cisco 640 802 ccna portable command guide 2008 phần 7 doc

Saving VLAN Configurations 119
NOTE: When the switchport mode access command is used, the port
operates as a nontrunking, single VLAN interface that transmits and receives
nonencapsulated frames.
An access port can belong to only one VLAN.
Using the range Command
Verifying VLAN Information
Saving VLAN Configurations
The configurations of VLANs 1 through 1005 are always saved in the VLAN database. As
long as the apply or the exit command is executed in VLAN database mode, changes are
saved. If you are using VLAN configuration mode, the exit command saves the changes to
the VLAN database, too.
Switch(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee

rr
rr
aa
aa
nn
nn
gg
gg
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr

rr
nn
nn
ee
ee
tt
tt


00
00
//
//
11
11






99
99
Enables you to set the same configuration
parameters on multiple ports at the same
time.
NOTE: There is a space before and after
the hyphen in the interface range
command.
Switch(config-if-range)#ss

ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


mm
mm
oo
oo
dd
dd
ee
ee

aa
aa
cc
cc
cc
cc
ee
ee
ss
ss
ss
ss
Sets ports 1–9 as access ports.
Switch(config-if-range)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo

rr
rr
tt
tt


aa
aa
cc
cc
cc
cc
ee
ee
ss
ss
ss
ss


vv
vv
ll
ll
aa
aa
nn
nn

11
11
00
00
Assigns ports 1–9 to VLAN 10.
Switch#ss
ss
hh
hh
oo
oo
ww
ww


vv
vv
ll
ll
aa
aa
nn
nn
Displays VLAN information
Switch#ss
ss
hh
hh
oo
oo

ww
ww


vv
vv
ll
ll
aa
aa
nn
nn


bb
bb
rr
rr
ii
ii
ee
ee
ff
ff
Displays VLAN information in brief
Switch#ss
ss
hh
hh
oo

oo
ww
ww


vv
vv
ll
ll
aa
aa
nn
nn


ii
ii
dd
dd


22
22
Displays information about VLAN 2 only
Switch#ss
ss
hh
hh
oo
oo

ww
ww


vv
vv
ll
ll
aa
aa
nn
nn


nn
nn
aa
aa
mm
mm
ee
ee


mm
mm
aa
aa
rr
rr

kk
kk
ee
ee
tt
tt
ii
ii
nn
nn
gg
gg
Displays information about VLAN named
marketing only
Switch#ss
ss
hh
hh
oo
oo
ww
ww


ii
ii
nn
nn
tt
tt

ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ss
ss


vv
vv
ll
ll
aa
aa
nn
nn

x
Displays interface characteristics for the
specified VLAN
120 Erasing VLAN Configurations
If the VLAN database configuration is used at startup, and the startup configuration

file contains extended-range VLAN configuration, this information is lost when the system
boots.
If you are using VTP transparent mode, the configurations are also saved in the running
configuration and can be saved to the startup configuration using the copy running-config
startup-config command.
If the VTP mode is transparent in the startup configuration, and the VLAN database and the
VTP domain name from the VLAN database matches that in the startup configuration file,
the VLAN database is ignored (cleared), and the VTP and VLAN configurations in the
startup configuration file are used. The VLAN database revision number remains
unchanged in the VLAN database.
Erasing VLAN Configurations
Switch#dd
dd
ee
ee
ll
ll
ee
ee
tt
tt
ee
ee


ff
ff
ll
ll
aa

aa
ss
ss
hh
hh
::
::
vv
vv
ll
ll
aa
aa
nn
nn


dd
dd
aa
aa
tt
tt
Removes the entire VLAN database from flash.
WARNING: Make sure there is no space
between the colon (:) and the characters vlan.dat.
You can potentially erase the entire contents of
the flash with this command if the syntax is not
correct. Make sure you read the output from the
switch. If you need to cancel, press Ç-C to

escape back to privileged mode:
(Switch#)
Switch#dd
dd
ee
ee
ll
ll
ee
ee
tt
tt
ee
ee


ff
ff
ll
ll
aa
aa
ss
ss
hh
hh
::
::
vv
vv

ll
ll
aa
aa
nn
nn


dd
dd
aa
aa
tt
tt
Delete filename [vlan.dat]?
Delete flash:vlan.dat? [confirm]
Switch#
Switch(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa

aa
cc
cc
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt

tt


00
00
//
//
55
55
Moves to interface configuration mode.
Switch(config-if)#nn
nn
oo
oo


ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp

oo
oo
rr
rr
tt
tt


aa
aa
cc
cc
cc
cc
ee
ee
ss
ss
ss
ss


vv
vv
ll
ll
aa
aa
nn
nn

55
55
Removes port from VLAN 5 and reassigns it to
VLAN 1—the default VLAN.
Switch(config-if)#ee
ee
xx
xx
ii
ii
tt
tt
Moves to global configuration mode.
Switch(config)#nn
nn
oo
oo


vv
vv
ll
ll
aa
aa
nn
nn

55
55
Removes VLAN 5 from the VLAN database.
Or
Switch#vv
vv
ll
ll
aa
aa
nn
nn


dd
dd
aa
aa
tt
tt
aa
aa
bb
bb
aa
aa
ss
ss
ee

ee
Enters VLAN database mode.
Switch(vlan)#nn
nn
oo
oo


vv
vv
ll
ll
aa
aa
nn
nn


55
55
Removes VLAN 5 from the VLAN database.
Switch(vlan)#ee
ee
xx
xx
ii
ii
tt
tt
Applies changes, increases the revision number

by 1, and exits VLAN database mode.
Configuration Example: VLANs 121
NOTE: When you delete a VLAN from a switch that is in VTP server mode, the
VLAN is removed from the VLAN database for all switches in the VTP domain.
When you delete a VLAN from a switch that is in VTP transparent mode, the
VLAN is deleted only on that specific switch.
NOTE: You cannot delete the default VLANs for the different media types:
Ethernet VLAN 1 and FDDI or Token Ring VLANs 1002 to 1005.
CAUTION: When you delete a VLAN, any ports assigned to that VLAN become
inactive. They remain associated with the VLAN (and thus inactive) until you
assign them to a new VLAN. Therefore, it is recommended that you reassign
ports to a new VLAN or the default VLAN before you delete a VLAN from the
VLAN database.
Configuration Example: VLANs
Figure 12-1 illustrates the network topology for the configuration that follows, which shows
how to configure VLANs using the commands covered in this chapter.
Figure 12-2 Network Topology for VLAN Configuration Example
2960
10.1.30.10/24
WS1
Native
VLAN 1
10.1.1.0/24
Ports: 1-8
10.1.10.0/24
Ports: 9-15
10.1.20.0/24
Engineering
VLAN 30
Admin

VLAN 10
Accounting
VLAN 20
Ports: 16-24
10.1.30.0/24
122 Configuration Example: VLANs
2960 Switch
Switch>ee
ee
nn
nn
aa
aa
bb
bb
ll
ll
ee
ee
Moves to privileged mode.
Switch#cc
cc
oo
oo
nn
nn
ff
ff
ii
ii

gg
gg
uu
uu
rr
rr
ee
ee


tt
tt
ee
ee
rr
rr
mm
mm
ii
ii
nn
nn
aa
aa
ll
ll
Moves to global configuration mode.
Switch(config)#hh
hh
oo

oo
ss
ss
tt
tt
nn
nn
aa
aa
mm
mm
ee
ee


22
22
99
99
66
66
00
00
Sets the host name.
2960(config)#vv
vv
ll
ll
aa
aa

nn
nn


11
11
00
00
Creates VLAN 10 and enters VLAN
configuration mode.
2960(config-vlan)#nn
nn
aa
aa
mm
mm
ee
ee


AA
AA
dd
dd
mm
mm
ii
ii
nn
nn

Assigns a name to the VLAN.
2960(config-vlan)#ee
ee
xx
xx
ii
ii
tt
tt
Increases the revision number by 1 and
returns to global configuration mode.
2960(config)#vv
vv
ll
ll
aa
aa
nn
nn


22
22
00
00
Creates VLAN 20 and enters VLAN
configuration mode.
2960(config-vlan)#nn
nn
aa

aa
mm
mm
ee
ee


AA
AA
cc
cc
cc
cc
oo
oo
uu
uu
nn
nn
tt
tt
ii
ii
nn
nn
gg
gg
Assigns a name to the VLAN.
2960(config-vlan)#vv
vv

ll
ll
aa
aa
nn
nn


33
33
00
00
Creates VLAN 30 and enters VLAN
configuration mode. Note that you do not
have to exit back to global configuration
mode to execute this command.
2960(config-vlan)#nn
nn
aa
aa
mm
mm
ee
ee


