Difference between tag and untag in topology creation

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What is the Difference between tag and untag in topology creation..... Say suppose 6 topologies ( Bridge @ AP) with different vlans are created on same interface and that interface also has mgmt IP on it and will be the only interface used connected to lan(switch)...... will all 6 topolies be created as tagged or untagged.......
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Posted 3 years ago

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Bharathiraja, Suresh, Employee

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Hi Sai,

Each topology is identified with the vlan ID and each L2 port can have only one untagged topology.VLAN ID is used as a Controller wide identification of the topologies, however the VLAN ID is only used for tagged topologies.

Thanks,

Suresh.B
OK got it.......Then how to achieve the above situation.... One interface only will be used on controller connecting to core switch. I need to create 6 B@AP topologies.... and I should be able to manage the controller through network with an IP address.....
(Edited)
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Eric Jones

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You should be able to use the management IP as untagged and the create the other topologies as tagged using whichever vlans you need, assuming those vlans are tagged on the switch port that the controller is connecting to.
OK got it..... Correct me if I am wrong. A separate topology has to be created with IP address with mode as physical and will be untagged on the port. And rest of the L2 topologies (B@AP) will be on the same port as tagged.....and a static route has to be created to the management IP gateway....
(Edited)
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Eric Jones

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Yes, somewhere on the network there needs to be routes created so that the different vlans can communicate.
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Rahman Duran

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Also note that If you use B@AP topology you don't need to tag the vlans on your core switch which is connected to controller interface. But you need to tag that vlans on switch ports which the APs connected.
But how will multiple topologies pass on single interface of controller. If u say on core vlans will not be tagged , that means on controller port all topologies should be untagged...... am I right... can you pls explain in detail.... there is lot of confusion....
(Edited)
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Gareth Mitchell, Extreme Escalation Support Engineer

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B@AP means bridge at AP, this is exactly what happens, all the traffic is switched at layer 2 in the defined vlan, user data traffic is not tunnelled back to the controller, traffic egressing the AP will be placed into the defined vlan, after that it's up to the wired network to deliver the traffic to its destination and back (by conventional switch/route)  If you define egress traffic as tagged in the AP config, then the AP expects to receive matching traffic tagged.

If you want to tunnel traffic to the controller so that it arrives at a central point, then use a bridge at controller topology (B@AC) - with this topology type, you would need to tag vlan traffic to the controller but not at the AP.

In summary:

B@AP traffic doesn't need to arrive at the controller tagged or untagged but does need to be tagged/untagged at the AP.
B@AC traffic doesn't need to arrive at the AP tagged or untagged, but does need to arrive at the controller tagged/untagged.
Choice of tagged or untagged is up to you.  As previously stated only 1 vlan can be untagged.

Also note that you cannot add a L3 entity to a B@AP topology.  The l3 entity (if required) must live elsewhere in the wired world, it's external to the controller/AP.
please correct me, say if I create a topology with l3 ip address with mode "physical" with vlan 10 as untagged, port being say esa0, that L3 ip address will be used for management of controller from network...right?

now say i create 10 topologies (B@AP on the same port esa0) which are mapped to multiple WLAN Services mapping to different vlans, now here's the dilemma

-> Is defining the port as esa0 for the toplogies mandatory for B@AP or vlan id is enough?

-> can i use the same port esa0 for all the toplogies and will it  be tagged?

-> If it is tagged, then configuring the port on switch to which controller is connected as "untag" only for vlan 10 do the job as B@AP.
(Edited)
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Gareth Mitchell, Extreme Escalation Support Engineer

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please correct me, say if I create a topology with l3 ip address with mode "physical" with vlan 10 as untagged, port being say esa0, that L3 ip address will be used for management of controller from network...right?
Assuming the management radio button is selected for that topology, yes.

 Is defining the port as esa0 for the toplogies mandatory for B@AP or vlan id is enough?


In the topology definition for B@AP there is no interface to configure.

can i use the same port esa0 for all the toplogies and will it  be tagged?
If you're using B@AP then this is not required.

-> If it is tagged, then configuring the port on switch to which controller is connected as "untag" only for vlan 10 do the job as B@AP.
If your management vlan is 10 then this would be ok, assuming your AP's are registering to this interface also then you would need Management and AP Registration radio buttons checked.
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Sai Prasad Rao Rapolu

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OK ....... so what you'll be doing is create one physical topology (untag) with ip, 6 B@ AP toplogies for end users (tagged) . make sure the switch port connecting controller will have only one vlan(part of physical toplogy IP/subnet) as untag........ on switchport to which ap is connected: configure 2 vlans (ap vlan as untagged & user can as tagged (as defined B@AP topology).........
(Edited)