I have a 3750 Cisco switch. I connected it to a bunch of Onenet switches that are in a daisy-chain topology.
Since I don't have management over the Onenet switches, the 3750 interface - that connects to Onenet- is put in vlan access mode:
3750Sw#sh run int fa1/0/48
Current configuration : 232 bytes
description --- uplink access vers Onenet switches ---
switchport access vlan 1100
switchport mode access
mls qos trust cos
spanning-tree bpdufilter enable
The reason behind "no keepalive" is that the 3750 keeps on sending keepalives and does not receive any from Onenet. This leads to a "loop" syslog message and the port is err-disabled.
What are the drawbacks of this design? Is there any better?
Solved! Go to Solution.
A loopback error occurs when the keepalive packet is looped back to the port that sent the keepalive. The switch sends keepalives out all the interfaces by default. A device can loop the packets back to the source interface, which usually occurs because there is a logical loop in the network that the spanning tree has not blocked. The source interface receives the keepalive packet that it sent out, and the switch disables the interface (errdisable). This message occurs because the keepalive packet is looped back to the port that sent the keepalive:
%PM-4-ERR_DISABLE: loopback error detected on Gi4/1, putting Gi4/1 in err-disable state
Keepalives are sent on all interfaces by default in Cisco IOS Software Release 12.1EA-based software. In Cisco IOS Software Release 12.2SE-based software and later, keepalives are not sent by default on fiber and uplink interfaces. For more information, refer to Cisco bug ID CSCea46385 (registered customers only) .
The suggested workaround is to disable keepalives and upgrade to Cisco IOS Software Release 12.2SE or later.
But it might be an idea to make sure you don't have any loops in the network. Maybe in those onenet switches there are two cables between a couple of switches, or they don't support SPT?? or something. Would be a good idea to check that. What you have done is apply a workaround, which is fine, but it would be good to find the route cause and resolve that.
Our 3750 IOS version is 12.2(50)SE1. Yet it sends keepalives.
Maybe in those onenet switches there are two cables between a couple of switches, or they don't support SPT??
Are there switches that do not support STP? I thought that all switches out in the market do support it.
We don't have support over the Onenet switches. They're black boxes for us