Disable Switch VLAN IGMP Snooping
IGMP snooping allows a switched network with multicast enabled to limit traffic to those switchports that have users who want multicast to be seen while pruning the multicast packets from switchports that do not wish to see the multicast stream. In a Vocera deployment, it can be undesirable to enable CGMP or IGMP snooping on the upstream switchport to the controller with software releases earlier than 4.0.206.0.
Roaming and multicast are not defined with a set of requirements to verify that multicast traffic can follow a subscribed user. Although the client badge is aware that it has roamed, it does not forward another IGMP join to make sure that the network infrastructure continues to deliver the multicast (Vocera broadcast) traffic to the badge. At the same time, the LWAPP access point does not send a general multicast query to the roamed client to prompt for this IGMP join. With a Layer 2 Vocera network design, disabling IGMP snooping allows traffic to be forwarded to all members of the Vocera network no matter where they roam. This ensures that the Vocera broadcast feature works irrespective of where the client roams. Disabling IGMP snooping globally is a very undesirable task. It is recommended that IGMP snooping only be disabled on the Vocera VLAN that is directly connected to each WLC.
Refer to Configuring IGMP Snooping for more information.
Router(config)#interface vlan 150
Router(config−if)#no ip igmp snooping
Multicast Enhancements in Version 4.0.206.0 and Later
With the release of 4.0.206.0, Cisco introduces an IGMP query to allow users to roam at Layer 2 by sending a general IGMP query when this occurs. The client then responds with the IGMP group that they are a member of and this is bridged to the wired network as described earlier in this document. When a client roams to a controller that does not have Layer 2 connectivity, or a Layer 3 roam, synchronous routing is added for multicast source packets. When a client, who has completed a Layer 3 roam sources a multicast packet from the wireless network, the foreign controller encapsulates this packet in the Ethernet over IP (EoIP) in IP tunnel to the anchor controller. The anchor controller then forwards that to the wireless clients locally associated as well as bridge this back to the wired network where it is routed using normal multicast routing methods.
Deployment Scenarios
These three deployment scenarios cover best practices and design parameters to help with a successful Vocera Badge deployment:
∙Single Controller Deployment
∙Multiple Controller Layer 2 Deployment
∙Multiple Controller Layer 3 Deployment
Understanding how the Vocera Badge features interact within an LWAPP split MAC environment is essential. With all deployment scenarios, multicast should be enabled and aggressive load balancing should be disabled. All badge WLANs should be contained within the same broadcast domain across your entire network.
Figure 4
