Netgear Switches GS748Tv4 and v5 ports go down and up and Spanning Tree Topology Change

by

I’m getting notifications on my Syslog server from the Netgear switches GS748Tv4 and v5. These are the notifications:

traputil.c(696) 122305 %% Link Down: g30                                
traputil.c(696) 122323 %% Link Up: g30
traputil.c(739) 122307 %% Spanning Tree Topology Change: 0, Unit: 1
traputil.c(739) 122308 %% Spanning Tree Topology Change Initiated: 0, Interface: g30

Not only for the port g30 but for other ports as well. STP is enabled on both swithces. I don’t know exactly what is causing this but when this happens, the user loses connection.

Any ideas?

Thank you,

Answer

Most likely, your category 6 wiring was done incorrectly. Carefully check the mapping of pins to wire pairs. I’ll bet that it will not conform to either 568A or 568B. This is essential for Gigabit Ethernet to work correctly.

The preferred mapping is:

  1. Orange/White
  2. Orange
  3. Green/White
  4. Blue
  5. Blue/White
  6. Green
  7. White/Brown
  8. Brown

Also acceptable is:

  1. Green/White
  2. Green
  3. Orange/White
  4. Blue
  5. Blue/White
  6. Orange
  7. Brown/White
  8. Brown

The wiring should be the same at both ends of each cable. If this is not how the cables are wired, this is almost certainly your problem. If this mapping is incorrect, the twists in the cable will be unable to serve their function of preventing the four differential signals from interfering with each other.

Attribution
Source : Link , Question Author : Blake Zero , Answer Author : David Schwartz

Leave a Comment