Solved: Not getting switchport trunk encapsulation option on cisco 4948e switch

tuhinbhowmick · ‎09-12-2012

Hi,

Trying to configurtie the cisco 4948e switch gigabitethernet port with "switchport trunk encapsulation dot1q", but didn't get the option. Please find below the options got after "swithport trunk"............

SW(config-if)#switchport trunk ?

allowed Set allowed VLAN characteristics when interface is in trunking mode

native Set trunking native characteristics when interface is in trunking mode

pruning Set pruning VLAN characteristics when interface is in trunking mode

SW(config-if)#switchport trunk

Please find below the version of the SW............

SW#sh ver

Cisco IOS Software, Catalyst 4500 L3 Switch Software (cat4500e-LANBASE-M), Versi

on 12.2(54)SG1, RELEASE SOFTWARE (fc1)

Technical Support: http://www.cisco.com/techsupport

Compiled Thu 27-Jan-11 12:24 by prod_rel_team

Image text-base: 0x10000000, data-base: 0x128316E0

ROM: 12.2(44r)SG11

Hobgoblin Revision 21, Fortooine Revision 1.22

GCC_Sify_HP_Tools_SW uptime is 56 minutes

System returned to ROM by power-on

System image file is "bootflash:cat4500e-lanbase-mz.122-54.SG1.bin"

cisco WS-C4948E (MPC8548) processor (revision 8) with 1048576K bytes of memory.

Processor board ID CAT1626S2YN

MPC8548 CPU at 1GHz, Cisco Catalyst 4948E

Last reset from PowerUp

3 Virtual Ethernet interfaces

48 Gigabit Ethernet interfaces

4 Ten Gigabit Ethernet interfaces

511K bytes of non-volatile configuration memory.

Configuration register is 0x2101

SW#

So, whether the command is not supporting on this cisco switch ? But we have cisco 4948 cisco sw where that command is working fine.

Regards,

Tuhin

Jon Marshall · ‎09-12-2012

Tuhin

Not dealt with the 4948e but people have faced the same issue with other models of switch. The reason you don't get a choice is probably because the switch only supports dot1q encapsulation so there is no choice to be made.

You would only get a choice if the switch supported both ISL and dot1q.

Jon

View solution in original post

Jon Marshall · ‎09-12-2012

Tuhin

Not dealt with the 4948e but people have faced the same issue with other models of switch. The reason you don't get a choice is probably because the switch only supports dot1q encapsulation so there is no choice to be made.

You would only get a choice if the switch supported both ISL and dot1q.

Jon

tuhinbhowmick · ‎09-12-2012

Hi Marshall,

I want to have that option "trunk enacpsulation dot1q" but on intreface of 4948e switch not getting the option "enacpsulation" after trunk.

As a result not able to use the switch port as "trunk" port.

Regards,

Tuhin

Peter Paluch · ‎09-12-2012

Tuhin,

Jon tried to explain that the 4948 switch has no switchport trunk encapsulation command because the only encapsulation it supports is IEEE 802.1Q. Therefore, it is a futile attempt to configure something like "trunk encapsulation dot1q" as you indicated - because that is implicitly configured anyway.

However, if you want to configure a port as a trunk port then a different command must be used:

switchport mode trunk

Best regards,

Peter

tuhinbhowmick · ‎09-13-2012

Hi Peter,

We have 4948 switch on our environment and where I am able to get the option of "Switchport trunk encapsulation dot1q" on interface. Please fine below the same for your reference.

SW3#sh ver

Cisco IOS Software, Catalyst 4500 L3 Switch Software (cat4500-IPBASE-M), Version

12.2(53)SG2, RELEASE SOFTWARE (fc1)

Technical Support: http://www.cisco.com/techsupport

Compiled Tue 16-Mar-10 00:54 by prod_rel_team

Image text-base: 0x10000000, data-base: 0x11B95764

ROM: 12.2(31r)SGA2

Dagobah Revision 226, Swamp Revision 5

GCCBLRDC-ACC-SW3 uptime is 4 weeks, 5 days, 4 hours, 3 minutes

System returned to ROM by power-on

System restarted at 04:56:45 UTC Sat Aug 11 2012

System image file is "bootflash:cat4500-ipbase-mz.122-53.SG2.bin"

cisco WS-C4948 (MPC8245) processor (revision 0) with 262144K bytes of memory.

Processor board ID FOX1410G1BD

MPC8245 CPU at 266Mhz, Fixed Module

Last reset from PowerUp

4 Virtual Ethernet interfaces

48 Gigabit Ethernet interfaces

511K bytes of non-volatile configuration memory.

Configuration register is 0x2101

SW3#

SW3(config-if)#switchport trunk ?

allowed Set allowed VLAN characteristics when interface is in trunking mode

encapsulation Set trunking encapsulation when interface is in trunking mode

native Set trunking native characteristics when interface is in trunking mode

pruning Set pruning VLAN characteristics when interface is in trunking mode

SW3(config-if)#switchport trunk encapsulation dot1q

Whereas we have bought new 4948e switch where I am not able to get the above mentioned option.Please find below the same for your reference.

