How do i setup a 3500XL to support teamed nics?

[chicocouk]

Ok, it's been forever since I did any switch configuration. But we have two 3548XL switches, running IOS 12.0(5). We have a load of new servers, with two nics in each, and those nics are teamed to share an ip address.

Currently one nic from each server is plugged into one switch, and the other is plugged into the equivalent port on the other switch. So server one has it's first teamed nic plugged into port 3 on switch one, and it's second teamed nic plugged into port 3 on switch two. All locked to speed and duplex, with portfast on.

I know that if both nics went into the same switch I can configure the two ports into an etherchannel using "port group 3". My question is this - does the etherchannel work across switches?

If I configure port 3 on switch one in port group 3, and port 3 on switch two in port group 3, will those two ports then be treated as an Etherchannel?

If i'm on the wrong lines with this, please let me know, it's been a long time since I did this stuff ....

Thanks

 

[vipergg]

No you cannot do an etherchannel like that . Only on newer switches like the 3750 that are stacked can you do what is called a cross stack etherchannel , those old 3500's will not support something like that. Also if they plugged into different switches are both those switches in the same subnet , if not you are going to have problems .

 

[chicocouk]

In the same subnet? In what sense? They're uplinked through gig ethernet through a core switch, they're not directly cabled to each other in any way.

So what's the recommended way to connect teamed nics on servers then? Both nics go into the same switch and etherchannel? That gives you a single point of failure obviously, if that switch goes.

Is there no way to have one nic in each switch with this hardware?

 

[KiscoKid]

Correct there is no way to connect one nic in each switch with your kind of switch. You are pretty much limited to all nic connections terminating on the same switch.

Cisco introduced the ability to split etherchannel across the stack with their new Stackwise switches, like the 3750. You can achieve what you want with a pair of these devices.

http://cisco.com/univercd/cc/td/doc/product/lan/cat3750/12119ea1/3750scg/swethchl.htm

 

[chicocouk]

Ok, thanks for the info. Without meaning to flog a dead horse does that mean there is no way to configure this to provide any kind of switch redundancy? If one switch goes down i'm basically going to lose all the servers hanging off that switch?

Thanks again for the help.

 

[chipk]

Try leaving out the etherchannel and nic teaming and just set up both nics on the network with two separate addresses. Provide your load-balancing through round-robin dns or some other method. Provides redundancy AND load-balancing. Unless a nic or switch dies, and then your users get a 50/50 chance of hitting the server. Of course, if you were pretty handy with dns you could script something to comment out whatever entry is bad if one of the switches/nics goes down.

 

[ADB100]

If you just want redundancy for the Server and no load-balancing then you can configure the NIC teaming for failover, whereby you have an Active/Standby configuration. This will work in the scenario you describe across 2 switches.

You would need to configure the NIC teaming for Network Fault Tolerant mode (NFT). Depending on your server or NIC's there should be a control panel applet that allows you to configure this.

HTH

Andy