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Cisco Employee

"second-dot1q" missing on 1841 15.1M IOS?

Dear friends,

I have two 1841 routers running different IOS versions:

  • R1 running 15.0(1)M3 Advanced IP Services
  • R2 running 15.1(4)M2 Advanced IP Services

R1 supports the encapsulation dot1q second-dot1q on FastEthernet subinterfaces. Surprisingly, R2 with the newer IOS (of the same feature set) does not have the second-dot1q command option.

I've done my Feature Navigator homework but I did not see any significant differences between these two IOS versions that would explain why the second-dot1q command is not available on R2. Am I missing something? Has the syntax changed, or a different feature set is needed for 15.1M and higher to get the second-dot1q command back?

Thank you very much!

Best regards,

Peter

2 REPLIES
New Member

"second-dot1q" missing on 1841 15.1M IOS?

I think this may be something to do with the way that IOS is licensed now, my friend had a similar  problem with some switches and he had to buy additional license to use L2 Tunneling/QinQ functionality.

Cisco Employee

"second-dot1q" missing on 1841 15.1M IOS?

Hi Chris,

Thank you for your answer!

I would gladly agree if I used a platform with software license/feature activation. However, this is still a 1841 ISR G1 router that has no concept of feature activation. The IOS feature set should unconditionally determine the set of available features and commands.

I can understand that features are being moved between different IOS feature sets among major releases. But I see no indication in the Feature Navigator that any similar feature has actually been removed from 15.0M.

Best regards,

Peter

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