EE
EE
nn
nn

gg
gg
ii
ii
nn
nn
ee
ee
ee
ee
rr
rr
ii
ii
nn
nn
gg
gg
Assigns a name to the VLAN.
2960(config-vlan)#ee
ee
xx
xx
ii
ii
tt
tt
Increases the revision number by 1 and
returns to global configuration mode.
2960(config)#ii

ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


rr
rr
aa
aa
nn
nn
gg
gg
ee
ee

ff
ff
aa
aa
ss
ss
tt
tt
hh
hh
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00

00
//
//
11
11


––
––


88
88
Enables you to set the same configuration
parameters on multiple ports at the same
time.
2960(config-if-range)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp

oo
oo
rr
rr
tt
tt


mm
mm
oo
oo
dd
dd
ee
ee


aa
aa
cc
cc
cc
cc
ee
ee
ss
ss
ss
ss

Sets ports 1–8 as access ports.
2960(config-if-range)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


aa
aa
cc
cc
cc
cc
ee

ee
ss
ss
ss
ss


vv
vv
ll
ll
aa
aa
nn
nn


11
11
00
00
Assigns ports 1–8 to VLAN 10.
2960(config-if-range)#ii
ii
nn
nn
tt
tt
ee
ee

rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


rr
rr
aa
aa
nn
nn
gg
gg
ee
ee


ff
ff
aa
aa
ss
ss

tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
99
99


––
––

11
11
55
55
Enables you to set the same configuration
parameters on multiple ports at the same
time.
2960(config-if-range)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt

mm
mm
oo
oo
dd
dd
ee
ee


aa
aa
cc
cc
cc
cc
ee
ee
ss
ss
ss
ss
Sets ports 9–15 as access ports.
2960(config-if-range)#ss
ss
ww
ww
ii
ii

tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


aa
aa
cc
cc
cc
cc
ee
ee
ss
ss
ss
ss

vv
vv
ll
ll
aa
aa
nn
nn


22
22
00
00
Assigns ports 9–15 to VLAN 20.
Configuration Example: VLANs 123
2960(config-if-range)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa

cc
cc
ee
ee


rr
rr
aa
aa
nn
nn
gg
gg
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt

hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
11
11
66
66






22
22

44
44
Enables you to set the same configuration
parameters on multiple ports at the same
time.
2960(config-if-range)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


mm
mm
oo

oo
dd
dd
ee
ee


aa
aa
cc
cc
cc
cc
ee
ee
ss
ss
ss
ss
Sets ports 16–24 as access ports.
2960(config-if-range)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc

hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


aa
aa
cc
cc
cc
cc
ee
ee
ss
ss
ss
ss


vv
vv
ll
ll

aa
aa
nn
nn


33
33
00
00
Assigns ports 16–24 to VLAN 30.
2960(config-if-range)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode.
2960(config)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to privileged mode.
2960#cc

cc
oo
oo
pp
pp
yy
yy


rr
rr
uu
uu
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg


cc
cc
oo
oo
nn

nn
ff
ff
ii
ii
gg
gg


ss
ss
tt
tt
aa
aa
rr
rr
tt
tt
uu
uu
pp
pp


cc
cc
oo
oo
nn

nn
ff
ff
ii
ii
gg
gg
Saves the configuration in NVRAM.
This page intentionally left blank
CHAPTER 13
VLAN Trunking Protocol
and Inter-VLAN Routing
This chapter provides information and commands concerning the following topics:
• Dynamic Trunking Protocol (DTP)
• Setting the encapsulation type
• VLAN Trunking Protocol (VTP)
— Using global configuration mode
— Using VLAN database mode
• Verifying VTP
• Inter-VLAN communication using an external router: Router-on-a-stick
• Inter-VLAN communication tips
• Configuration example: Inter-VLAN communication
Dynamic Trunking Protocol (DTP)
Switch (config)##
##
ii
ii
nn
nn
tt

tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee

ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
11
11
Moves to interface configuration mode.
Switch(config-if)
##
##
ss
ss
ww
ww
ii
ii
tt
tt
cc

cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


mm
mm
oo
oo
dd
dd
ee
ee


dd
dd
yy
yy
nn
nn
aa

aa
mm
mm
ii
ii
cc
cc


dd
dd
ee
ee
ss
ss
ii
ii
rr
rr
aa
aa
bb
bb
ll
ll
ee
ee
Makes the interface actively attempt to
convert the link to a trunk link.
NOTE: With the switchport mode dynamic

desirable command set, the interface
becomes a trunk link if the neighboring
interface is set to trunk, desirable, or auto.
Switch(config-if)
##
##
ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


mm
mm

oo
oo
dd
dd
ee
ee


dd
dd
yy
yy
nn
nn
aa
aa
mm
mm
ii
ii
cc
cc


aa
aa
uu
uu
tt
tt

oo
oo
Makes the interface able to convert into a
trunk link.
NOTE: With the switchport mode dynamic
auto command set, the interface becomes a
trunk link if the neighboring interface is set to
trunk or desirable.
Switch(config-if)
##
##
ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt

tt


nn
nn
oo
oo
nn
nn
ee
ee
gg
gg
oo
oo
tt
tt
ii
ii
aa
aa
tt
tt
ee
ee
Prevents the interface from generating DTP
frames.
126 Setting the Encapsulation Type
TIP: The default mode is dependent on the platform. For the 2960, the default
mode is dynamic auto.

TIP: On a 2960 switch, the default for all ports is to be an access port. However,
with the default DTP mode being dynamic auto, an access port can be converted
into a trunk port if that port receives DTP information from the other side of
the link if that side is set to trunk or desirable. It is therefore recommended to hard-
code all access ports as access ports with the switchport mode access command.
This way, DTP information will not inadvertently change an access port to a
trunk port. Any port set with the switchport mode access command ignores any
DTP requests to convert the link.
Setting the Encapsulation Type
Depending on the series of switch that you are using, you might have a choice as to what
type of VLAN encapsulation you want to use: the Cisco proprietary Inter-Switch Link (ISL)
or the IEEE Standard 802.1q (dot1q). The 2960 switch supports only dot1q trunking.
NOTE: Use the switchport mode
nonegotiate command only when the
interface switchport mode is access or trunk.
You must manually configure the neighboring
interface to establish a trunk link.
Switch(config-if)
##
##
ss
ss
ww
ww
ii
ii
tt
tt
cc
cc

hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


mm
mm
oo
oo
dd
dd
ee
ee


tt
tt
rr
rr
uu
uu
nn
nn

kk
kk
Puts the interface into permanent trunking
mode and negotiates to convert the link into a
trunk link.
NOTE: With the switchport mode trunk
command set, the interface becomes a trunk
link even if the neighboring interface is not a
trunk link.
3560Switch(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


ff

ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
11

11
Moves to interface configuration mode
3560Switch(config-if)
#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


mm
mm
oo
oo
dd

dd
ee
ee


tt
tt
rr
rr
uu
uu
nn
nn
kk
kk
Puts the interface into permanent trunking
mode and negotiates to convert the link into a
trunk link
3560Switch(config-if)
#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh

hh
pp
pp
oo
oo
rr
rr
tt
tt


tt
tt
rr
rr
uu
uu
nn
nn
kk
kk

ee
ee
nn
nn
cc
cc
aa
aa

pp
pp
ss
ss
uu
uu
ll
ll
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn


ii
ii
ss
ss
ll
ll
Specifies ISL encapsulation on the trunk link
3560Switch(config-if)
#ss
ss

ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


tt
tt
rr
rr
uu
uu
nn
nn
kk
kk

ee
ee
nn
nn
cc
cc
aa
aa
pp
pp
ss
ss
uu
uu
ll
ll
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn

dd
dd
oo
oo
tt
tt
11
11
qq
qq
Specifies 802.1q encapsulation on the trunk
link
VLAN Trunking Protocol (VTP) 127
TIP: With the switchport trunk encapsulation negotiate command set, the
preferred trunking method is ISL.
CAUTION: The 2960 series switch supports only dot1q trunking.
VLAN Trunking Protocol (VTP)
VTP is a Cisco proprietary protocol that allows for VLAN configuration (addition, deletion,
or renaming of VLANs) to be consistently maintained across a common administrative
domain.
Using Global Configuration Mode
3560Switch(config-if)
#ss
ss
ww
ww
ii
ii
tt
tt

cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


tt
tt
rr
rr
uu
uu
nn
nn
kk
kk


ee
ee
nn
nn

cc
cc
aa
aa
pp
pp
ss
ss
uu
uu
ll
ll
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn


nn
nn
ee
ee
gg
gg

oo
oo
tt
tt
ii
ii
aa
aa
tt
tt
ee
ee
Specifies that the interface negotiate with
the neighboring interface to become either
an ISL or dot1q trunk, depending on the
capabilities or configuration of the
neighboring interface
Switch(config)#vv
vv
tt
tt
pp
pp


mm
mm
oo
oo
dd

dd
ee
ee


cc
cc
ll
ll
ii
ii
ee
ee
nn
nn
tt
tt
Changes the switch to VTP client mode.
Switch(config)#vv
vv
tt
tt
pp
pp


mm
mm
oo
oo

dd
dd
ee
ee


ss
ss
ee
ee
rr
rr
vv
vv
ee
ee
rr
rr
Changes the switch to VTP server mode.
Switch(config)#vv
vv
tt
tt
pp
pp


mm
mm
oo

oo
dd
dd
ee
ee


tt
tt
rr
rr
aa
aa
nn
nn
ss
ss
pp
pp
aa
aa
rr
rr
ee
ee
nn
nn
tt
tt
Changes the switch to VTP transparent mode.

NOTE: By default, all Catalyst switches are in
server mode.
Switch(config)#nn
nn
oo
oo


vv
vv
tt
tt
pp
pp


mm
mm
oo
oo
dd
dd
ee
ee
Returns the switch to the default VTP server
mode.
Switch(config)#vv
vv
tt
tt

pp
pp


dd
dd
oo
oo
mm
mm
aa
aa
ii
ii
nn
nn

domain-name
Configures the VTP domain name. The name
can be from 1 to 32 characters long.
NOTE: All switches operating in VTP server or
client mode must have the same domain name
to ensure communication.
Switch(config)#vv
vv
tt
tt
pp
pp

pp
pp
aa
aa
ss
ss
ss
ss
ww
ww
oo
oo
rr
rr
dd
dd

password
Configures a VTP password. In Cisco IOS
Software Release 12.3 and later, the password is
an ASCII string from 1 to 32 characters long. If
you are using a Cisco IOS Software release
earlier than 12.3, the password length ranges
from 8 to 64 characters long.
128 VLAN Trunking Protocol (VTP)
NOTE: Only VLANs included in the pruning-eligible list can be pruned. VLANs 2
through 1001 are pruning eligible by default on trunk ports. Reserved VLANs
and extended-range VLANs cannot be pruned. To change which eligible
VLANs can be pruned, use the interface-specific switchport trunk pruning

vlan command:
Switch(config-if)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


tt
tt
rr
rr
uu
uu
nn

nn
kk
kk


pp
pp
rr
rr
uu
uu
nn
nn
ii
ii
nn
nn
gg
gg


vv
vv
ll
ll
aa
aa
nn
nn

rr
rr
ee
ee
mm
mm
oo
oo
vv
vv
ee
ee


44
44
,,
,,


22
22
00
00


33
33
00

00
! Removes VLANs 4 and 20-30
Switch(config-if)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


tt
tt
rr
rr
uu
uu

nn
nn
kk
kk


pp
pp
rr
rr
uu
uu
nn
nn
ii
ii
nn
nn
gg
gg


vv
vv
ll
ll
aa
aa
nn
nn

ee
ee
xx
xx
cc
cc
ee
ee
pp
pp
tt
tt


44
44
00
00


55
55
00
00
! All VLANs are added to the pruning list except for 40-50
Using VLAN Database Mode
CAUTION: The VLAN database mode has been deprecated and will be removed
in some future Cisco IOS release. Recommended practice dictates using only

the VLAN configuration mode.
NOTE: To communicate with each other, all
switches must have the same VTP password set.
Switch(config)#vv
vv
tt
tt
pp
pp


vv
vv
22
22


mm
mm
oo
oo
dd
dd
ee
ee
Sets the VTP domain to Version 2. This
command is for Cisco IOS Software Release
12.3 and later. If you are using a Cisco IOS
Software release earlier than 12.3, the command
is vtp version 2.

NOTE: VTP Versions 1 and 2 are not
interoperable. All switches must use the same
version. The biggest difference between
Versions 1 and 2 is that Version 2 has support
for Token Ring VLANs.
Switch(config)#vv
vv
tt
tt
pp
pp


pp
pp
rr
rr
uu
uu
nn
nn
ii
ii
nn
nn
gg
gg
Enables VTP pruning.
NOTE: By default, VTP pruning is disabled.
You need to enable VTP pruning on only

1 switch in VTP server mode.
Switch##
##
vv
vv
ll
ll
aa
aa
nn
nn


dd
dd
aa
aa
tt
tt
aa
aa
bb
bb
aa
aa
ss
ss
ee
ee
Enters VLAN database mode.

Switch(vlan)##
##
vv
vv
tt
tt
pp
pp


cc
cc
ll
ll
ii
ii
ee
ee
nn
nn
tt
tt
Changes the switch to VTP client mode.
Switch(vlan)##
##
vv
vv
tt
tt
pp

pp


ss
ss
ee
ee
rr
rr
vv
vv
ee
ee
rr
rr
Changes the switch to VTP server mode.
Switch(vlan)##
##
vv
vv
tt
tt
pp
pp


tt
tt
rr
rr

aa
aa
nn
nn
ss
ss
pp
pp
aa
aa
rr
rr
ee
ee
nn
nn
tt
tt
Changes the switch to VTP transparent mode.
NOTE: By default, all Catalyst switches are in server
mode.
VLAN Trunking Protocol (VTP) 129
Switch(vlan)##
##
vv
vv
tt
tt
pp
pp

dd
dd
oo
oo
mm
mm
aa
aa
ii
ii
nn
nn


dd
dd
oo
oo
mm
mm
aa
aa
ii
ii
nn
nn

nn
nn
aa
aa
mm
mm
ee
ee
Configures the VTP domain name. The name can be
from 1 to 32 characters long.
NOTE: All switches operating in VTP server or client
mode must have the same domain name to ensure
communication.
Switch(vlan)##
##
vv
vv
tt
tt
pp
pp


pp
pp
aa
aa
ss
ss
ss

ss
ww
ww
oo
oo
rr
rr
dd
dd


pp
pp
aa
aa
ss
ss
ss
ss
ww
ww
oo
oo
rr
rr
dd
dd
Configures a VTP password. In Cisco IOS Software
Release 12.3 and later, the password is an ASCII string
from 1 to 32 characters long. If you are using a Cisco

IOS release earlier than 12.3, the password length
ranges from 8 to 64 characters long.
NOTE: All switches must have the same VTP
password set to communicate with each other.
Switch(vlan)##
##
vv
vv
tt
tt
pp
pp


vv
vv
22
22


mm
mm
oo
oo
dd
dd
ee
ee
Sets the VTP domain to Version 2. This command is
for Cisco IOS Release 12.3 and later. If you are using a

