Sub-interface issues 7609

[gerren.cartwright]

Good day everyone,

Looking for some quick help. I inherited a 7609. Trying to configure a gigiethernet interface in to virtual sub-interfaces. See config below:

*******DOSN'T WORK*******

!

interface GigabitEthernet2/8.579

encapsulation dot1Q 579

ip address 1.1.1.1 255.255.255.0

!

********************************

*******WORKS*******

!

interface GigabitEthernet2/8

  ip address 1.1.1.1 255.255.255.0

!

*********************

[turnera]

Configure the subinterface from within the interface and see if that works for you.

Go into the GE2/8 interface and remove the IP address. Then enter/configure the GE2/8.579 interface from there.

[gerren.cartwright]

!

interface GigabitEthernet2/8

no ip address

!

interface GigabitEthernet2/8.579

encapsulation dot1Q 579

ip address 1.1.1.1 255.255.255.0

no snmp trap link-status

!

STILL DOES'NT WORK

[turnera]

It looks as though you can configure dot1q on a fe port but not a ge port. That may be why it won't work for you.

Usage Guidelines

This command first appeared in Cisco IOS Release 12.0(1)T.

IEEE 802.1Q encapsulation is configurable on Fast Ethernet interfaces.

Example

The following example encapsulates VLAN traffic using the IEEE 802.1Q protocol for VLAN 100:

interface fastethernet 4/1.100

  encapsulation dot1q 100

[Gregory Snipes]

The port needs to be at least 100Mbps. Trunking is not supported on 10Mbps interfaces.

You have to put that quote in context. When release 12.0(1)T came out Gigabit was barely a finalized standard and had not found it's way into many pieces of equipment.

[Reza Sharifi]

When you say it doesn't work you mean it doesn't take the command? What error message you get?

Sent from Cisco Technical Support iPhone App

[turnera]

Gerren,

Try this:

Do a "show port capabilities ge2/8". If dot1q is the only thing that shows up then it is there by default and you do not need to add the command.

[Gregory Snipes · Accepted solution]

Looks like it should be working. What are you connecting to the port? Could you send us the config from that?

[Marek1205]

encapsulaton needs to be enable  on physical inerface not on  sub as far as I know.

[gerren.cartwright]

Gregory you were right, the device that was connected was mis-configured. A bit of a language barrier between me and the other network admin.

[Marek1205]

Hi Garren,

Would you please give us more details about misconfiguration of the device connected to your 7609 ? How come is it working now ?