-level Data Link Control protocol (HDLC). |
data-link connection identifier (DLCI) | Identifier for a Frame Relay virtual connection, also called a logical interface. |
data service unit (DSU) | Unit that connects a data terminal equipment (DTE) device—in this case, a J Series Services Router or an SRX Series Services Gateway— to a digital telephone line. |
data terminal equipment (DTE) | RS-232 interface that a Juniper Networks device uses to exchange information with a serial device. |
DS1 | Digital signal 1, another name for a T1 interface. |
DS3 interface | Digital signal 3, another name for a T3 interface. |
data inversion | Transmission of all data bits in the data stream so that zeros are transmitted as ones and ones are transmitted as zeros. Data inversion is normally used only in alternate mark inversion (AMI) mode to guarantee ones density in the transmitted stream. |
E1 interface | Physical WAN interface for transmitting signals in European digital transmission (E1) format. The E1 signal format carries information at a rate of 2.048 Mbps and can carry 32 channels of 64 Kbps each. |
E3 interface | Physical WAN interface for transmitting 16 E1 circuits over copper wires using time-division multiplexing. E3 is widely used outside of North America and transfers traffic at the rate of 34.368 Mbps. |
encapsulation type | Type of protocol header in which data is wrapped for transmission. |
Fast Ethernet interface | Physical LAN interface for transmitting data at 100 Mbps. Fast Ethernet, also called 100Base-T, additionally supports standard 10Base-T Ethernet transmission. Fast Ethernet is available on both dual-port and 4-port PIMs for the J4350 and J6350 devices. |
FPC | Logical identifier for a Physical Interface Module (PIM) installed on a J Series device. The FPC number used in the JUNOS command-line interface (CLI) and displayed in command output represents the chassis slot in which a PIM is installed. |
fractional E1 | Interface that contains one or more of the 32 DS0 time slots that can be reserved from an E1 interface. (Time slot 0 is reserved.) |
fractional T1 | Interface that contains one or more of the 24 DS0 time slots that can be reserved from a T1 interface. (Time slot 0 is reserved.) |
frame check sequence (FCS) | Calculation that is added to a frame to control errors in High-level Data Link Control (HDLC), Frame Relay, and other data link layer protocols. |
Frame Relay | An efficient WAN protocol that does not require explicit acknowledgement of each frame of data. Frame Relay allows private networks to reduce costs by sharing facilities between the endpoint switches of a network managed by a Frame Relay service provider. Individual data link connection identifiers (DLCIs) are assigned to ensure that customers receive only their own traffic. |
Gigabit Ethernet interface | Physical LAN or WAN interface for transmitting data at 1000 Mbps. The four built-in ports on J4350 and J6350 devices are Gigabit Ethernet interfaces. Gigabit Ethernet is also available in a single-port copper or optical PIM for these devices. Gigabit Ethernet is also supported in SRX Series devices. |
High-Level Data Link Control (HDLC) | International Telecommunication Union (ITU) standard for a bit-oriented data link layer protocol on which most other bit-oriented protocols are based. |
hostname | Name assigned to the device during initial configuration. |
ITU-T G.991.2 | International Telecommunication Union standard describing a data transmission method for symmetric high-speed digital subscriber line (SHDSL) as a means for data transport in telecommunications access networks. The standard also describes the functionality required for interoperability of equipment from various manufacturers. |
ITU-T G.992.1 | International Telecommunication Union standard that requires the downstream (provider-to-customer) data transmission to consist of full-duplex low-speed bearer channels and simplex high-speed bearer channels. In the upstream (customer-to-provider) transmissions, only low-speed bearer channels are provided. |
ITU-T G.993.2 | International Telecommunication Union standard describing a data transmission method for VDSL2 transceivers. |
ITU-T G.994.1 | International Telecommunication Union standard describing the types of signals, messages, and procedures exchanged between digital subscriber line (DSL) equipment when the operational modes of equipment need to be automatically established and selected. |
ITU-T G.997.1 | International Telecommunication Union standard describing the physical layer management for asymmetric digital subscriber line (ADSL) transmission systems. The standard specifies the means of communication on a transport transmission channel defined in the physical layer recommendations. In addition, the standard describes the content and syntax of network elements for configuration, fault management, and performance management. |
logical interface | Virtual interface that you create on a physical interface to identify its connection. Creating multiple logical interfaces allows you to associate multiple virtual circuits, data line connections, or virtual LANs (VLANs) with a single interface device. |
maximum transmission unit (MTU) | Maximum or largest segment size that a network can transmit. |
Multilink Frame Relay (MLFR) | Protocol that allows multiple Frame Relay links to be aggregated by inverse multiplexing. |
Multilink Point-to-Point Protocol (MLPPP) | Protocol that allows you to bundle multiple Point-to-Point Protocol (PPP) links into a single logical unit. MLPPP improves bandwidth efficiency and fault tolerance and reduces latency. |
Password Authentication Protocol (PAP) | Authentication protocol that uses a simple 2-way handshake to establish identity. |
Physical Interface Module (PIM) | Network interface card that is fixed or can be interchangeably installed on a J Series device to provide the physical connections to a LAN or WAN, receiving incoming packets and transmitting outgoing packets. A PIM contains one of the following interfaces or sets of interfaces:
|
Point-to-Point Protocol (PPP) | Link-layer protocol that provides multiprotocol encapsulation. PPP is used for link-layer and network-layer configuration. |
Packet Transfer Mode (PTM) | Transport of packet-based services method based on the EFM IEEE802.3AH standard. |
serial interface | Physical LAN interface for transmitting data between computing devices. A J Series device has two types of serial interfaces:
|
symmetric high-speed digital subscriber line (G.SHDSL) | Physical WAN symmetric DSL interface capable of sending and receiving high-speed symmetrical data streams over a single pair of copper wires at rates between 192 Kbps and 2.31 Mbps. G.SHDSL incorporates features of other DSL technologies such as asymmetric DSL and transports T1, E1, ISDN, Asynchronous Transfer Mode (ATM), and IP signals. |
symmetric high-speed digital subscriber line (SHDSL) transceiver unit–remote (STU–R) | Equipment that provides symmetric high-speed digital subscriber line (SHDSL) connections to remote user terminals such as data terminals or telecommunications equipment. |
T1 interface | Physical WAN interface for transmitting digital signals in the T-carrier system used in the United States, Japan, and Canada. The T1 signal format carries 24 pulse code modulation (PCM) signals using time-division multiplexing (TDM) at an overall rate of 1.544 Mbps. |
T3 interface | Physical WAN interface for transmitting digital signals in the T-carrier system used in the United States, Japan, and Canada. T3 signals are formatted like T1 signals, but carry information at the higher rate of 44.736 Mbps. T3 is also called DS3. |
VDSL2 | VDSL2 is an enhancement to G.993.1 (VDSL) that permits the transmission of asymmetric and symmetric (full duplex) aggregate data at faster rate. VDSL2 is based on ITU-T G.993.2 (VDSL2) standard. |