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3750 stackable switches

Hello,

I have two 3750 stackable switches, if one switch goes down, do the computers connected to that bad switch virtually connect to the network through the other switch, or do you need three 3750 stackable switches for this theory to take effect.  Also, if the master switch goes down can the computers connected to that

master switch connect to the network throught the other switch which is not the master switch?

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Participant

3750 stackable switches

If the switch goes down, the computers connected to are down. They do not connect through any other switch. Even if you have 3 switches with all the stack cables, still the PCs connected to the bad switch remain down.

Let's say that the PC that you are using has two NICs, one connects to switch1 in stack & other NIC connects to Switch2 in stack & Switch1 (non-master) goes down, the PC will still be able to communicate through one NIC. If it just has one NIC & its connected to bad switch, i cannot communicate in any scenario.

If master goes down, there is a re-election for master. Take a look at the following link for details:

http://www.cisco.com/en/US/products/hw/switches/ps5023/products_configuration_example09186a00807811ad.shtml#election

HTH,

Amit

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3750 stackable switches

So then what is the advantage of having stackable switches?

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3750 stackable switches

So if you have one NIC connected to one switch and another NIC to another switch and one switch goes down does the NIC card that was connected to the bad switch still have connectivity or only the NIC that was connected to the good switch have connectivity?

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Advisor

3750 stackable switches

  Lot of variables here . If a switch goes down then as others have said the pc's on that switch are down . How would they connect if that switch is faulty.  If you have dual nics connected to different switches it could failover  Stacking you can have a single ip management address to manage a stack of up to 9 connected switches.  Other caveats  if you only have a single uplink out of that stack and the switch with the uplink fails then you would not be ablle to get off that stack .  The switches that remained up , the clients might be able to talk between themselves if ip routing is turned on . in a dual nic setup only the nic on the good switch would have connectivity , once again how could the one nic talk if the one switch is faulty ? 

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Hall of Fame Community Legend

Re: 3750 stackable switches

I have two 3750 stackable switches, if ##one switch goes down, do the computers connected to that bad switch virtually connect to the network through the other switch,

Depends on how many NICs your computer has.  If, for example, your computer has two nics and each NIC is connected to each stack member then if one of the two goes down, the computer won't even notice this and continue to send/receive data.

Also, if the master switch goes down can the computers connected to that master switch connect to the network throught the other switch which is not the master switch?

Yes and No.  Yes if this computer's switch port configuration is the same as the others and with only one NIC per computer then you need human/manual intervention to move the NIC from the one switch member to another.

The scenario that I've mentioned above is mostly done in a server-like environment where each server, due to the importance of the said server and the amount of data it transfers, require more than one NIC and configured as NIC Teaming or EtherChannel.

In a hospital environment, what we've done is configure all ports to be the same.  Each computer is assigned TWO data outlets.  Each data outlet is patched.  One outlet goes to one 4500R+E chassis and the other data outlet goes to another.  In case either one chassis goes down, the users have been given explicit instructions to move the patching to the next data outlet.

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Re: 3750 stackable switches

So what are the main advantages of having stackable switches to non-stackable switches?

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Hall of Fame Community Legend

3750 stackable switches

It's simple:  Redundancy.  Redundancy when we are talking about two or more links to the client and redundancy when we talk about two or more links from the switch to the network.  If one of the switch stack member fails then your data will continue to flow from your PC's second nick to the remaining switch stack member and out to the rest of your network or internet.

Another advantage for stackable switches is the management of the switches.  Instead of logging into each switch you just configure each member of the switch on one switch.

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Re: 3750 stackable switches

If the port 2 on one of the stackable switch goes down does the server connected to that port that is down still have connectivity through other the stackable switches?

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