Stp Interface Root-Protection - 3Com 7750 Series Command Reference Manual

3Com Switch 7750 Series
Command Reference Guide – MSTP

1.1.24 stp interface root-protection

Syntax
stp interface interface-list root-protection
undo stp interface interface-list root-protection
View
System view
Parameter
interface-list: Ethernet port list. You can specify multiple Ethernet ports by providing this
argument in the form of interface-list = { interface-type interface-number [ to
interface-type interface-number ] } &<1-10>, where &<1-10> means that you can
provide up to 10 port indexes/port index ranges for this argument.
Description
Use the stp interface root-protection command to enable the root protection function
on specified port(s).
Use the undo stp interface root-protection command to restore the root protection
function to the default state on specified port(s).
By default, the root protection function is disabled.
Configuration errors or attacks may result in configuration BPDUs with their priorities
higher than that of a root bridge, which causes new root bridge to be elected and
network topology jitter to occur. In this case, flows that should travel along high-speed
links may be led to low-speed links, and network congestion may occur.
You can avoid this by utilizing the root protection function. Ports with this function
enabled can only be kept as designated ports in all spanning tree instances. When a
port of this type receives configuration BPDUs with higher priorities, it changes to
Discarding state (rather than becomes a non-designated port) and stops forwarding
packets (as if it is disconnected from the link). It resumes the normal state if it does not
receive any configuration BPDUs with higher priorities for a specified period.
Related command: stp root-protection.
Caution:
Among loop prevention function, root protection function and edge port setting, only
one can be valid on a port at one time.
Chapter 1 MSTP Configuration Commands
1-26