Sections Included in this Document
vWLAN is user-based VLAN ready, which allows an administrator to shrink broadcast domains easily and to place users into the proper network or VLAN-based on credentials. vWLAN’s Layer 2 architecture allows multicast support without the need for protocol awareness such as Distance Vector Multicast Routing Protocol (DVMRP) or Protocol Independent Multicast (PIM) sparse mode (PIM-SM) when multicast is allowed in the AP firewall. This document covers how to enable Mutlicast on vWLAN 2.3 and later.
For the purpose of this document, a vWLAN appliance or Virtual Machine running vWLAN 220.127.116.11 or later is required. Further, Bluesocket Access Point (BSAP) firmware 6.7.0-23 is recommended for use with this version of vWLAN. You can find additional information under the vWLAN software notifications (https://supportforums.adtran.com/community/bluesocket/bluesocket-vwlan/software).
By default, "Convert Multicast to Unicast" is enabled on an SSID. Multicast transmissions are typically sent from one source to several destinations or to all destinations. From a security standpoint, it is difficult to configure the firewall properly for multicast transmissions between different client types because it is not client specific, but rather a multicast address. Converting multicast to unicast allows you to police traffic more efficiently because the traffic is split into individual streams destined to each client. In addition, when multicast and broadcast transmissions are sent wirelessly, they use the lowest data rate available, resulting in lower performance than unicast transmissions. If traffic is converted from multicast to unicast, it is sent using a higher data rate which improves performance, using less air time. Again unicast traffic is sent to a single client, therefore it can be sent at the speed of each client rather than that of the slowest client.
Anytime the AP is configured to edit or change traffic "Convert Multicast to Unicast", there will be an added overheard. In this case, the additional overhead is coming from the unicast acknowledgments, whereas with multicast/broadcast there are no acknowledgements. Converting multicast to unicast will add fidelity because of the acknowledgment, but that will also add another frame and if missed, will add re-transmissions which are more likely to occur on a WLAN compared to a wired network. Multicast does not possess the same fidelity as unicast because multicast traffic because clients must check in with the AP to receive buffered frames. The amount of time required to wake up the client can be edited using the Beacon intervals and DTIM values.
Adtran does not recommend converting multicast to unicast if there will be more than seven clients associated to each radio. If you do not choose to convert multicast network traffic to unicast traffic, you must allow multicast traffic in the role of the SSID. If you do not allow multicast traffic in the SSID’s role, and you do not choose to convert multicast traffic to unicast traffic in the SSID, then multicast traffic from a wired host or wireless client on another AP will not be seen.
By default, "Convert multicast to unicast" is enabled on the SSID. On a per-SSID basis, you can determine if the system should convert multicast and/or broadcast packets to unicast frames for wireless clients (this is already done for wired clients). Navigate to the Configuration tab, and select Wireless > SSIDs. Here any previously configured SSIDs are displayed, and the name, role, broadcast SSID, authentication method, accounting server, and cipher type for each SSID is displayed. You can edit an already configured SSID by selecting the SSID or by selecting the edit icon next to the SSID in the list. To create a new SSID, select Create SSID from the bottom of the menu or select Domain SSID from the Create drop-down menu (at the top of the user interface) as illustrated in Figure 1. Specify whether the SSID will convert multicast or broadcast network traffic to unicast traffic by selecting the appropriate option from the Convert drop-down menu. You can select to "Disable" to turn this feature off.
To allow multicast traffic in the Default Role of the SSID you will first need to create a destination and then assign that destination to the User's Role. By default, when a user connects for the first time and has not been authenticated, the user’s role is Un-registered.
To configure the destination, follow these steps:
Next, you will need to configure the role(s) accordingly. Roles are all configurable from the Configuration tab. To configure the domain roles, follow these steps:
If you are having issues with multicast after making the necessary changes to allow multicast, it is recommended to take an AP packet capture to confirm multicast is traversing the AP properly. For more on how to take an AP Packet Capture, please refer to the Bluesocket AP Traffic Capture Guide