06-12-2006 06:50 AM - edited 03-03-2019 03:36 AM
Hello
I have two 3560's that I have to monitor but wont physically be on my network. I vlan'd these switches so that one port would be seperated strictly so I could uplink them with my physical network for SMTP and monitoring.
My question is what port settings are best for this one port that goes back to my network? I would assume that technically being a trunk the port should be switchport mode trunk? and not access.
Funny thing is that when I set it as trunk and plug it in i see a topo change propogate out. Whereas when its set for switchport mode access I do not. STP is running in PVST
port stats are as follows
switchport access vlan 2
switchport trunk encapsulation dot1q
switchport mode trunk
spanning-tree portfast
i'm confused as to why this mode would cause the topo changes.
thanks
Eric
Solved! Go to Solution.
06-12-2006 06:57 AM
you will see a topo change when you set this port to a trunk as STP must assure a loopfree topology.
(a trunk acts like an extension of the bridge, ie: topo change when changing trunk operational status)
if the port is simply set to access w/portFast you will not see STP topo change.
also note, that this link only needs to be a trunk if it needs to support multiple VLANs. if there is only one VLAN on your LAN/switches, then a trunk is unecessesary.
it sounds like you could/want to set this up as only a routed interface uplink to the network, not necessarily a switched uplink to the network.
06-12-2006 06:57 AM
you will see a topo change when you set this port to a trunk as STP must assure a loopfree topology.
(a trunk acts like an extension of the bridge, ie: topo change when changing trunk operational status)
if the port is simply set to access w/portFast you will not see STP topo change.
also note, that this link only needs to be a trunk if it needs to support multiple VLANs. if there is only one VLAN on your LAN/switches, then a trunk is unecessesary.
it sounds like you could/want to set this up as only a routed interface uplink to the network, not necessarily a switched uplink to the network.
06-19-2006 11:48 PM
Hi,
you have configured a port to access vlan2. Also the same port as trunk port.
Note:Trunk ports are supposed to carry all VLans but not a single vlan.
If you using only a single vlan means trunk port can be used to connect between a switch & a router. In that case you can use switch's uplink port as the trunk port.
eg: int faeth 0/24
switchport trunk encapsulation dot1q
switchport mode trunk
spanning-tree portfast
Also in router the same:
#encapsulation dot1q
Portfast: If a port with portfast enabled means you should connect a device into it eg:switch/router/bridge but not a system becoz port with portfast enabled will make the port to comeup immediately even if goesdown ie., it skips the initial/listen state during the process and directly comes to forwarding state.
If a system is connected to a port with portfast enabled means STP loop may form and network congestion may occur.
Hope this will help you a lot!!!!
Plz rate if this help you!!!!
Regards,
Guru Prasad.R
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