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What the difference when APs are connected to a Access port or a trunk port

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Feb 23rd, 2012
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Hi,

Just have a minor confusion today, what is the major difference when we have APs connected to the Access port of the Switch of when we have Trunk port connected to AP.

Well, I understand the difference between Access port and trunk but on trunk we can flow multiple vlan together.. but the similar way the AP broadcast multiple SSID at the sametime which are further mapped with multiple VLANs at the WLC.

Can we use trunk ports for the APs being used in local mode. And if we don't have Access port connected AP then how does the Voice packet travels when it comes out of the CAPWAP tunnel and moving toward the client ? Does it carry the QOS tagging done at the WLAN level ?

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Leo Laohoo Thu, 02/23/2012 - 19:29
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what is the major difference when we have APs connected to the Access port of the Switch of when we have Trunk port connected to AP.

Normally, if you have a WAP that's controller-based, the WAP goes into an access port.


Only autonomous WAPs that have multiple VLANs need to go into 802.1q Trunk port.  If you have an autonomous WAP and only has the default WAP then you can stick this into a access port.

chopra.harish1 Thu, 02/23/2012 - 21:31
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I aggree with your point Leo and I know that Controller based AP goes to the Access port only. But what about the multiple SSID they broadcast through one AP (which is connected to the Access port of the switch.).

Apart from that, how's the DSCP or QOS packets usually treated between WLC and AP both at Ingress and outgress ?

Leo Laohoo Thu, 02/23/2012 - 22:38
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But what about the multiple SSID they broadcast through one AP (which is connected to the Access port of the switch.).

Remember that the connection between the WLC and the LAN is a trunk port.  As to the WAPs, it's still an access port.

Darren Lynn Thu, 02/23/2012 - 20:34
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trunk ports can also be used in flex connect / hreap mode also


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Stephen Rodriguez Fri, 02/24/2012 - 04:48
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For the CAPWAP/LWAPP all the client traffic is tunnels back to the controller in local mode. Only in HREAP/FlexConnect does it hit the LAN from the AP directly.


That being said. A local mode AP only needs to be an access port but you could run it on a trunk port if you wanted to, so long as the correct native VLAN was set. But agin with local mode there is no reason to.


Steve


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Stephen Rodriguez Fri, 02/24/2012 - 04:48
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For the CAPWAP/LWAPP all the client traffic is tunnels back to the controller in local mode. Only in HREAP/FlexConnect does it hit the LAN from the AP directly.


That being said. A local mode AP only needs to be an access port but you could run it on a trunk port if you wanted to, so long as the correct native VLAN was set. But agin with local mode there is no reason to.


Steve


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chopra.harish1 Fri, 02/24/2012 - 22:49
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Hi Steve,

I guess I couldn't make my question much clear. Anyways, I read one Cisco Document last night and it answered my question that what happens to the Voice packet as it has to carry some DSCP/Cos Value with it and travel via a AP to the client and when the AP is connected to the Access port -

The answer is - When a Packet travels from Switchside to the WLC, if the Cos value defined in the packet is less than the Priority defined in the WLAN then it will accept the packet as it is and Forward it to the AP without making any changes... But if the pririoty defined in the packet is more than that defined in the WLAN at the WLC, the WLC will remark the packet with it's given priority and then forward the packet to the AP. The protocol used in this is called - 802.1P(Defined for Traffic clasification.)


Thanks for your help

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