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Configuring Interface Encapsulation on SONET/SDH Interfaces

 

You can configure encapsulation on a physical SONET/SDH interface and on a logical SONET/SDH interface. SONET/SDH interfaces can use either PPP or Cisco HDLC encapsulation. Use PPP if you are running Cisco IOS Release 12.0 or later. If you need to run Cisco HDLC, the Junos OS automatically configures an ISO family MTU of 4469 in the router. This is due to an extra byte of padding used by Cisco.

The following tasks explain configuring encapsulation on a physical SONET/SDH interface, configuring frame relay encapsulation on a logical SONET/SDH interface, and configuring Point-to-Point Protocol encapsulation to get a SONET/SDH OC3 or OC12 interface up and running:

Configuring the Encapsulation on a Physical SONET/SDH Interface

To configure encapsulation on a physical SONET/SDH interface:

  1. In configuration mode, go to the [edit interfaces so-fpc/pic/port] hierarchy level.
  2. Configure the encapsulation as cisco-hdlc, cisco-hdlc-ccc, cisco-hdlc-tcc, frame-relay, frame-relay-ccc, frame-relay-tcc, frame-relay-ether-type, frame-relay-ether-type-tcc, extended-frame-relay-ether-type-tcc, ppp, ppp-ccc, or as ppp-tcc.

When you configure a point-to-point encapsulation (such as PPP or Cisco HDLC) on a physical interface, the physical interface can have only one logical interface (that is, only one unit statement) associated with it. When you configure a multipoint encapsulation (such as Frame Relay), the physical interface can have multiple logical units, and the units can be either point to point or multipoint. Use PPP if you are running Cisco IOS Release 12.0 or later. If you need to run Cisco HDLC, the Junos OS automatically configures an ISO family MTU of 4469 in the router. This is due to an extra byte of padding used by Cisco.

Note

When the encapsulation type is set to Cisco-compatible Frame Relay encapsulation, ensure that the LMI type is set to ANSI or Q933-A.

For more information about physical interface encapsulation, see Configuring Interface Encapsulation on Physical Interfaces.

Displaying the Encapsulation on a Physical SONET/SDH Interface

Purpose

To display the configured encapsulation and its associated set options on a physical SONET/SDH interface when the following are set at the [edit interfaces interface-name] hierarchy level:

  • interface-name—so-7/0/0

  • Encapsulation—ppp

  • Unit—0

  • Family—inet

  • Address—192.168.1.113/32

  • Destination—192.168.1.114

  • Family—iso and mpls

Action

Run the show command at the [edit interfaces interface-name] hierarchy level.

Meaning

The configured encapsulation and its associated set options are displayed as expected. Note that the second set of two family statements allow IS-IS and MPLS to run on the interface.

Configuring the Frame Relay Encapsulation on a Logical SONET/SDH Interface

Generally, you configure an interface’s encapsulation at the [edit interfaces interface-name] hierarchy level. However, for Frame Relay encapsulation, you can also configure the encapsulation type that is used inside the Frame Relay packet itself.

To configure Frame Relay encapsulation on a logical SONET/SDH interface:

  1. In configuration mode, go to the [edit interfaces so-fpc/pic/port unit logical-unit-number] hierarchy level.
  2. Configure the encapsulation as frame-relay-ccc, frame-relay-tcc, frame-relay-ether-type, or as frame-relay-ether-type-tcc.

The ATM encapsulations are defined in RFC 2684, Multiprotocol Encapsulation over ATM Adaptation Layer 5.

For more information about logical interface encapsulation, see Configuring Interface Encapsulation on Logical Interfaces.

Configuring the Point-to-Point Protocol Encapsulation on a Physical SONET/SDH Interface

SONET/SDH interfaces can use either PPP or Cisco HDLC encapsulation. Use PPP if you are running Cisco IOS Release 12.0 or later. If you need to run Cisco HDLC, the Junos OS automatically configures an ISO family MTU of 4469 in the router. This is due to an extra byte of padding used by Cisco. The following configuration, which uses PPP encapsulation, is sufficient to get a SONET/SDH OC3 or OC12 interface up and running:

To configure PPP encapsulation on a physical SONET/SDH interface:

  1. In configuration mode, go to the [edit interfaces so-fpc/pic/port] hierarchy level.
  2. Configure the encapsulation as ppp.
  3. Configure local IP address and remote IP address with family inet.