======Support for IGMP at layer 2======


**Symptoms:** 
  * Enable time updates, paging, conferencing, etc.  
  * Support for IGMP at layer 2  
  * After initial download and re-boot, phones no longer talk to the NCP   
  * Phones can not find the NCP or bootup completely  
  * Phones will not Auto-Discover  
  * Status shows unknown  
  * Paging not working  
  * Conferencing not working  
  * Time incorrect  
  * Date incorrect  
 



 
**Facts:**
  * SuperStack 3 NBX  
  * NBX 100  
  * NBX 25  
  * SuperStack 3 Switch 4900  
  * NBX Phones  
  * NBX Cards and Adapters  
  * NBX Call Processor  
  * IP Multicast  
  * IP  
  * IGMP Snooping  




**Causes:** NBX phones do not send out join requests for multicast groups used for communications such as paging, conferencing, and getting date and time information. The phone does send out multicast packets that are needed to communicate with the NCP at a layer 2 level, and the NCP does likewise when it needs to send information via multicast packets at layer 2. Prior to R4_0_2 these packets are sent out as an IP Multicast packet even though the communication is at a layer 2 level. This means that some switches (3Com SuperStack 3 4900 for example) have filtering on by default and therefore do not forward these packets. The NBX Phones SUPPORT IGMP version 2 at layer 3.  
 




**Fixes:** Upgrade to R4_0_2 or higher. This is not supported on the NBX 25.  
Work-around: Disable IGMP Snooping on all the switches between the phones and the NCP  



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  * Product(s):  NBX, SuperStack 3 Switches  
  * Sub Product(s): NBX 25, NBX 100, NBX Call Processor, NBX Phones, SuperStack 3 Switch 4900, SuperStack 3 NBX  
 





 --- //[[nce@itclatam.com|David Gonzalez]] 2021/04/12 10:50//