Loop Guard; Root Guard; Igmp Snooping - Mellanox Technologies Mellanox SX1018 User Manual

BPDU filtering is configured per interface. When configured, the port does not send any BPDUs
and drops all BPDUs that it receives. To configure BPDU filter, use the following command:
switch (config interface etherent <inf>)# spanning-tree bpdufilter {enable , disable}
Configuring BPDU filtering on a port connected to a switch can cause bridging loops
because the port filters any BPDU it receives and goes to forwarding state.
5.5.4

Loop Guard

Loop guard is a feature that prevents loops in the network.
When a blocking port in a redundant topology transitions to the forwarding state (accidentally),
an STP loop occurs. This happens when BPDUs are no longer received by one of the ports in a
physically redundant topology.
Loop guard is useful in switched networks where devices are connected point-to-point. A desig-
nated bridge cannot disappear unless it sends an inferior BPDU or brings the link down on a
point-to-point connection.
The loop guard configuration is only allowed on "network" port type.
If loop guard is enabled and the port does not receive BPDUs, the port is put into an inconsistent
state (blocking) until the port starts to receive BPDUs again. A port in the inconsistent state does
not transmit BPDUs. If BPDUs are received again, loop guard alters its inconsistent state condi-
tion. STP converges to a stable topology without the failed link or bridge after loop guard isolates
the failure.
Disabling loop guard moves all loop-inconsistent ports to listening state.
To configure loop guard use the following command:
switch (config interface etherent <inf>)# spanning-tree guard loop
5.5.5

Root Guard

Configuring root guard on a port prevents that port from becoming a root port. A port put in root-
inconsistent (blocked) state if an STP convergence is triggered by a BPDU that makes that port a
root port. The port is unblocked after the port stops sending BPDUs.
To configure loop guard use the following command:
switch (config interface etherent <inf>)# spanning-tree guard root
5.6

IGMP Snooping

The Internet Group Multicast Protocol (IGMP) is a communications protocol used by hosts and
adjacent routers on IP networks to establish multicast group memberships. The host joins a mul-
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