Network diagrams help in understanding topology and concern. So if a L2 VLAN is extending a VPN link, you are worried about inter IAP communication, saturating it.
Only management plane is centralized. Control and data plane are distributed. management plane constitutes of Configuration, monitoring, firmware upgrades. So if you are not pushing expensive upgrades too often, i would still say the inter IAP traffic would be less than more prevalent L2 traffic e.g. ARP.
You can put two IAP in a cluster and find out how much of traffic is inter IAP in a normal usage scenario.
I am taking a snippet from VRD to show how inter IAP communication looks like.
chapter 1 instant communicatoins
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There are two major types of communication between APs in a cluster:
- L2 Broadcast messages for cluster maintenance and roaming
Master AP sends out a Layer 2 “beacon” message every second to notify that the master AP is currently active. This helps in new APs discovering the master and join the cluster & existing APs detecting master failover and take over as master of cluster.
There is also a session request message for Layer 2 roaming. When a client roams between APs in a cluster, a session request message is used to transfer client session and role data between APs
Sample frame for L2 communication:
- L3 unicast messages between IAPs (master and slave)
UDP messages on port 8211 between master and slave APs for config sync, firmware upgrade and control-plane messaging between APs.
Sample frame for L3 unicast communication: