Problem with MST

[chitchat]

Sorry moi người vì mình post nguyên văn từ forum khác :

Hi all !

I have a problem with spanning tree in my network ! The network diagram in the attach file.



I've configured MST with 1 instance and Core1 is primary root and core 2 is the secondary.
at the first time MST is configured, it don't work until I reboot Core1 ( although I tested with 6 catalyst 4507R in the same diagram connection and configuration, it work well and no need to reboot )and Spanning tree not apply on the connection from Core2 to Core switch SideA. so I use 1 connection from Core1 to SideA at this time. ( I don't add the Core switch SideA in MST because the application in sideA cannot down at this time and I'm afraid the Core SideA must be restarted like Core1 )

when the network run with nearly 20 access switch module Cisco 3020 configured MST. It's ok and no problem. But when the number access switch increase to 40 and some of them use common spanning tree , the problem's issued.
problem : the network have no loop and MST, CST block port well. But some time some switch has log like this :
Mar 27 09:50:32: %C4K_EBM-4-HOSTFLAPPING: Host 00:1A:4B:E0:D3:34 in vlan 1 is flapping between port Te1/1 and port Gi7/13
and the application fail, the application in SideA is ok. I login switch and show spanning tree, It's no loop. When the application start again, it works ok but some o'clocks it's fail again !

My Core1 version is : Software (s72033_rp-ADVIPSERVICESK9_WAN-M), Version 12.2(18)SXF13, RELEASE SOFTWARE (fc1)

My Distribute Switch ( C5407R) is : Cisco IOS Software, Catalyst 4000 L3 Switch Software (cat4000-I9K91S-M), Version 12.2(25)EWA7, RELEASE SOFTWARE (fc1)

When MST up the core1 see the Distribute like a prestandard :
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Te2/2 Desg FWD 2000 128.130 P2p Pre-STD-Rx
Te2/3 Desg FWD 2000 128.131 P2p Pre-STD-Rx

and the Distribute see the core is standard:
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Te1/1 Root FWD 2000 128.1 P2p

Please help me to show the problem and how to fix it !
thanks so much !!!

[dangquangminh]

Lỗi trên nguyên nhân duy nhân là do bị spanning tree loop. Nguyên nhân gây ra loop thì cũng hơi nhiều. Do đó bạn chatchit cần kiểm tra lại các nguyên nhân như UDLD nếu có kết nối cáp quang, duplex mismatch nếu có gắn switch mới vào, gói tin bị lỗi nhiều...

Xem thêm cách khắc phục ở đây:

http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a00800951ac.shtml

[tranmyphuc]

Chào !!!

Vấn đề bạn gặp phải là : " một host address ( MAC address of computer) là source address ( source MAC) cho nhiều port (những cổng giao tiếp trên Switch) => xuất hiện SP loop
Error Message when the Host Address is a Source Address on Multiple Ports

Problem

The <tt>%C4K_EBM-4-HOSTFLAPPING:Host [mac-addr] in vlan [dec] is flapping between port [char] and port [char]</tt> error message appears.
This error message appears on the switch when the switch detects the specified host address as a source address on multiple ports.


Explanation The specified host is detected as a source address on multiple ports. Normally, a host is supposed to be learned on only one port. The most common cause of this condition is spanning tree loops. All traffic from the specified host is temporarily dropped. After 15 seconds, forwarding is
reenabled.



Recommended Action Make sure that spanning tree is enabled to prevent spanning tree loops. If you
have spanning tree disabled, make sure that you have no spanning tree loops in your network.

Cause

The issue can occur due to Spanning Tree Protocol (STP) loops in the network that cause packet drops from the specific host. In addition to packet drops, STP loops lead to several other symptoms, which are listed here:

• Loss of connectivity to, from, and through affected network regions.
• High link utilization (often 100 percent).
• High switch backplane utilization (compared to the baseline utilization).
• Syslog messages that indicate packet looping in the network (for example, HSRP duplicate IP address messages).
• Syslog messages that indicate constant address relearning or MAC address flapping messages.
• An increase in the number of output drops on many interfaces.

Note: One or more of these symptoms independently can indicate different issues (or no issue at all). However, when you observe many of these symptoms at the same time, you must check whether a forwarding loop has developed in the network.

Nếu vẫn chưa tìm ra lỗi bạn thử dùng lệnh : show tech-support
Tham khảo thêm tại đây : http://vnpro.org/forum/showthread.php?p=75674



Chúc bạn vui !!!