43
Configuring Interfaces
Configuring the System MTU
To remove an IP address from an interface, use the
no ip address
interface configuration command.
This example shows how to configure a port as a routed port and to assign it an IP address:
Switch#
configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#
interface GigabitEthernet1/18
Switch(config-if)#
no switchport
Switch(config-if)#
ip address 192.20.135.21 255.255.255.0
Configuring the System MTU
The default maximum transmission unit (MTU) size for frames received and sent on all interfaces on the switch is 1500
bytes. You can increase the MTU size for all interfaces operating at 10 or 100 Mbps by using the
system mtu
global
configuration command. You can increase the MTU size to support jumbo frames on all Gigabit Ethernet interfaces by
using the
system mtu jumbo
global configuration command. You can change the MTU size for routed ports by using the
system mtu routing
global configuration command.
Note:
You cannot configure a routing MTU size that exceeds the system MTU size. If you change the system MTU size
to a value smaller than the currently configured routing MTU size, the configuration change is accepted, but not applied
until the next switch reset. When the configuration change takes effect, the routing MTU size automatically defaults to
the new system MTU size.
Gigabit Ethernet ports are not affected by the
system mtu
command. Fast Ethernet ports are not affected by the
system
mtu jumbo
command because jumbo frames are not supported on 10/100 interfaces, including 100BASE-FX and
100BASE-BX SFP modules. If you do not configure the
system mtu jumbo
command, the setting of the
system mtu
command applies to all Gigabit Ethernet interfaces.
You cannot set the MTU size for an individual interface; you set it for all 10/100 or all Gigabit Ethernet interfaces on the
switch. When you change the system MTU size, you must reset the switch before the new configuration takes effect. The
system mtu routing
command does not require a switch reset to take effect.
Note:
The system MTU setting is saved in the switch environmental variable in NVRAM and becomes effective when the
switch reloads. The MTU settings you enter with the
system mtu
and
system mtu jumbo
commands are not saved in
the switch IOS configuration file, even if you enter the
copy running-config startup-config
privileged EXEC command.
Therefore, if you use TFTP to configure a new switch by using a backup configuration file and want the system MTU to
be other than the default, you must explicitly configure the
system mtu
and
system mtu jumbo
settings on the new
switch and then reload the switch.
Frames sizes that can be received by the switch CPU are limited to 1998 bytes, no matter what value was entered with
the
system mtu
or
system mtu jumbo
commands. Although frames that are forwarded or routed are typically not
received by the CPU, in some cases packets are sent to the CPU, such as traffic sent to control traffic, SNMP, Telnet, or
routing protocols.
Because the switch does not fragment packets, it drops:
switched packets larger than the packet size supported on the
egress
interface
7.
end
Return to privileged EXEC mode.
8.
show interfaces
[
interface-id
]
show ip interface
[
interface-id
]
show running-config interface
[
interface-id
]
Verify the configuration.
9.
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Command
Purpose
Содержание IE 4000
Страница 12: ...8 Configuration Overview Default Settings After Initial Switch Configuration ...
Страница 52: ...48 Configuring Interfaces Monitoring and Maintaining the Interfaces ...
Страница 108: ...104 Configuring Switch Clusters Additional References ...
Страница 128: ...124 Performing Switch Administration Additional References ...
Страница 130: ...126 Configuring PTP ...
Страница 140: ...136 Configuring CIP Additional References ...
Страница 146: ...142 Configuring SDM Templates Configuration Examples for Configuring SDM Templates ...
Страница 192: ...188 Configuring Switch Based Authentication Additional References ...
Страница 244: ...240 Configuring IEEE 802 1x Port Based Authentication Additional References ...
Страница 274: ...270 Configuring SGT Exchange Protocol over TCP SXP and Layer 3 Transport Configuring Cisco TrustSec Caching ...
Страница 298: ...294 Configuring VLANs Additional References ...
Страница 336: ...332 Configuring STP Additional References ...
Страница 408: ...404 Configuring DHCP Additional References ...
Страница 450: ...446 Configuring IGMP Snooping and MVR Additional References ...
Страница 490: ...486 Configuring SPAN and RSPAN Additional References ...
Страница 502: ...498 Configuring Layer 2 NAT ...
Страница 559: ...555 Configuring Network Security with ACLs How to Configure Network Security with ACLs Creating a Numbered Extended ACL ...
Страница 770: ...766 Configuring IPv6 MLD Snooping Related Documents ...
Страница 930: ...926 Configuring IP Unicast Routing Related Documents ...
Страница 956: ...952 Configuring IPv6 Unicast Routing Configuring IPv6 network 2010 AB8 2 48 network 2010 AB8 3 48 exit address family ...
Страница 976: ...972 Configuring Cisco IOS IP SLAs Operations Additional References ...
Страница 978: ...974 Dying Gasp ...
Страница 990: ...986 Configuring Enhanced Object Tracking Monitoring Enhanced Object Tracking ...
Страница 994: ...990 Configuring MODBUS TCP Displaying MODBUS TCP Information ...
Страница 996: ...992 Ethernet CFM ...
Страница 1030: ...1026 Working with the Cisco IOS File System Configuration Files and Software Images Working with Software Images ...
Страница 1066: ...1062 Using an SD Card SD Card Alarms ...