Cisco IOS release earlier than 12.3, the command is
vtp version 2.
NOTE: VTP Versions 1 and 2 are not interoperable.
All switches must use the same version. The
biggest difference between Versions 1 and 2 is that
Version 2 has support for Token Ring VLANs.
Switch(vlan)##
##
vv
vv
tt
tt
pp
pp


pp
pp
rr
rr
uu
uu
nn
nn
ii
ii
nn
nn
gg
gg

Enables VTP pruning.
NOTE: By default, VTP pruning is disabled. You
need to enable VTP pruning on only one switch in
VTP server mode.
NOTE: Only VLANs included in the pruning-eligible
list can be pruned. VLANs 2 through 1001 are pruning
eligible by default on trunk ports. Reserved VLANs
and extended-range VLANs cannot be pruned. To
change which eligible VLANs can be pruned, use the
interface-specific switchport trunk pruning vlan
command:
Switch(config-if)##
##
ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr

rr
tt
tt


tt
tt
rr
rr
uu
uu
nn
nn
kk
kk


pp
pp
rr
rr
uu
uu
nn
nn
ii
ii
nn
nn
gg

gg


vv
vv
ll
ll
aa
aa
nn
nn


rr
rr
ee
ee
mm
mm
oo
oo
vv
vv
ee
ee


44
44
,,

,,


22
22
00
00


33
33
00
00
Removes VLANs 4 and 20 through 30.
Switch(config-if)##
##
ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp

oo
oo
rr
rr
tt
tt


tt
tt
rr
rr
uu
uu
nn
nn
kk
kk


pp
pp
rr
rr
uu
uu
nn
nn
ii
ii

nn
nn
gg
gg


vv
vv
ll
ll
aa
aa
nn
nn


ee
ee
xx
xx
cc
cc
ee
ee
pp
pp
tt
tt

44
44
00
00


55
55
00
00
All VLANs are added to the pruning list except for 40
through 50.
Switch(vlan)##
##
ee
ee
xx
xx
ii
ii
tt
tt
Applies changes to the VLAN database, increases the
revision number by 1, and exits back to privileged
mode.
130 Inter-VLAN Communication Using an External Router: Router-on-a-Stick
Verifying VTP
NOTE: If trunking has been established before VTP is set up, VTP information
is propagated throughout the switch fabric almost immediately. However,
because VTP information is advertised only every 300 seconds (5 minutes),

unless a change has been made to force an update, it can take several minutes
for VTP information to be propagated.
Inter-VLAN Communication Using an External Router:
Router-on-a-Stick
Switch#ss
ss
hh
hh
oo
oo
ww
ww


vv
vv
tt
tt
pp
pp


ss
ss
tt
tt
aa
aa
tt
tt

uu
uu
ss
ss
Displays general information about VTP configuration
Switch#ss
ss
hh
hh
oo
oo
ww
ww


vv
vv
tt
tt
pp
pp


cc
cc
oo
oo
uu
uu
nn

nn
tt
tt
ee
ee
rr
rr
ss
ss
Displays the VTP counters for the switch
Router(config)##
##
ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee

ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00

//
//
00
00
Moves to interface configuration mode.
Router(config-if)##
##
dd
dd
uu
uu
pp
pp
ll
ll
ee
ee
xx
xx


ff
ff
uu
uu
ll
ll
ll
ll
Sets the interface to full duplex.

Router(config-if)##
##
nn
nn
oo
oo


ss
ss
hh
hh
uu
uu
tt
tt
dd
dd
oo
oo
ww
ww
nn
nn
Enables the interface.
Router(config-if)##
##
ii
ii
nn

nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh

hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
00
00


11
11
Creates subinterface 0/0.1 and moves to
subinterface configuration mode.
Router(config-subif)##
##
dd
dd
ee

ee
ss
ss
cc
cc
rr
rr
ii
ii
pp
pp
tt
tt
ii
ii
oo
oo
nn
nn


MM
MM
aa
aa
nn
nn
aa
aa
gg

gg
ee
ee
mm
mm
ee
ee
nn
nn
tt
tt


VV
VV
LL
LL
AA
AA
NN
NN


11
11
(Optional) Sets the locally significant
description of the subinterface.
Router(config-subif)
##
##

ee
ee
nn
nn
cc
cc
aa
aa
pp
pp
ss
ss
uu
uu
ll
ll
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn


dd
dd

oo
oo
tt
tt
11
11
qq
qq


11
11


nn
nn
aa
aa
tt
tt
ii
ii
vv
vv
ee
ee
Assigns VLAN 1 to this subinterface.
VLAN 1 will be the native VLAN. This
subinterface will use the 802.1q trunking
protocol.

Router(config-subif)##
##
ii
ii
pp
pp


aa
aa
dd
dd
dd
dd
rr
rr
ee
ee
ss
ss
ss
ss


11
11
99
99
22
22

11
11
66
66
88
88


11
11


11
11


22
22
55
55
55
55


22
22
55
55

55
55


22
22
55
55
55
55


00
00
Assigns the IP address and netmask.
Router(config-subif)##
##
ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa

aa
cc
cc
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt

tt


00
00
//
//
00
00


11
11
00
00
Creates subinterface 0/0.10 and moves to
subinterface configuration mode.
Router(config-subif)##
##
dd
dd
ee
ee
ss
ss
cc
cc
rr
rr
ii

ii
pp
pp
tt
tt
ii
ii
oo
oo
nn
nn


AA
AA
cc
cc
cc
cc
oo
oo
uu
uu
nn
nn
tt
tt
ii
ii
nn

nn
gg
gg


VV
VV
LL
LL
AA
AA
NN
NN


11
11
00
00
(Optional) Sets the locally significant
description of the subinterface.
Router(config-subif)
##
##
ee
ee
nn
nn
cc
cc

aa
aa
pp
pp
ss
ss
uu
uu
ll
ll
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn


dd
dd
oo
oo
tt
tt
11
11

qq
qq


11
11
00
00

Assigns VLAN 10 to this subinterface. This
subinterface will use the 802.1q trunking
protocol.
Inter-VLAN Communication Tips 131
NOTE: The subnets of the VLANs are directly connected to the router. Routing
between these subnets does not require a dynamic routing protocol. In a more
complex topology, these routes need to either be advertised with whatever
dynamic routing protocol is being used or be redistributed into whatever dynamic
routing protocol is being used.
NOTE: Routes to the subnets associated with these VLANs appear in the routing
table as directly connected networks.
Inter-VLAN Communication Tips
• Although most routers support both ISL and dot1q encapsulation, some switch models
only support dot1q (the 2950 and 2960 series, for example).
• If you need to use ISL as your trunking protocol, use the command encapsulation isl
x, where x is the number of the VLAN to be assigned to that subinterface.
• Recommended best practice is to use the same number of the VLAN number for the
subinterface number. It is easier to troubleshoot VLAN 10 on subinterface fa0/0.10
than on fa0/0.2.
• The native VLAN (usually VLAN 1) cannot be configured on a subinterface for Cisco
IOS Software releases that are earlier than 12.1(3)T. Native VLAN IP addresses

therefore need to be configured on the physical interface. Other VLAN traffic is
configured on subinterfaces:
Router(config)#interface fastethernet 0/0
Router(config-if)#encapsulation dot1q 1 native
Router(config-if)#ip address 192.168.1.1 255.255.255.0
Router(config-if)#interface fastethernet 0/0.10
Router(config-subif)#encapsulation dot1q 10
Router(config-subif)#ip address 192.168.10.1 255.255.255.0
Router(config-subif)##
##
ii
ii
pp
pp


aa
aa
dd
dd
dd
dd
rr
rr
ee
ee
ss
ss
ss
ss

11
11
99
99
22
22


11
11
66
66
88
88


11
11
00
00


11
11


22
22

55
55
55
55


22
22
55
55
55
55


22
22
55
55
55
55


00
00
Assigns the IP address and netmask.
Router(config-subif)##
##
ee
ee
xx

xx
ii
ii
tt
tt
Returns to interface configuration mode.
Router(config-if)##
##
ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode.
Router(config)##
##
132 Configuration Example: Inter-VLAN Communication
Configuration Example: Inter-VLAN Communication
Figure 13-1 illustrates the network topology for the configuration that follows, which shows
how to configure inter-VLAN communication using commands covered in this chapter.
Some commands used in this configuration are from previous chapters.
Figure 13-3 Network Topology for Inter-VLAN Communication Configuration
L2Switch1
192.168.10.10/24
WS1
Sales
VLAN 10

fa0/2-4
192.168.10.0/24
192.168.20.20/24
WS2
Engineering
VLAN 20
fa0/5-8
192.168.20.0/24
192.168.30.30/24
WS3
Marketing
VLAN 30
fa0/9-12
192.168.30.0/24
Internet
Native
VLAN 1
fa0/2-4
192.168.1.0/24
VLAN 1
192.168.1.2/24
IEEE 802.1q
Trunk
s0/0/0
192.31.7.6/30
Lo 0
198.133.219.1/24
s0/0/0 DCE
192.31.7.5/30
fa0/0 – no IP address

fa0/00.1 – VLAN 1 (Native) - 192.168.1.1/24
fa0/0.10 – VLAN 10 - 192.168.10.1/24
fa0/0.20 – VLAN 20 - 192.168.20.1/24
fa0/0.30 – VLAN 30- 192.168.30.1/24
CORP
ISP
2960
fa0/1
Configuration Example: Inter-VLAN Communication 133
ISP Router
Router>ee
ee
nn
nn
aa
aa
bb
bb
ll
ll
ee
ee
Moves to privileged mode
Router>#cc
cc
oo
oo
nn
nn
ff

ff
ii
ii
gg
gg
uu
uu
rr
rr
ee
ee


tt
tt
ee
ee
rr
rr
mm
mm
ii
ii
nn
nn
aa
aa
ll
ll
Moves to global configuration mode

