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Why using CE-VLAN ID Preservation matters in Carrier Ethernet?

Ideally VLAN ID Preservation should be preserved ( CE-VLAN ID = Yes). After all, why it should matter, changing VLAN IDs. Having same VLANs IDs make it operationally efficient for both operator and customer. Operator can trace the circuit well, so can the end customer by just knowing the VLAN IDs. Not to forget that it would be easy to setup such an EVC  since the VLAN ID to EVC map will be much simple in this case.

In this post I will explain that why it is needed to set VLAN Preservation ID = NO

Let’s see the example of setting VLAN Preservation ID = YES and its advantages. See the diagram 1 below, customer has two campuses with the same VLAN number 14. Obviously this situation demands that VLAN Preservation ID should be set to YES. Why asking the end customer to change VLAN IDs in the first place ?

Lets see a second scenario in which two campuses of the same customer are connected to each other but both have different VLANs. The obvious advantage here for using VLAN Preservation ID= No is to let the service provider do the switch and hence in that case the service provider will switch the VLAN ID from 15 to 14  before handing the traffic to B while the converse will be true when handing the traffic to A. This is shown in diagram 2 below.

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ipjunkie
ipjunkie
6 years ago

Hello
Thank you for your post. In order to understand it better I have a questions in my mind. In the second scenario where the site A and site B are using different vlans why the service provider is required to do the switch. If the SP preserve the CE-VLAN IDs, communication between the two sites would still be possible as I believe the EVC would function like a layer 2 Trunk.

But yes if you set the bundling to Disabled or No and you want to realize the scenario B without asking the customer to renumber its VLANs, yes in that case the translation would be required but the question is why would you set the Bundling to No or Disabled when the requirements doesn’t demand so.

So I would really appreciate if someone can put a more realistic real network example that would demand a CE-VLAN ID preservation = No

ipjunkie
ipjunkie
6 years ago

Hello Faisal, thanks alot for your kind input. But in that case all the traffic from one vlan will be handed over to the other vlan which is a rare sight in data networks , as normally we would have occasional requirements for inter-vlan communication.

With the scenario presented above for CE-VLAN preservation= no , how would the inter and intra vlan communication occur between two vlans simultaneously?
Say for example on site A &B we have multiple vlans including 15 and 14. There is an instance where a user on site A on vlan 15 would like to communicate with someone in Vlan 14 on site B, while other users from the same vlan would like to carry on with intra vlan communication on vlan 15. With the translation on, how would this kind of communication be possible?

ipjunkie
ipjunkie
6 years ago

Thank you Faisal. I really appreciate. It really helped.

ipjunkie
ipjunkie
6 years ago

in lieu of the discussion above it makes a perfect sense based on the simpl rules of address learning provided you have vlan 14 on one side and vlan 15 on other. But what if let’s say you have the both the vlans configured on both the switches i.e. vlans 14 and 15 on both switches at site A and site B. And lets say a user in vlan 14 on site A wants to communicate a user on vlan 14 on site B, in that case I guess it won’t work due to the translation as it would never be delivered to the correct vlan on site B.

trackback

Service Management – VLAN ID Preservation

Requirements Service Management functionality was

Azhar
Azhar
4 years ago

Very good explaination.

First case is an applicable when more than ONE CE-VLAN IDs are mapped to an EVC (Either Bundling or All-to-One-Bundling =Yes). You must preserve it in that situation.

When exactly ONE CE-VLAN ID is mapped to an EVC (Bundling=No and All-to-One-Bundling =No) , you have choice either to preserve it or translate it.

Azhar
Azhar
4 years ago
Reply to  Azhar

Only ONE translation per EVC is allowed.

Mohsen
Mohsen
8 months ago

Thank you very much. so helpful.
I have a question about the 802.1ad standard.
I have seen 3 types of interfaces. provider-network, customer-network, and customer-edge ports.
My problem is with this customer edge port. should it be similar to the dot1q port on the customer side? for example a customer edge-hybrid port should act as a hybrid port on customer side?

Mohsen
Mohsen
7 months ago
Reply to  Faisal Khan

Hi Faisal,
I mean I’ve seen some kind of QinQ configuration which it’s literature isn’t dot1ad standard. for example, an interface could be configured as switchport [provider-network | customer-network | customer-edge (access | hybrid | trunk)] but I’m not sure about their functionalities especially customer edge ports. I think these types of ports are equivalent to nni and uni -c/s ports in dot1ad standard. now my question is about customer-edge ports on the customer side( I think they are similar to uni-c ports in dot1ad). Should they act as normal access, trunk, or hybrid ports there?

Thank’s for your help

Mohsen

Mohsen
Mohsen
7 months ago

Hi Faisal,
I mean I’ve seen some kind of QinQ configuration which it’s literature isn’t dot1ad standard. for example, an interface could be configured as switchport [provider-network | customer-network | customer-edge (access | hybrid | trunk)] but I’m not sure about their functionalities especially customer edge ports. I think these types of ports are equivalent to nni and uni -c/s ports in dot1ad standard. now my question is about customer-edge ports on the customer side( I think they are similar to uni-c ports in dot1ad). Should they act as normal access, trunk, or hybrid ports there?

Thank’s for your help

Mohsen

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