SW#sh ver

Cisco IOS Software, Catalyst 4500 L3 Switch Software (cat4500e-LANBASE-M), Versi

on 12.2(54)SG1, RELEASE SOFTWARE (fc1)

Technical Support: http://www.cisco.com/techsupport

Compiled Thu 27-Jan-11 12:24 by prod_rel_team

Image text-base: 0x10000000, data-base: 0x128316E0

ROM: 12.2(44r)SG11

Hobgoblin Revision 21, Fortooine Revision 1.22

GCC_Sify_HP_Tools_SW uptime is 20 hours, 9 minutes

System returned to ROM by power-on

System image file is "bootflash:cat4500e-lanbase-mz.122-54.SG1.bin"

cisco WS-C4948E (MPC8548) processor (revision 8) with 1048576K bytes of memory.

Processor board ID CAT1626S2YN

MPC8548 CPU at 1GHz, Cisco Catalyst 4948E

Last reset from PowerUp

3 Virtual Ethernet interfaces

48 Gigabit Ethernet interfaces

4 Ten Gigabit Ethernet interfaces

511K bytes of non-volatile configuration memory.

Configuration register is 0x2101

SW#

SW(config-if)#switchport trunk ?

allowed Set allowed VLAN characteristics when interface is in trunking mode

native Set trunking native characteristics when interface is in trunking mode

pruning Set pruning VLAN characteristics when interface is in trunking mode

SW(config-if)#switchport trunk

SW(config-if)#switchport trunk encapsulation dot1q

^

% Invalid input detected at '^' marker.

SW(config-if)#

Kindly, suggest.

Regards,

Tuhin

Peter Paluch · ‎09-13-2012

Hello Tuhin,

A simple rule is: if the switchport trunk encapsulation command is not available then you don't need it This is what I and Jon are trying to tell you all the time. Your switch in this case supports only 802.1Q which is exactly the same encapsulation as used by the other switches, so your trunk should work just fine.

If you want to be absolutely sure about the capabilities of the particular port, try out the following command:

show interface X capabilities

Substitute X with the correct name/number. If the port supports only 802.1Q, you will get something like this:

FastEthernet0/1

Model: WS-C2950T-24

Type: 10/100BaseTX

Speed: 10,100,auto

Duplex: half,full,auto

UDLD: yes

Trunk encap. type: 802.1Q

Trunk mode: on,off,desirable,nonegotiate

[ ... cut ... ]

In this case, the switchport trunk encapsulation is not supported nor necessary.

If the port supports other VLAN tagging/encapsulating schemes, the output would be:

GigabitEthernet0/1

Model: WS-C3560G-48TS

Type: 10/100/1000BaseTX

Speed: 10,100,1000,auto

Duplex: half,full,auto

Trunk encap. type: 802.1Q,ISL

Trunk mode: on,off,desirable,nonegotiate

Check the capabilities of your port using this command.

Also, 4948 is different from 4948E, so don't expect the features from one being available on the other just because the name of the platform is similar.

Best regards,

Peter

tuhinbhowmick · ‎09-13-2012

Hi Peter,

I have got the interface capabilites information as suggested.

4948 :

SW3#sh interfaces g1/1 capabilities

GigabitEthernet1/1

Model: WS-C4948-RJ-45

Type: 10/100/1000-TX

Speed: 10,100,1000,auto

Duplex: half,full,auto

Auto-MDIX: no

Trunk encap. type: 802.1Q,ISL

Trunk mode: on,off,desirable,nonegotiate

Channel: yes

As this switch is capable of supporting both 802.1q and ISL, so we are getting the trunk encapsulation to choose bettween 802.1q and ISL.

4948e:

SW#sh int g1/1 capabi

GigabitEthernet1/1

Model: WS-C4948E-RJ-45

Type: 10/100/1000-TX

Speed: 10,100,1000,auto

Duplex: half,full,auto

Auto-MDIX: yes

Trunk encap. type: 802.1Q

Trunk mode: on,off,desirable,nonegotiate

Channel: yes

For this switch, it supports only 802.1q only and it is enabled bydefault, that is why we are not getting the "switch trunk encapsulation" option.

So, to make a port trunk on 4948e switch, the below command should be sufficient then. Kindly correct me if I am wrong.

Basically we want to made two switch port as a trunk port and put them under port channel group for uplink the same with our VSS switch.

SW#sh run int g1/31

Building configuration...

Current configuration : 60 bytes

!

interface GigabitEthernet1/31

switchport mode trunk

end

SW#

Regards,

Tuhin

Peter Paluch · ‎09-13-2012

Hello Tuhin,

So, to make a port trunk on 4948e switch, the below command should be sufficient then:

interface GigabitEthernet1/31

switchport mode trunk

end

Yes, this is a perfectly correct configuration of a trunk on ports that support only 802.1Q. I guess this solves your issue

Best regards,

Peter

tuhinbhowmick · ‎09-14-2012

Hi Peter,

Sorry for delaying reply.

Thnx for ur help and clarification.

Regards,

Tuhin