Router(config)#hh
hh
oo
oo
ss
ss
tt
tt
nn
nn
aa
aa
mm
mm
ee
ee


II
II
SS
SS
PP
PP
Sets the host name
ISP(config)#ii
ii
nn
nn
tt

tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


ll
ll
oo
oo
oo
oo
pp
pp
bb
bb
aa
aa
cc
cc
kk

kk


00
00
Moves to interface configuration mode
ISP(config-if)#dd
dd
ee
ee
ss
ss
cc
cc
rr
rr
ii
ii
pp
pp
tt
tt
ii
ii
oo
oo
nn
nn

ss
ss
ii
ii
mm
mm
uu
uu
ll
ll
aa
aa
tt
tt
ee
ee
dd
dd


aa
aa
dd
dd
dd
dd
rr
rr
ee
ee

ss
ss
ss
ss


rr
rr
ee
ee
pp
pp
rr
rr
ee
ee
ss
ss
ee
ee
nn
nn
tt
tt
ii
ii
nn
nn
gg
gg

rr
rr
ee
ee
mm
mm
oo
oo
tt
tt
ee
ee


ww
ww
ee
ee
bb
bb
ss
ss
ii
ii
tt
tt
ee
ee

Sets the locally significant interface
description
ISP(config-if)#ii
ii
pp
pp


aa
aa
dd
dd
dd
dd
rr
rr
ee
ee
ss
ss
ss
ss


11
11
99
99
88
88

11
11
33
33
33
33


22
22
11
11
99
99


11
11


22
22
55
55
55
55

22
22
55
55
55
55


22
22
55
55
55
55


00
00
Assigns the IP address and netmask
ISP(config-if)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff

ff
aa
aa
cc
cc
ee
ee


ss
ss
ee
ee
rr
rr
ii
ii
aa
aa
ll
ll


00
00
//
//
00
00
//

//
00
00
Moves to interface configuration mode
ISP(config-if)#dd
dd
ee
ee
ss
ss
cc
cc
rr
rr
ii
ii
pp
pp
tt
tt
ii
ii
oo
oo
nn
nn


WW
WW

AA
AA
NN
NN


ll
ll
ii
ii
nn
nn
kk
kk


tt
tt
oo
oo


tt
tt
hh
hh
ee
ee

CC
CC
oo
oo
rr
rr
pp
pp
oo
oo
rr
rr
aa
aa
tt
tt
ee
ee


RR
RR
oo
oo
uu
uu
tt
tt
ee
ee

rr
rr
Sets the locally significant interface
description
ISP(config-if)#ii
ii
pp
pp


aa
aa
dd
dd
dd
dd
rr
rr
ee
ee
ss
ss
ss
ss


11
11
99
99

22
22


33
33
11
11


77
77


55
55


22
22
55
55
55
55


22
22
55
55

55
55


22
22
55
55
55
55


22
22
55
55
22
22
Assigns the IP address and netmask
ISP(config-if)#cc
cc
ll
ll
oo
oo
cc
cc
kk
kk

rr
rr
aa
aa
tt
tt
ee
ee


55
55
66
66
00
00
00
00
00
00
Assigns a clock rate to the interface—the
DCE cable is plugged into this interface
ISP(config-if)#nn
nn
oo
oo


ss

ss
hh
hh
uu
uu
tt
tt
dd
dd
oo
oo
ww
ww
nn
nn
Enables the interface
ISP(config-if)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode
ISP(config-if)#rr
rr
oo
oo
uu

uu
tt
tt
ee
ee
rr
rr


ee
ee
ii
ii
gg
gg
rr
rr
pp
pp


11
11
00
00
Creates Enhanced Interior Gateway Routing
Protocol (EIGRP) routing process 10
ISP(config-router)#nn
nn
ee

ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk


11
11
99
99
88
88


11
11
33
33
33
33


22

22
11
11
99
99


00
00
Advertises directly connected networks
(classful address only)
ISP(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk


11
11
99

99
22
22


33
33
11
11


77
77


00
00
Advertises directly connected networks
(classful address only)
ISP(config-router)#nn
nn
oo
oo


aa
aa
uu
uu
tt

tt
oo
oo


ss
ss
uu
uu
mm
mm
mm
mm
aa
aa
rr
rr
yy
yy
Disables auto summarization
ISP(config-router)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode
ISP(config)#ee

ee
xx
xx
ii
ii
tt
tt
Returns to privileged mode
ISP#cc
cc
oo
oo
pp
pp
yy
yy


rr
rr
uu
uu
nn
nn
nn
nn
ii
ii
nn
nn

gg
gg


cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg


ss
ss
tt
tt
aa
aa
rr
rr
tt
tt
uu
uu

pp
pp


cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
Saves the configuration to NVRAM
134 Configuration Example: Inter-VLAN Communication
CORP Router
Router>ee
ee
nn
nn
aa
aa
bb
bb
ll
ll
ee

ee
Moves to privileged mode.
Router>#cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
uu
uu
rr
rr
ee
ee


tt
tt
ee
ee
rr
rr
mm
mm

ii
ii
nn
nn
aa
aa
ll
ll
Moves to global configuration mode.
Router(config)#hh
hh
oo
oo
ss
ss
tt
tt
nn
nn
aa
aa
mm
mm
ee
ee


CC
CC
OO

OO
RR
RR
PP
PP
Sets the host name.
CORP(config)#nn
nn
oo
oo


ii
ii
pp
pp


dd
dd
oo
oo
mm
mm
aa
aa
ii
ii
nn
nn

ll
ll
oo
oo
oo
oo
kk
kk
uu
uu
pp
pp
Turns off Domain Name System (DNS)
resolution to avoid wait time due to DNS
lookup of spelling errors.
CORP(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa

aa
cc
cc
ee
ee


ss
ss
ee
ee
rr
rr
ii
ii
aa
aa
ll
ll


00
00
//
//
00
00
//
//
00

00
Moves to interface configuration mode.
CORP(config-if)#dd
dd
ee
ee
ss
ss
cc
cc
rr
rr
ii
ii
pp
pp
tt
tt
ii
ii
oo
oo
nn
nn


ll
ll
ii
ii

nn
nn
kk
kk


tt
tt
oo
oo


II
II
SS
SS
PP
PP
Sets the locally significant interface
description.
CORP(config-if)#ii
ii
pp
pp


aa
aa
dd
dd

dd
dd
rr
rr
ee
ee
ss
ss
ss
ss


11
11
99
99
22
22


33
33
11
11


77
77

66
66


22
22
55
55
55
55


22
22
55
55
55
55


22
22
55
55
55
55


22
22

55
55
22
22
Assigns the IP address and netmask.
CORP(config-if)#nn
nn
oo
oo


ss
ss
hh
hh
uu
uu
tt
tt
dd
dd
oo
oo
ww
ww
nn
nn
Enables the interface.
CORP(config-if)#ee
ee

xx
xx
ii
ii
tt
tt
Returns to global configuration mode.
CORP(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


ff
ff
aa

aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
00
00
Enters interface configuration mode.

