VSP9000 v3.3.3.0 SNMP INFO Loop detected on port x/y vlan z, Mac addr Port is disabled

Doc ID    SOLN244833
Version:    1.0
Status:    Published
Published date:    13 Feb 2014
Author:   
Rimi Griyaghey
 

Details

customer sees MAC-FLAP in interface state output
logs also suggest mac flap but not the same mac address

Problem Clarification

VSP-BLA:1#show interfaces gigabitEthernet state 9/9

================================================================================
Port State
================================================================================
PORT NUM ADMINSTATUS PORTSTATE REASON DATE
--------------------------------------------------------------------------------
9/9 up down MAC-FLAP 02/01/14 20:40:20

SNMP INFO Loop detected on port 9/9 vlan 120, Mac addr 68:05:ca:16:e5:65. Port is disabled.
DYNAMIC NONE GlobalRouter SNMP INFO Vlacp link down(9/9)

Cause

In Release 3.3.0.0 a new feature was enabled by default to protect a newly booted box from
existing network loops. The feature enables MAC-FLAP loop detect on ports without
any MAC-FLAP protection configured and will shutdown a port at least 10 seconds
after it has detected excessive MAC flapping. Within the first 10 seconds it will detect movement, then the second 10 seconds will count and shutdown the port when the count reaches 100. That means the real shutdown time is 10 s < shutdown time <= 20s.

MAC-FLAP feature works when VSP sees one mac address on different port many times.

To check mac flapping, colect below command outputs

show vlan mac-address-entry mac 68:05:ca:16:e5:65 port 9/9
sho ip interface
sho ip arp

Solution

If SLPP is enabled on the SMLT Cluster core,
SLPP Guard should also be enabled on all access ports switch on Edge Switch. When
operational, SLPP-guard will immediately administratively disable a port when a SLPP
packet is received on a port and generate a local log message, syslog message (if
the syslog server(s) are configured) and SNMP traps (if SNMP tap receivers are
configured).

 


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