We have three 24 port (Gigabit) Netgear GS724T switches which are connected in the following way:

SW-003 > SW-001
       > SW-002

The port on SW-002 that connects to Sw-003 is constantly flashing once per second, the rest are flickering as the data is transferring as expected.

I am concerned that this may mean that we are at risk of exceeding the Gigabit bandwidth between the two switches. If this is the case then I would presume the fix would be to enable a spanning tree - which I have tried but I can't understand if I need to enable a spanning tree with matching ports on all of the switches. So ports 1 and 2 on SW-002 has a spanning tree and ports 1 and 2 on SW-003 has a spanning tree enabled.

Is that correct?

At the moment I have connected an extra patch cable between the two and it seems to create some form of routing loop that causes all ports to flash once per second and the network stops working.

The monitoring results for the port is as follows:

Port Role Disabled
STP State Manual Forwarding
Admin Mode Enable
LACP Mode Enable
Physical Mode Auto
Physical Status 1000 Mbps Full Duplex
Packets RX and TX 64 Octets 323001614 
Packets RX and TX 65-127 Octets 19692371 
Packets RX and TX 128-255 Octets 8970100 
Packets RX and TX 256-511 Octets 8629484 
Packets RX and TX 512-1023 Octets 130326 
Packets RX and TX 1024-1518 Octets 2792337 
Packets RX and TX > 1522 Octets 0 
Octets Received 14989599039 
Packets Received 64 Octets 153708043 
Packets Received 65-127 Octets 11096781 
Packets Received 128-255 Octets 5619084 
Packets Received 256-511 Octets 4740987 
Packets Received 512-1023 Octets 85517 
Packets Received 1024-1518 Octets 1114750 
Packets Received > 1522 Octets 0 
Total Packets Received Without Errors 176365237 
Unicast Packets Received 55672181 
Multicast Packets Received 2910638 
Broadcast Packets Received 117782418 
Total Packets Received with MAC Errors 0 
Jabbers Received 0 
Fragments Received 0 
Undersize Received 0 
Alignment Errors 0 
Rx FCS Errors 0 
Overruns 0 
802.3x Pause Frames Received 0 
Broadcast Storm Recovery 0 
Total Packets Transmitted (Octets) 15915167667 
Packets Transmitted 64 Octets 169293572 
Packets Transmitted 65-127 Octets 8595590 
Packets Transmitted 128-255 Octets 3351016 
Packets Transmitted 256-511 Octets 3888570 
Packets Transmitted 512-1023 Octets 44809 
Packets Transmitted 1024-1518 Octets 1677587 
Packets Transmitted > 1522 Octets 0 
Maximum Frame Size 1518 
Total Packets Transmitted Successfully 186851144 
Unicast Packets Transmitted 58640169 
Multicast Packets Transmitted 5186416 
Broadcast Packets Transmitted 123024559 
Total Transmit Errors 0 
Tx FCS Errors 0 
Underrun Errors 0 
Total Transmit Packets Discarded 0 
Single Collision Frames 0 
Multiple Collision Frames 0 
Excessive Collision Frames 0 
Port Membership Discards 0 
STP BPDUs Received 0 
STP BPDUs Transmitted 0 
RSTP BPDUs Received 0 
RSTP BPDUs Transmitted 0 
MSTP BPDUs Received 0 
MSTP BPDUs Transmitted 56 
802.3x Pause Frames Transmitted 0 
EAPOL Frames Received 0 
EAPOL Frames Transmitted 0 
Time Since Counters Last Cleared   

Any advice would be appreciated.


Don't know what the flashing means, check your manual or call Netgear for that but it won't be to show you you're overusing the link - they're designed to sit there all day at 100% so don't worry about that. That said if you want more than 1Gbps of bandwidth it's not spanning tree you want but 802.3ad/LACP, which those switches support - two or more links bound together to act as one basically.

| improve this answer | |
  • I'm struggling to determine what the flashing means, I'm assuming it's a negative thing! I have got the manual in PDF format so I'll have a flick through now and read up on the LACP configuration etc. Thanks. – dannymcc Dec 5 '11 at 16:36
  • Call Netgear or look on their site. – Chopper3 Dec 5 '11 at 17:23
  • Will do, I have now configured the LACP settings. Thanks! – dannymcc Dec 5 '11 at 17:25

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