CORP(config-if)#dd
dd
uu
uu
pp
pp
ll
ll
ee
ee
xx
xx


ff
ff
uu
uu
ll
ll
ll
ll
Enables full-duplex operation to ensure
trunking takes effect between here and
L2Switch1.
CORP(config-if)#nn
nn
oo
oo

ss
ss
hh
hh
uu
uu
tt
tt
dd
dd
oo
oo
ww
ww
nn
nn
Enables the interface.
CORP(config-if)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff

aa
aa
cc
cc
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee

tt
tt


00
00
//
//
00
00


11
11
Creates a virtual subinterface and moves
to subinterface configuration mode.
CORP(config-subif)#dd
dd
ee
ee
ss
ss
cc
cc
rr
rr
ii
ii
pp
pp

tt
tt
ii
ii
oo
oo
nn
nn


MM
MM
aa
aa
nn
nn
aa
aa
gg
gg
ee
ee
mm
mm
ee
ee
nn
nn
tt
tt

VV
VV
LL
LL
AA
AA
NN
NN


11
11


––
––


NN
NN
aa
aa
tt
tt
ii
ii
vv
vv

ee
ee


VV
VV
LL
LL
AA
AA
NN
NN
Sets the locally significant interface
description.
CORP(config-subif)#ee
ee
nn
nn
cc
cc
aa
aa
pp
pp
ss
ss
uu
uu
ll
ll

aa
aa
tt
tt
ii
ii
oo
oo
nn
nn


dd
dd
oo
oo
tt
tt
11
11
qq
qq


11
11


nn
nn

aa
aa
tt
tt
ii
ii
vv
vv
ee
ee
Assigns VLAN 1 to this subinterface.
VLAN 1 will be the native VLAN. This
subinterface will use the 802.1q trunking
protocol.
CORP(config-subif)#ii
ii
pp
pp


aa
aa
dd
dd
dd
dd
rr
rr
ee
ee

ss
ss
ss
ss


11
11
99
99
22
22


11
11
66
66
88
88


11
11


11
11

22
22
55
55
55
55


22
22
55
55
55
55


22
22
55
55
55
55


00
00
Assigns the IP address and netmask.
CORP(config-subif)#ii
ii
nn

nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh

hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
00
00


11
11
00
00
Creates a virtual subinterface and moves
to subinterface configuration mode.
Configuration Example: Inter-VLAN Communication 135
CORP(config-subif)#dd
dd

ee
ee
ss
ss
cc
cc
rr
rr
ii
ii
pp
pp
tt
tt
ii
ii
oo
oo
nn
nn


SS
SS
aa
aa
ll
ll
ee
ee

ss
ss


VV
VV
LL
LL
AA
AA
NN
NN


11
11
00
00
Sets the locally significant interface
description.
CORP(config-subif)#ee
ee
nn
nn
cc
cc
aa
aa
pp
pp

ss
ss
uu
uu
ll
ll
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn


dd
dd
oo
oo
tt
tt
11
11
qq
qq

11
11
00
00

Assigns VLAN 10 to this subinterface.
This subinterface will use the 802.1q
trunking protocol.
CORP(config-subif)#ii
ii
pp
pp


aa
aa
dd
dd
dd
dd
rr
rr
ee
ee
ss
ss
ss
ss

11
11
99
99
22
22


11
11
66
66
88
88


11
11
00
00


11
11


22
22
55
55

55
55


22
22
55
55
55
55


22
22
55
55
55
55


00
00
Assigns the IP address and netmask.
CORP(config-subif)#ii
ii
nn
nn
tt
tt
ee

ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr

rr
nn
nn
ee
ee
tt
tt


00
00
//
//
00
00


22
22
00
00
Creates a virtual subinterface and moves
to subinterface configuration mode.
CORP(config-subif)#dd
dd
ee
ee
ss
ss
cc

cc
rr
rr
ii
ii
pp
pp
tt
tt
ii
ii
oo
oo
nn
nn


EE
EE
nn
nn
gg
gg
ii
ii
nn
nn
ee
ee
ee

ee
rr
rr
ii
ii
nn
nn
gg
gg


VV
VV
LL
LL
AA
AA
NN
NN


22
22
00
00
Sets the locally significant interface
description.
CORP(config-subif)#ee
ee
nn

nn
cc
cc
aa
aa
pp
pp
ss
ss
uu
uu
ll
ll
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn


dd
dd
oo
oo
tt

tt
11
11
qq
qq


22
22
00
00
Assigns VLAN 20 to this subinterface.
This subinterface will use the 802.1q
trunking protocol.
CORP(config-subif)#ii
ii
pp
pp


aa
aa
dd
dd
dd
dd
rr
rr
ee
ee

ss
ss
ss
ss


11
11
99
99
22
22


11
11
66
66
88
88


22
22
00
00


11
11

22
22
55
55
55
55


22
22
55
55
55
55


22
22
55
55
55
55


00
00
Assigns the IP address and netmask.
CORP(config-subif)#ii

ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt

tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
00
00


33
33
00
00
Creates a virtual subinterface and moves
to subinterface configuration mode.
CORP(config-subif)#dd

dd
ee
ee
ss
ss
cc
cc
rr
rr
ii
ii
pp
pp
tt
tt
ii
ii
oo
oo
nn
nn


MM
MM
aa
aa
rr
rr
kk

kk
ee
ee
tt
tt
ii
ii
nn
nn
gg
gg


VV
VV
LL
LL
AA
AA
NN
NN


33
33
00
00
Sets the locally significant interface
description.
CORP(config-subif)#ee

ee
nn
nn
cc
cc
aa
aa
pp
pp
ss
ss
uu
uu
ll
ll
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn


dd
dd
oo

oo
tt
tt
11
11
qq
qq


33
33
00
00
Assigns VLAN 30 to this subinterface.
This subinterface will use the 802.1q
trunking protocol.
CORP(config-subif)#ii
ii
pp
pp


aa
aa
dd
dd
dd
dd

11
11
99
99
22
22


11
11
66
66
88
88


33
33
00
00


11
11


22
22
55
55

55
55


22
22
55
55
55
55


22
22
55
55
55
55


00
00
Assigns the IP address and netmask.
CORP(config-subif)#ee
ee
xx
xx
ii
ii
tt

tt
Returns to interface configuration mode.
CORP(config-if)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode.
CORP(config)#rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr


ee
ee
ii
ii
gg

gg
rr
rr
pp
pp


11
11
00
00
Creates EIGRP routing process 10 and
moves to router configuration mode.
CORP(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk


11

11
99
99
22
22


11
11
66
66
88
88


11
11


00
00
Advertises the 192.168.1.0 network.
CORP(config-router)#nn
nn
ee
ee
tt
tt
ww
ww

oo
oo
rr
rr
kk
kk


11
11
99
99
22
22


11
11
66
66
88
88


11
11
00
00

00
00
Advertises the 192.168.10.0 network.
CORP(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk


11
11
99
99
22
22


11
11
66

66
88
88


22
22
00
00


00
00
Advertises the 192.168.20.0 network.
136 Configuration Example: Inter-VLAN Communication
L2Switch1 (Catalyst 2960)
CORP(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk

11
11
99
99
22
22


11
11
66
66
88
88


33
33
00
00


00
00
Advertises the 192.168.30.0 network.
CORP(config-router)#nn
nn
ee

ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk


11
11
99
99
22
22


33
33
11
11


77
77

00
00
Advertises the 192.31.7.0 network.
CORP(config-router)#nn
nn
oo
oo


aa
aa
uu
uu
tt
tt
oo
oo


ss
ss
uu
uu
mm
mm
mm
mm
aa
aa

rr
rr
yy
yy
Turns off automatic summarization at the
classful boundary.
CORP(config-router)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode.
CORP(config)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to privileged mode.
CORP#cc
cc
oo
oo
pp
pp

yy
yy


rr
rr
uu
uu
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg


cc
cc
oo
oo
nn
nn
ff
ff
ii
ii

gg
gg


ss
ss
tt
tt
aa
aa
rr
rr
tt
tt
uu
uu
pp
pp


cc
cc
oo
oo
nn
nn
ff
ff
ii
ii

gg
gg
Saves the configuration in NVRAM.
Switch>ee
ee
nn
nn
aa
aa
bb
bb
ll
ll
ee
ee
Moves to privileged mode.
Switch#cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
uu
uu

rr
rr
ee
ee


tt
tt
ee
ee
rr
rr
mm
mm
ii
ii
nn
nn
aa
aa
ll
ll
Moves to global configuration mode.
Switch(config)#hh
hh
oo
oo
ss
ss
tt

tt
nn
nn
aa
aa
mm
mm
ee
ee


LL
LL
22
22
SS
SS
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
11
11
Sets the host name.

