Cisco ASR 1000 Series Software Configuration Guide

The interface MTU value on the ATM SPA also determines which packets are recorded as “giants” in the
show interfaces atm command. The interface considers a packet to be a giant packet when it is more than
24 bytes larger than the interface MTU size. For example, if using an MTU size of 1500 bytes, the interface
increments the giants counter when it receives a packet larger than 1524 bytes.
Note
Interface MTU Configuration Task
To change the MTU values on the ATM SPA interfaces, use the following procedure beginning in global
configuration mode:
SUMMARY STEPS
1.
Do one of the following:
•
Router(config)# interface atm slot/subslot/port
•
•
Router(config)# interface atm slot/subslot/port.subinterface
2.
Router(config-if)# mtu bytes
3.
Router(config-if)# ip mtu bytes
4.
Router(config-if)# mpls mtu bytes
5.
Router(config-if)# end
DETAILED STEPS
PurposeCommand or Action
Enters interface configuration mode for the indicated port on the specified ATM
SPA, where:
Do one of the following:
Step 1
•
Router(config)# interface atm
slot/subslot/port
• 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.
•
Router(config)# interface atm
slot/subslot/port.subinterface
• port —Specifies the number of the individual interface port on a SPA.
• subinterface —Specifies the number of the subinterface.
(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
Router(config-if)# mtu bytes
Step 2
4470 bytes. As a general rule, do not change the MTU value unless you have a
specific application need to do so.
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.
Note
Cisco ASR 1000 Series Aggregation Services Routers SIP and SPA Software Configuration Guide, Cisco IOS
XE Everest 16.5
64 OL-14127-17
Configuring the ATM SPAs
Modifying the Interface MTU Size

Cisco ASR 1000 Series Specifications

General

Brand	Cisco
Model	ASR 1000 Series
Category	Network Router
Language	English