Special Interfaces

dsc

Discard interface. See Discard Interface.

fxp0

In a J-series Services Router chassis cluster configuration, configurable management interfaces are created from built-in interfaces on the connected J-series chassis. The fxp0 interface is the management port, and fxp1 is used as the control link interface in a chassis cluster.

In an SRX-series services gateway, the fxp0 management interface is a dedicated port located on the Routing Engine. In an SRX-series services gateway chassis cluster configuration, the control link interface must be port 0 on an SPC. For each node in the chassis cluster, you must configure the SPC that is used for the control link interface.

For more information about chassis clusters, see the JUNOS Software Security Configuration Guide.

For more information about the device management port interfaces, see Management Interface.

gr-0/0/0

Configurable generic routing encapsulation (GRE) interface. GRE allows the encapsulation of one routing protocol over another routing protocol.

Within a J-series device, packets are routed to this internal interface, where they are first encapsulated with a GRE packet and then re-encapsulated with another protocol packet to complete the GRE. The GRE interface is an internal interface only and is not associated with a physical medium or PIM. You must configure the interface for it to perform GRE.

gre

Internally generated GRE interface. This interface is generated by the JUNOS software to handle GRE. It is not a configurable interface.

ip-0/0/0

Configurable IP-over-IP encapsulation (also called IP tunneling) interface. IP tunneling allows the encapsulation of one IP packet over another IP packet.

Generally, IP routing allows packets to be routed directly to a particular address. However, in some instances you might need to route an IP packet to one address and then encapsulate it for forwarding to a different address. In a mobile environment in which the location of the end device changes, a different IP address might be used as the end device migrates between networks.

Within a J-series device, packets are routed to this internal interface where they are encapsulated with an IP packet and then forwarded to the encapsulating packet's destination address. The IP-IP interface is an internal interface only and is not associated with a physical medium or PIM. You must configure the interface for it to perform IP tunneling.

ipip

Internally generated IP-over-IP interface. This interface is generated by the JUNOS software to handle IP-over-IP encapsulation. It is not a configurable interface.

lo0

Loopback address. The loopback address has several uses, depending on the particular JUNOS feature being configured. See Loopback Interface.

lo0.16384

Internal loopback address. The internal loopback address is a particular instance of the loopback address with the logical unit number 16384. It is created by the JUNOS software as the loopback interface for the internal routing instance. This interface prevents any filter on lo0.0 from disrupting internal traffic.

ls-0/0/0

Configurable link services interface. Link services include the multilink services MLPPP, MLFR, and Compressed Real-Time Transport Protocol (CRTP).

Within a J-series device, packets are routed to this internal interface for link bundling or compression. The link services interface is an internal interface only and is not associated with a physical medium or PIM. You must configure the interface for it to perform multilink services.

For more information about multilink services, see Services Interfaces.

lsi

Internally generated link services interface. This interface is generated by the JUNOS software to handle multilink services like MLPPP, MLFR, and CRTP. It is not a configurable interface.

lt-0/0/0

Interface used to provide class-of-service (CoS) support for real-time performance monitoring (RPM) probe packets.

Within a J-series device, packets are routed to this internal interface for services. The lt interface is an internal interface only and is not associated with a physical medium or PIM. You must configure the interface for it to perform CoS for RPM services.

Note: The lt interface on the M-series and T-series routing platforms supports configuration of logical devices—the capability to partition a single physical device into multiple logical devices that perform independent routing tasks. However, the lt interface on the J-series device does not support logical devices.

pc-pim/0/0

Internally configured interface used by the system as a control path between the WXC Integrated Services Module and the Routing Engine.

pd-0/0/0

Configurable Protocol Independent Multicast (PIM) de-encapsulation interface. In PIM sparse mode, the first-hop routing platform encapsulates packets destined for the rendezvous point device. The packets are encapsulated with a unicast header and are forwarded through a unicast tunnel to the rendezvous point. The rendezvous point then de-encapsulates the packets and transmits them through its multicast tree.

Within a J-series device, packets are routed to this internal interface for de-encapsulation. The PIM de-encapsulation interface is an internal interface only and is not associated with a physical medium or Physical Interface Module (PIM). You must configure the interface for it to perform PIM de-encapsulation.

pe-0/0/0

Configurable Protocol Independent Multicast (PIM) encapsulation interface. In PIM sparse mode, the first-hop routing platform encapsulates packets destined for the rendezvous point device. The packets are encapsulated with a unicast header and are forwarded through a unicast tunnel to the rendezvous point. The rendezvous point then de-encapsulates the packets and transmits them through its multicast tree.

Within a J-series device, packets are routed to this internal interface for encapsulation. The PIM encapsulation interface is an internal interface only and is not associated with a physical medium or Physical Interface Module (PIM). You must configure the interface for it to perform PIM encapsulation.

pimd

Internally generated Protocol Independent Multicast (PIM) de-encapsulation interface. This interface is generated by the JUNOS software to handle PIM de-encapsulation. It is not a configurable interface.

pime

Internally generated Protocol Independent Multicast (PIM) encapsulation interface. This interface is generated by the JUNOS software to handle PIM encapsulation. It is not a configurable interface.

pp0

Configurable PPPoE encapsulation interface. PPP packets being routed in an Ethernet network use PPPoE encapsulation.

Within a J-series device, packets are routed to this internal interface for PPPoE encapsulation. The PPPoE encapsulation interface is an internal interface only and is not associated with a physical medium or PIM. You must configure the interface for it to forward PPPoE traffic. For more information about PPPoE interfaces, see Configuring Point-to-Point Protocol over Ethernet.

st0

Secure tunnel interface used for IPSec VPNs.

tap

Internally generated interface. This interface is generated by the JUNOS software to monitor and record traffic during passive monitoring. When packets are discarded by the Packet Forwarding Engine, they are placed on this interface. It is not a configurable interface.

umd0

Configurable USB modem physical interface. This interface is detected when an USB modem is connected to the USB port on the device.

Note: The J4350 and J6350 devices have two USB ports. However, you can connect only one USB modem to the USB ports on these devices. If you connect USB modems to both the USB ports, only the first USB modem connected to the device is recognized.