L2Switch1(config)#nn
nn
oo
oo


ii
ii
pp
pp


dd
dd
oo
oo
mm
mm
aa
aa
ii
ii
nn
nn


ll
ll
oo
oo

oo
oo
kk
kk
uu
uu
pp
pp
Turns off DNS resolution.
L2Switch1(config)#vv
vv
ll
ll
aa
aa
nn
nn


11
11
00
00
Creates VLAN 10 and enters VLAN
configuration mode.
L2Switch1(config-vlan)#nn
nn
aa
aa
mm

mm
ee
ee


SS
SS
aa
aa
ll
ll
ee
ee
ss
ss
Assigns a name to the VLAN.
L2Switch1(config-vlan)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode.
L2Switch1(config)#vv
vv
ll
ll
aa

aa
nn
nn


22
22
00
00
Creates VLAN 20 and enters VLAN
configuration mode.
L2Switch1(config-vlan)#nn
nn
aa
aa
mm
mm
ee
ee


EE
EE
nn
nn
gg
gg
ii
ii
nn

nn
ee
ee
ee
ee
rr
rr
ii
ii
nn
nn
gg
gg
Assigns a name to the VLAN.
L2Switch1(config-vlan)#vv
vv
ll
ll
aa
aa
nn
nn


33
33
00
00
Creates VLAN 30 and enters VLAN
configuration mode. Note that you do

not have to exit back to global
configuration mode to execute this
command.
L2Switch1(config-vlan)#nn
nn
aa
aa
mm
mm
ee
ee


MM
MM
aa
aa
rr
rr
kk
kk
ee
ee
tt
tt
ii
ii
nn
nn
gg

gg
Assigns a name to the VLAN.
L2Switch1(config-vlan)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode.
Configuration Example: Inter-VLAN Communication 137
L2Switch1(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee

rr
rr
aa
aa
nn
nn
gg
gg
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee

rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
22
22


––
––


44
44
Enables you to set the same
configuration parameters on multiple
ports at the same time.
L2Switch1(config-if-range)#ss
ss
ww

ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


mm
mm
oo
oo
dd
dd
ee
ee


aa

aa
cc
cc
cc
cc
ee
ee
ss
ss
ss
ss
Sets ports 2–4 as access ports.
L2Switch1(config-if-range)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr

tt
tt


aa
aa
cc
cc
cc
cc
ee
ee
ss
ss
ss
ss


vv
vv
ll
ll
aa
aa
nn
nn


11
11

00
00
Assigns ports 2–4 to VLAN 10.
L2Switch1(config-if-range)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


rr
rr
aa
aa
nn
nn
gg

gg
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt

00
00
//
//
55
55


––
––


88
88
Enables you to set the same
configuration parameters on multiple
ports at the same time.
L2Switch1(config-if-range)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh

pp
pp
oo
oo
rr
rr
tt
tt


mm
mm
oo
oo
dd
dd
ee
ee


aa
aa
cc
cc
cc
cc
ee
ee
ss
ss

ss
ss
Sets ports 5–8 as access ports.
L2Switch1(config-if-range)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


aa
aa
cc
cc
cc

cc
ee
ee
ss
ss
ss
ss


vv
vv
ll
ll
aa
aa
nn
nn


22
22
00
00
Assigns ports 5–8 to VLAN 20.
L2Switch1(config-if-range)#ii
ii
nn
nn
tt
tt

ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


rr
rr
aa
aa
nn
nn
gg
gg
ee
ee


ff
ff
aa
aa

ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
99
99

11
11
22
22
Enables you to set the same
configuration parameters on multiple
ports at the same time
L2Switch1(config-if-range)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt

tt


mm
mm
oo
oo
dd
dd
ee
ee


aa
aa
cc
cc
cc
cc
ee
ee
ss
ss
ss
ss
Sets ports 9–12 as access ports.
L2Switch1(config-if-range)#ss
ss
ww
ww

ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


aa
aa
cc
cc
cc
cc
ee
ee
ss
ss
ss
ss

vv
vv
ll
ll
aa
aa
nn
nn


33
33
00
00
Assigns ports 9–12 to VLAN 30.
L2Switch1(config-if-range)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode.
L2Switch1(config)#ii
ii
nn
nn

tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh

ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
11
11
Moves to interface configuration
mode.
L2Switch1(config)#dd
dd
ee
ee
ss
ss
cc
cc
rr
rr

ii
ii
pp
pp
tt
tt
ii
ii
oo
oo
nn
nn


TT
TT
rr
rr
uu
uu
nn
nn
kk
kk


LL
LL
ii
ii

nn
nn
kk
kk


tt
tt
oo
oo


CC
CC
OO
OO
RR
RR
PP
PP


RR
RR
oo
oo
uu
uu
tt
tt

ee
ee
rr
rr
Sets the locally significant interface
description.
L2Switch1(config-if)#ss
ss
ww
ww
ii
ii
tt
tt
cc
cc
hh
hh
pp
pp
oo
oo
rr
rr
tt
tt


mm
mm

oo
oo
dd
dd
ee
ee


tt
tt
rr
rr
uu
uu
nn
nn
kk
kk
Puts the interface into trunking mode
and negotiates to convert the link into
a trunk link
L2Switch1(config-if)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode.

L2Switch1(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


vv
vv
ll
ll
aa
aa
nn
nn

11
11
Creates the virtual interface for
VLAN 1 and enters interface
configuration mode.
138 Configuration Example: Inter-VLAN Communication
L2Switch1(config-if)#ii
ii
pp
pp


aa
aa
dd
dd
dd
dd
rr
rr
ee
ee
ss
ss
ss
ss


11
11

99
99
22
22


11
11
66
66
88
88


11
11


22
22


22
22
55
55
55
55

22
22
55
55
55
55


22
22
55
55
55
55


00
00
Assigns the IP address and netmask.
L2Switch1(config-if)#nn
nn
oo
oo


ss
ss
hh
hh
uu

uu
tt
tt
dd
dd
oo
oo
ww
ww
nn
nn
Enables the interface.
L2Switch1(config-if)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode.
L2Switch1(config)#ii
ii
pp
pp


dd
dd
ee

ee
ff
ff
aa
aa
uu
uu
ll
ll
tt
tt


gg
gg
aa
aa
tt
tt
ee
ee
ww
ww
aa
aa
yy
yy


11

11
99
99
22
22


11
11
66
66
88
88


11
11


11
11
Assigns the default gateway address.
L2Switch1(config)#ee
ee
xx
xx
ii
ii
tt
tt

Returns to privileged mode.
L2Switch1#cc
cc
oo
oo
pp
pp
yy
yy


rr
rr
uu
uu
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg


cc
cc
oo

oo
nn
nn
ff
ff
ii
ii
gg
gg


ss
ss
tt
tt
aa
aa
rr
rr
tt
tt
uu
uu
pp
pp


cc
cc
oo

oo
nn
nn
ff
ff
ii
ii
gg
gg
Saves the configuration in NVRAM.
CHAPTER 14
STP and
EtherChannel
This chapter provides information and commands concerning the following topics:
• Spanning Tree Protocol
— Enabling Spanning Tree Protocol
— Configuring the root switch
— Configuring a secondary root switch
— Configuring port priority
— Configuring the path cost
— Configuring the switch priority of a VLAN
— Configuring STP timers
— Verifying STP
— Optional STP configurations
— Changing the spanning-tree mode
— Extended System ID
— Enabling Rapid Spanning Tree
— Troubleshooting Spanning Tree
— Configuration example: STP
• EtherChannel

— Interface modes in EtherChannel
— Guidelines for configuring EtherChannel
— Configuring Layer 2 EtherChannel
— Verifying EtherChannel
— Configuration example: EtherChannel
Spanning Tree Protocol
Enabling Spanning Tree Protocol
Switch(config)#ss
ss
pp
pp
aa
aa
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg


tt
tt
rr
rr
ee

ee
ee
ee


vv
vv
ll
ll
aa
aa
nn
nn


55
55
Enables STP on VLAN 5
Switch(config)#nn
nn
oo
oo


ss
ss
pp
pp
aa
aa

nn
nn
nn
nn
ii
ii
nn
nn
gg
gg


tt
tt
rr
rr
ee
ee
ee
ee


vv
vv
ll
ll
aa
aa
nn
nn

55
55
Disables STP on VLAN 5
140 Spanning Tree Protocol
NOTE: If more VLANs are defined in the VLAN Trunking Protocol (VTP) than
there are spanning-tree instances, you can only have STP on 64 VLANs. If you
have more than 128 VLANs, it is recommended that you use Multiple STP.
Configuring the Root Switch
Switch(config)#ss
ss
pp
pp
aa
aa
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg


