Preview Tool

Cisco Bug: CSCvu68537 - DHCP snooping is not processing some packets when span is enabled

Last Modified

Oct 06, 2020

Products (1)

  • Cisco Catalyst 3850 Series Switches

Known Affected Releases

16.12.3 16.9.5

Description (partial)

1. Unicast inform-ack packets are not processed nor forwarded by the switch when dhcp snooping is enabled.

2. The DHCP client obtains an IP address easily with no problems, but when it tries to get some new information using inform/ack procedure the switch will drop the ack packet.

3. Inform ack is not detected, but its seen using EPC.

1. Issue seen on C3850.
2. Software: IOS XE 16.9.5 and 16.12.3a.
3. DHCP snooping enabled.
4. DHCP client obtaining DHCP options (tested with option 120).
5. span session is configured on the TX direction interface
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.