This article explains the default behavior on EX2300, EX3400, EX4600, QFX5k series devices w.r.t xSTP BPDU (Bridge Protocol Data Unit) flooding, and provides a workaround to prevent it.
In the above-mentioned products, the default behavior of a switch is to address incoming xSTP BPDUs in the following way (when xSTP is not configured).
When a switch receives an incoming xSTP BPDU, it is sent to the PFE host path where it is re-inserted over the VLAN. This, in turn, may affect the link bandwidth as XSTP BPDU is flooded.
In order to prevent this from happening,
no-mstp-flooding, no-vstp-flooding
and
no-stp-flooding
have been introduced. By enabling these knobs under "
switch-options
", the packets are dropped at the PFE host path and never flooded/re-injected to the VLANs.
CLI commands:
user@host# set switch-options no-mstp-flooding
user@host# set switch-options no-vstp-flooding
user@host# set switch-options no-stp-flooding
Notes:
- Please verify the version on which you are trying to run the command. All three knobs are available for use in 15.1X53-D56 and 17.3 release onwards.
no-mstp-flooding, no-vstp-flooding
and no-stp-flooding are
hidden knobs and do not auto-populate on pressing the Tab key or the Space bar. You will have to type the command completely.
- This is not advised to be added to the configuration when xSTP is running on the setup since it prevents flooding of BPDUs to the VLANs.