Why ASA 5520 has subinterfaces

[mahesh18]

             Hi all,

I am new to ASA  cisco 5520 firewall.

I checked config of ASA  5520 it has subinterfaces on gigabit.

Need to know why we create subinterfaces when it has already 4 lan interfaces?

Thanks

MAhesh    

[Kevin P Sheahan]

Subintefaces can be created for different VLANs that all come in on one physical port. Like 'Router on a Stick'.

Kind Regards,

Kevin

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[varrao · Accepted solution]

Apart from what Kevin said, they are also created if you need the other physical interfaces for some future purpose as well, or if the no. of interfaces that you need is greater than the no. of physical interfaces you have on the ASA.

Thanks,
Varun Rao
Security Team,
Cisco TAC

[mahesh18]

Hi Varun,

Thanks for reply.

so it means that ASA  also use same trunking protocol like 802.1q same like routers and switches?

MAhesh

[Kevin P Sheahan · Accepted solution]

Yes the ASA uses 802.1Q.

Sent from Cisco Technical Support iPhone App

[mahesh18]

Hi Kevin and Varun,

Many thanks for your replies.

As i am new to ASA and i have to work on it now as my new jon so will ask more questions

Regards

MAhesh