Can you stack a Cisco 3560G ?

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cyr0n_k0r

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I can't seem to find any definitive answer to this question. You can buy stacking cables for the unit, but no where can I see where cisco says that the switches actually can be stacked. Other places I have read say you can't stack them, only cluster them.

Is this true? What is the difference between stacking and clustering?

I need the ability to run etherchannels across multiple switches so I can have redundant links on both switches. I would team NIC's on the other side so I could survive a link failure or a switch failure.

The model I am looking to buy are (2) WS-C3560G-48TS-S with (2) CAB-SFP-50CM Interconnect cables (to allow for 2Gb/sec throughput between switches)
 
3560s don't support StackWise, you'll need 3750s. You could run some channels for throughput, you'll lose the ability to manage the group as one logical switch though.
 
http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps5528/prod_qas09186a00801f3d71.html

Q. Can the Cisco Catalyst 3560 Series support Cisco GigaStack® or Cisco StackWise technology?
A. The Cisco Catalyst 3560 Series does not support Cisco GigaStack technology (available on the Cisco Catalyst 3550, 2950G, and 3500 XLs) or Cisco StackWise technology (available on the Cisco Catalyst 3750 Series). However, a cluster of any combination of these platforms can be managed over a single IP address using the Cisco Network Assistant software. There are more details on Cisco Network Assistant later in this document.
 
But what is the difference feature wise between a stack and a cluster?

So if I have a 4 port NIC team (3 active 1 standby ) with 2 running into switch 1, the other 2 running into switch 2 and they are etherchannels can this work with the switches being clustered? Or do they need to be stacked?
 
cyr0n_k0r said:
But what is the difference feature wise between a stack and a cluster?

So if I have a 4 port NIC team (3 active 1 standby ) with 2 running into switch 1, the other 2 running into switch 2 and they are etherchannels can this work with the switches being clustered? Or do they need to be stacked?
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No, it will not work. What you are looking for is cross-stack etherchannels, which is supported on the later 3750. You need the devices to be stacked and not just clustered.

If you decide to go with higher end switches you will see the technology called something differently, 6500 in VSS calls it Multichassis etherchannel,

Clustered for the 3560 simply means they(a cluster of switches) can be managed from ONE switch in the group. Stacking is creating one logical switch between two switching engines utilizing a high-speed fabric interconnect(for the 3750, its the stacker port, 32Gbps bi-directional). The data plane for each switch is functional and operates independent from the other, but the control plane is active on only ONE single switch that is elected master of the stack.
 
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So how does a 3x1 team work in the switches when using cross-stack etherchannel?
Are both active on switch 1 and only 1 active on switch 2 giving me 3Gb/sec possible throughput?
 
cyr0n_k0r said:
So how does a 3x1 team work in the switches when using cross-stack etherchannel?
Are both active on switch 1 and only 1 active on switch 2 giving me 3Gb/sec possible throughput?
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Active from what standpoint? Given your scenario you want only 3 active, 2 on switch 1 and 1 on switch 2.. so there would only be 3 links in your etherchannel from the switch standpoint. You would see 4 total, but only 3 would be Switched/Up(active and ready). When I say "from the switch standpoint" Im refering to the stack master switch.. the second switch in the stack(slave) is not functional from a managment standpoint.
 
So if the 4th link in the team isn't active on the switch, how would switch 2 know to use it if both switch1's links failed?

Switch1: nic1 (active), nic2 (active)
Switch2: nic3 (active), nic4 (failover)

In the above, if switch 1 fails, I would go from 3Gb/sec throughput to 1Gb/sec? I thought I would go from 3Gb/sec to 2Gb/sec because nic4 would become active since it detected that nic1 and nic2 are down.
 
Etherchannel isn't a passive failover technology, its active meaning that once a link is failed its going to actively remove the failed link from the bundle and put the failed links traffic over another link that is up and active.

If you want a reactive failover technology what you want to look at is flex-links, though I believe you would need to do that between two etherchannels. Why is it that you want a failover NIC? Why not have all of the links forward traffic and have each one be a potential failover link?
 
For reference, the stacking cables you saw are nothing more than GigE modules with integrated cables, I've used em before.
 
Do NOT run an etherchannel between two switches that are not Cross-Stack etherchannel supported. No No No!

The group clustering is simply the convenience of having a single IP management interface for a group of switches that really have no special requirement except to be on the same network. That is, they are not specifically stacked, trunked or anything else like that.

As for passive links on etherchannel, it can be done by specifying a standby/spare link, but why would you do that? You would be wasting a whole link that could be load balancing traffic the whole time and still providing fail-over.

If you need to have a redundant etherchannel between switches, that is cross-stack, go with the 3750's. I use them in our virtualization environment and they have a dedicated 2x32Gb stacking bus and support cross channel etherchannel.

If you only need to spread active links between two switches (not in an etherchannel) you can use pretty much any switch, then supply an adequate trunk between the two (etherchannel) [that is the two switches have an etherchannel bond between the two switches, but end devices are not etherchanneled between the two switches], however recognize your bandwidth limits as the number of links in the channel which is usually limited to 8 active channels. Also consider your traffic, if you are sending a bulk of traffic from one host to one destination, etherchannel will not gain you and bandwidth, just redundancy. In a one-to-one or one-to-a-few traffic flow you should get a stacking switch.
 
xphil3 said:
He decided to go with a dell....
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Haha, sorry!
I looked at the 3750G's and I just can't afford them right now. I even found some great deals on them, but my budget just doesn't allow for $6500 each.

I went with the Dell Powerconnect 6248's and I'll use those for a year or two until I can afford them 3750's.
 
All the servers are Dell, storage too. It was either Cisco or Dell. I like to keep things consistent in the racks. I don't want cisco firewalls with hp switches with dell servers, etc.
 
cyr0n_k0r said:
All the servers are Dell, storage too. It was either Cisco or Dell. I like to keep things consistent in the racks. I don't want cisco firewalls with hp switches with dell servers, etc.
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You think your servers and network hardware have to match...?
 
Well, personally, I only buy blue routers and switches. If I went with black, it totally wouldn't match, and my girlfriend always tells me not to mix blue and black.

Duh...
 
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