Notice Summary
An issue has been identified where a loop occurs in EAPS and STP environments running EXOS/Switch Engine 32.2 when using flood to VLAN filters for mDNS, LLMNR, and UPnP protocols.
Background
- Version 32.2 introduces support for flood to VLAN filters for mDNS, LLMNR, and UPnP protocols.
- This feature enables you to create filters that forward these three protocol packets to VLAN(s).
- Default setting for this feature is to "flood" (options are flood or learn) and this setting installs a port-based filter (i.e. match-condition “InPorts”) with action-item “redirect-vlan” in the hardware.
- This applies to both standalone switches and stacks.
- There is a defect which causes multicast traffic (mDNS, LLMNR, UPnP) to be looped when using this new feature in 32.2 in EAPS rings or STP domains.
Impact
Multicast traffic is not blocking by EAPS or STP, thus causing a network loop and potential network outage.
Products Affected
X435
X440-G2
X450-G2
X460-G2
X465
X590
X620
X695
5320
5420
5520
5720
Software Affected
EXOS/Switch Engine 32.2
Symptoms
- Network loop with high multicast traffic on VLANs and switch ports where mDNS, LLMNR, or UPnP flooding is enabled.
- EAPS and STP are forwarding (flooding) instead of filtering these three protocols on the EAPS/STP blocked ports as they normally do for data traffic to prevent loops.
Workaround
Run the following workaround command:
conf forwarding ipmc all learn
Solution
Upgrade to version 32.3 which has the solution for this software defect
Please see the full article here for more details.
