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571
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5
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STP question...

tonyp8581
Level 1
Level 1

Hi,

I have a simple setup that consists of Router A (model 1800) and 2 switches (model 2950).

Port 1 of switch A is connected on port 2 of Router A and Port 1 of switch B is connected on port 3

of Router A.  Also, port 49 of switch A is connected on port 49 of switch B.

I want to add a third switch but unfortunately I don't have the finance for a high end switch.  I'm thinking

of adding a low end switch (ex: linksys).  One link to switch A and another link to switch B for redundancy purpose.

I know the low end switch is not STP enabled, but can this type of setup create any loop issues ??

Thanks

1 Accepted Solution

Accepted Solutions

glen.grant
VIP Alumni
VIP Alumni

    You would have an inherent loop in your setup when you connect A to B switch and then hang the dumb switch between them .  As long as spanning tree is running on the 2950 it should take care of the loop and block one of the uplinks from the dumb switch I believe .Been a little while maybe someone can chime in whether the 2950's will talk spanning tree thru that dumb switch ,  brain cramp on this side .  :-)  Make sure you do not have portfast turned on for the ports going to that dumb switch . In that setup though if someone connects say 2 ports together  by accident on the dumb switch it will likely take down that portion of the network  with no spanning tree protection on that dumb switch.

View solution in original post

3 Replies 3

glen.grant
VIP Alumni
VIP Alumni

    You would have an inherent loop in your setup when you connect A to B switch and then hang the dumb switch between them .  As long as spanning tree is running on the 2950 it should take care of the loop and block one of the uplinks from the dumb switch I believe .Been a little while maybe someone can chime in whether the 2950's will talk spanning tree thru that dumb switch ,  brain cramp on this side .  :-)  Make sure you do not have portfast turned on for the ports going to that dumb switch . In that setup though if someone connects say 2 ports together  by accident on the dumb switch it will likely take down that portion of the network  with no spanning tree protection on that dumb switch.

tonyp8581
Level 1
Level 1

Hi Glen,

Thanks for your quick reply,

I should be good to go.  I'll make sure I have portfast disabled on switch A & B (uplink ports only).

Tony

Tony,

Check the LinkSys switch you are getting as some of them you can enable STP.

Glen, 5+ on the helpful information.

Mike

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