Cisco ASR 1000 Configuration Guide

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Cisco ASR 1000 Series Aggregation Services Routers SIP and SPA Software Configuration Guide
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Chapter 7 Configuring the ATM SPAs
Configuration Tasks
Interface MTU Configuration Task
To change the MTU values on the ATM SPA interfaces, use the following procedure beginning in global
configuration mode:
Verifying the MTU Size
To verify the MTU sizes for an interface, use the show interfaces, show ip interface, and show mpls
interface commands, as in the following examples:
Note The output of the show interfaces atm command can display configuration of AAL5 encapsulation, but
only AAL0 is supported on the Cisco ASR 1000 Series Routers.
Command or Action Purpose
Step 1
Router(config)# interface atm slot/subslot/port
or
Router(config)# interface atm
slot/subslot/port.subinterface
Enters interface configuration mode for the indicated port on
the specified ATM SPA, where:
• slot—Specifies the chassis slot number in the Cisco ASR
1000 Series Router where the SIP is installed.
• subslot—Specifies the secondary slot of the SIP where
the SPA is installed.
• port—Specifies the number of the individual interface
port on a SPA.
• subinterface—Specifies the number of the subinterface.
Step 2
Router(config-if)# mtu bytes (Optional) Configures the maximum transmission unit
(MTU) size for the interface. The valid range for bytes is
from 64 to 9216 bytes, with a default of 4470 bytes. As a
general rule, do not change the MTU value unless you have a
specific application need to do so.
Note If the IP MTU or MPLS MTU values are currently
the same size as the interface MTU, changing the
interface MTU size also automatically sets the IP
MTU or MPLS MTU values to the same value.
Step 3
Router(config-if)# ip mtu bytes (Optional) Configures the MTU value, in bytes, for IP
packets on this interface. The valid range for an ATM SPA is
64 to 9288, with a default value equal to the MTU value
configured in Step 2.
Step 4
Router(config-if)# mpls mtu bytes (Optional) Configures the MTU value, in bytes, for
MPLS-labeled packets on this interface. The valid range for
an ATM SPA is 64 to 9216 bytes, with a default value equal
to the MTU value configured in Step 2.
Note Repeat Step 1 through Step 4 for each port on the ATM SPA to be configured.
Step 5
Router(config-if)# end Exits interface configuration mode and returns to privileged
EXEC mode.

Cisco ASR 1000 Specifications

General

Brand	Cisco
Model	ASR 1000
Category	Network Router
Language	English