Cisco 4G-LTE-ANTM-O-3 Installation Guide download pdf (Page 178)

The administrative state of a parent interface drives the state of the subinterface and its PVC. When the

administrative state of a parent interface or subinterface changes, so does the administrative state of any

child PVC configured under that parent interface or subinterface.

Note

To configure Frame Relay encapsulation on serial interfaces, use the encapsulation (Frame Relay VC-bundle)

command.

Frame Relay interfaces support two types of encapsulated frames:

•

Cisco (default)

•

IETF

Use the encap command in PVC configuration mode to configure Cisco or IETF encapsulation on a PVC. If

the encapsulation type is not configured explicitly for a PVC, then that PVC inherits the encapsulation type

from the main serial interface.

Cisco encapsulation is required on serial main interfaces that are configured for MPLS. IETF encapsulation

is not supported for MPLS.

Note

Before you configure Frame Relay encapsulation on an interface, you must verify that all prior Layer 3

configuration is removed from that interface. For example, you must ensure that there is no IP address

configured directly under the main interface; otherwise, any Frame Relay configuration done under the main

interface will not be viable.

LMI on Frame Relay Interfaces

The Local Management Interface (LMI) protocol monitors the addition, deletion, and status of PVCs. LMI

also verifies the integrity of the link that forms a Frame Relay UNI interface. By default, cisco LMI is enabled

on all PVCs.

If the LMI type is cisco (the default LMI type), the maximum number of PVCs that can be supported under

a single interface is related to the MTU size of the main interface. Use the following formula to calculate the

maximum number of PVCs supported on a card or SPA:

(MTU - 13)/8 = maximum number of PVCs

The default setting of the mtu command for a serial interface is 1504 bytes. Therefore, the default numbers

of PVCs supported on a serial interface configured with cisco LMI is 186.

Note

Configuring Serial Interfaces

This section contains the following tasks:

Cisco 800 Series Integrated Services Routers Software Configuration Guide

150 OL-31704-02

Configuring the Serial Interface

Configuring Serial Interfaces

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Cisco 4G-LTE-ANTM-O-3 Installation Guide Page 178