Preview Tool

Cisco Bug: CSCun23612 - 7841 Cannot join VLAN if broadcast over 30kbps

Last Modified

Dec 13, 2019

Products (4)

  • Cisco IP Phone 7800 Series
  • Cisco IP Phone 7841
  • Cisco IP Phone 7821
  • Cisco IP Phone 7861

Known Affected Releases


Description (partial)

7841 Devices are not able to process CDP response to gain VLAN knowledge from switch when large amount of broadcasts (30kbps / approx 40 to 60 pps) on VLAN/Subnet are occurring. 

The phone looks like it will still follow through with DHCP requests but will not accept the offered DHCP address due to the phone not knowing the VLAN structure.

** Issue does not occur when same amount of traffic is sent directly to the phone; only when it is broadcast traffic.

7841 on a switch port with a VLAN with a large amount of broadcasts occurring in subnet.

Related Community Discussions

New 7821 DHCP Issues
We are trying the new 7821 and it won't pull an address from the dhcp server/router. It's set up as standard dhcp with option 150 for voice. Our 7962s receive an address right away, so the only difference one is using the skinny protocol and the other SIP. Should I be using a different option?
Latest activity: Nov 10, 2014
Bug details contain sensitive information and therefore require a account to be viewed.

Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
  • Severity
  • Known Fixed Releases
  • Related Community Discussions
  • Number of Related Support Cases
Bug information is viewable for customers and partners who have a service contract. Registered users can view up to 200 bugs per month without a service contract.