tt
tt

rr
rr
ee
ee
ee
ee


vv
vv
ll
ll
aa
aa
nn
nn


55
55


rr
rr
oo
oo
oo
oo
tt
tt

Modifies the switch priority from the
default 32768 to a lower value to allow
the switch to become the root switch for
VLAN 5.
NOTE: If all other switches have
extended system ID support, this switch
resets its priority to 24576. If any other
switch has a priority set to below 24576
already, this switch sets its own priority
to 4096 less than the lowest switch
priority. If by doing this the switch
would have a priority of less than 1, this
command fails.
Switch(config)#ss
ss
pp
pp
aa
aa
nn
nn
nn
nn
ii
ii
nn
nn
gg

gg


tt
tt
rr
rr
ee
ee
ee
ee


vv
vv
ll
ll
aa
aa
nn
nn


55
55


rr
rr
oo

oo
oo
oo
tt
tt


pp
pp
rr
rr
ii
ii
mm
mm
aa
aa
rr
rr
yy
yy
Switch recalculates timers along with
priority to allow the switch to become
the root switch for VLAN 5.
TIP: The root switch should be a
backbone or distribution switch.
Switch(config)#ss
ss
pp
pp

aa
aa
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg


tt
tt
rr
rr
ee
ee
ee
ee


vv
vv
ll
ll
aa
aa

nn
nn


55
55


rr
rr
oo
oo
oo
oo
tt
tt


pp
pp
rr
rr
ii
ii
mm
mm
aa
aa
rr
rr

yy
yy


dd
dd
ii
ii
aa
aa
mm
mm
ee
ee
tt
tt
ee
ee
rr
rr


77
77
Configures the switch to be the root
switch for VLAN 5 and sets the network
diameter to 7.
TIP: The diameter keyword is used to
define the maximum number of switches
between any two end stations. The range

is from 2 to 7 switches.
Switch(config)#ss
ss
pp
pp
aa
aa
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg


tt
tt
rr
rr
ee
ee
ee
ee


vv

vv
ll
ll
aa
aa
nn
nn


55
55


rr
rr
oo
oo
oo
oo
tt
tt


pp
pp
rr
rr
ii
ii
mm

mm
aa
aa
rr
rr
yy
yy


hh
hh
ee
ee
ll
ll
ll
ll
oo
oo


tt
tt
ii
ii
mm
mm
ee
ee

44
44
Configures the switch to be the root
switch for VLAN 5 and sets the hello-
delay timer to 4 seconds.
TIP: The hello-time keyword sets the
hello-delay timer to any amount
between 1 and 10 seconds. The default
time is 2 seconds.
Spanning Tree Protocol 141
Configuring a Secondary Root Switch
Configuring Port Priority
Switch(config)#ss
ss
pp
pp
aa
aa
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg

tt
tt
rr
rr
ee
ee
ee
ee


vv
vv
ll
ll
aa
aa
nn
nn


55
55


rr
rr
oo
oo
oo

oo
tt
tt


ss
ss
ee
ee
cc
cc
oo
oo
nn
nn
dd
dd
aa
aa
rr
rr
yy
yy
Switch recalculates timers along with
priority to allow the switch to become
the root switch for VLAN 5 should the
primary root switch fail.
NOTE: If all other switches have
extended system ID support, this switch
resets its priority to 28672. Therefore, if

the root switch fails, and all other
switches are set to the default priority of
32768, this becomes the new root
switch. For switches without extended
system ID support, the switch priority is
changed to 16384.
Switch(config)#ss
ss
pp
pp
aa
aa
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg


tt
tt
rr
rr
ee
ee

ee
ee


vv
vv
ll
ll
aa
aa
nn
nn


55
55


rr
rr
oo
oo
oo
oo
tt
tt


ss
ss

ee
ee
cc
cc
oo
oo
nn
nn
dd
dd
aa
aa
rr
rr
yy
yy


dd
dd
ii
ii
aa
aa
mm
mm
ee
ee
tt
tt

ee
ee
rr
rr


77
77
Configures the switch to be the
secondary root switch for VLAN 5 and
sets the network diameter to 7.
Switch(config)#ss
ss
pp
pp
aa
aa
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg


tt

tt
rr
rr
ee
ee
ee
ee


vv
vv
ll
ll
aa
aa
nn
nn


55
55


rr
rr
oo
oo
oo
oo
tt

tt


ss
ss
ee
ee
cc
cc
oo
oo
nn
nn
dd
dd
aa
aa
rr
rr
yy
yy


hh
hh
ee
ee
ll
ll
ll

ll
oo
oo


tt
tt
ii
ii
mm
mm
ee
ee


44
44
Configures the switch to be the
secondary root switch for VLAN 5 and
sets the hello-delay timer to 4 seconds.
Switch(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr

ff
ff
aa
aa
cc
cc
ee
ee


gg
gg
ii
ii
gg
gg
aa
aa
bb
bb
ii
ii
tt
tt
ee
ee
tt
tt
hh
hh

ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
11
11
Moves to interface configuration mode.
Switch(config-if)#ss
ss
pp
pp
aa
aa
nn
nn
nn
nn
ii

ii
nn
nn
gg
gg


tt
tt
rr
rr
ee
ee
ee
ee


pp
pp
oo
oo
rr
rr
tt
tt


pp
pp
rr

rr
ii
ii
oo
oo
rr
rr
ii
ii
tt
tt
yy
yy


66
66
44
44
Configures the port priority for the
interface that is an access port.
Switch(config-if)#ss
ss
pp
pp
aa
aa
nn
nn
nn

nn
ii
ii
nn
nn
gg
gg


tt
tt
rr
rr
ee
ee
ee
ee


vv
vv
ll
ll
aa
aa
nn
nn


55

55


pp
pp
oo
oo
rr
rr
tt
tt


pp
pp
rr
rr
ii
ii
oo
oo
rr
rr
ii
ii
tt
tt
yy
yy

66
66
44
44
Configures the VLAN port priority for
an interface that is a trunk port.
NOTE: Port priority is used to break a
tie when 2 switches have equal
priorities for determining the root
switch. The number can be between 0
and 255. The default port priority is
128. The lower the number, the higher
the priority.
142 Spanning Tree Protocol
Configuring the Path Cost
Configuring the Switch Priority of a VLAN
NOTE: With the priority keyword, the range is 0 to 61440 in increments of 4096.
The default is 32768. The lower the priority, the more likely the switch will be
chosen as the root switch.
Only the following numbers can be used as a priority value:
CAUTION: Cisco recommends caution when using this command. Cisco further
recommends that the spanning-tree vlan x root primary or the spanning-tree
vlan x root secondary command be used instead to modify the switch priority.
Switch(config)#ii
ii
nn
nn
tt
tt

ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee


gg
gg
ii
ii
gg
gg
aa
aa
bb
bb
ii
ii
tt
tt
ee
ee

tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt


00
00
//
//
11
11
Moves to interface configuration mode.
Switch(config-if)#ss
ss
pp
pp
aa
aa
nn

nn
nn
nn
ii
ii
nn
nn
gg
gg


tt
tt
rr
rr
ee
ee
ee
ee


cc
cc
oo
oo
ss
ss
tt
tt

11
11
00
00
00
00
00
00
00
00
00
00
Configures the cost for the interface that is
an access port.
Switch(config-if)#ss
ss
pp
pp
aa
aa
nn
nn
nn
nn
ii
ii
nn
nn
gg

gg


tt
tt
rr
rr
ee
ee
ee
ee


vv
vv
ll
ll
aa
aa
nn
nn


55
55


cc
cc
oo

oo
ss
ss
tt
tt


11
11
00
00
00
00
00
00
00
00
00
00
00
00
Configures the VLAN cost for an interface
that is a trunk port.
NOTE: If a loop occurs, STP uses the
path cost when trying to determine which
interface to place into the forwarding state.
A higher path cost means a lower speed
transmission. The range of the cost
keyword is 1 through 200000000. The
default is based on the media speed of the

interface.
Switch(config)#ss
ss
pp
pp
aa
aa
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg


tt
tt
rr
rr
ee
ee
ee
ee


vv

vv
ll
ll
aa
aa
nn
nn


55
55


pp
pp
rr
rr
ii
ii
oo
oo
rr
rr
ii
ii
tt
tt
yy
yy

11
11
22
22
22
22
88
88
88
88
Configures the switch priority of
VLAN 5 to 12288
0 4096 8192 12288
16384 20480 24576 28672
32768 36864 40960 45056
49152 53248 57344 61440