Compare Dot1Q and QinQ with Access and Trunk ports?

[msgforsunil]

Hello All,

How do you compare Dot1Q and QinQ with Access and Trunk ports?

Thanks

Sunil Kumar

[Rajeev Sharma]

Hey Sunil,

With Dot1q links both sides are configured as trunk links however with QinQ we configure asymmetric link, i.e. one side is trunk and other is access.

HTH.

Regards,

RS.

[msgforsunil]

Thanks Michael and Rajeev.

Rajeev, I think, you meant the below right?

1. Dot1Q(Trunk) ---Dot1Q(Trunk)

Wont we have a case of Dot1Q configured on Access port?  If no, then why?

2. How would the topology be for QinQ case?

QinQ(Trunk)---QinQ(Access)?

Kindly clarify.

Thanks in advance!

Sunil Kumar

[Rajeev Sharma · Accepted solution]

Hey Sunil,

Regarding your questions:

1. Wont we have a case of Dot1Q configured on Access port?  If no, then why? - The purpose of dot1q is to tag the frames leaving the switch and the access is opposite, it doesn't perform tagging hence not used together.

2. How would the topology be for QinQ case? - For QinQ as I mentioned in my last post one side will be configured for trunking while other for access. A simple example is explained on this link:http://networklessons.com/switching/802-1q-tunneling-q-q-configuration-example/

HTH.

Regards,

RS.

[msgforsunil]

Thanks a lot, Rajeev for the clarification.

[michael o'nan]

Dot1Q is the IEEE standard for tagging ethernet frames. You would typically configure and 802.1Q (Dot1Q) trunk to pass your tagged VLANs. Cisco offers and alternative called ISL trunking. A trunk is typically used to connect switches together. This allows them to pass tagged traffic and it stay "separated" until reaching its L2 or routing destination.

QinQ is seen mostly with service providers. This enables multiple VLAN tags to be inserted into a single frame. This allows SP to offer a layer 2 network to customers and support the customer VLANs. This is mostly seen in MetroE topologies.

An access port is a port that is statically configured to a VLAN. Any traffic it receives gets marked to the VLAN set on the port and any traffic sent out that port has no VLAN tag. This is typically used on PCs or other end user devices.