IBM blade centre switches

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Mar 11th, 2008
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Hi all, Im new to ibm blades, I have seen in the back of some of our blades that we have 2 small switches in the back, both with 6 ports on them, my question is , how does the blade centre use these 2 switches and why are there 2 in it ?

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branfarm1 Tue, 03/11/2008 - 07:02
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I have an HP bladeSystem with Cisco switches in it and I assume they are fairly similar. Each of your blades will map to an internal port on the switches, 2 per host. The switches will have external ports that you can use for uplinks or to hook in other devices like you would a "normal" switch. So, for example, my HP BLadeEnclosure has 16 slots and my Cisco Bladesystem switch has 24 ports. 16 of those ports are for the blades, 2 ports are used internally for connections between the switches, and the remaining are used for uplinks or external connections. (There are actually 8 ports externally, but you can dedicate two to be used for the internal switch-switch connections -- not sure if it's the same on the IBM version.)

The reason you have two switches is for redundancy purposes. Each blade will map 1 port to each switch, so two NIC's per blade. Think of it just like if you had a server connected via CAT5 to two physical switches.

The great thing about the Bladeswitches is that you have all the functionality of a normal layer 2 switch in a small form-factor -- you can use all the advanced L2 features within the blade enclosure that you have available on other Cisco Catalyst switches.

Hope that helps!

glen.grant Tue, 03/11/2008 - 08:05
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Those ports are how they attach to the network. you can trunk, etherchannel or whatever you want for that blade. Those are basically 2950's on a card . The rest of the ports are internal to blade and attach the servers slots 1-14 to card when then switches it out those 4 ports to the network . There are 2 switches , usually 1 as primary and the other as backup if something happens to the primary. The switches run regular ios and looks like any other cisco ios switches with some added commands for link state failover etc...

carl_townshend Tue, 03/11/2008 - 08:55
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Hi there

So if I have 2 switches in the back of my blades, will each switch have its own ip address, or will there be one address for both switches. It looks like they are Nortel switches in this case.

how do I configure, Do I replicate the config on both switches? and will it load balance the uplink to my lan between the switches or will one switch be active the other standby ?


glen.grant Tue, 03/11/2008 - 11:47
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If they are nortels can't really help you there , on cisco's each switch will have its own address to manage it with just like a normal layer 2 switch . You actually put the ip address each switch thru the bladecenter management module .

carl_townshend Wed, 03/12/2008 - 07:45
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Hi there, with the cisco switches, how do these work on the blade centre? do both switches load balance, or is one a redundant switch, Also do you have make sure that both switches are configured the same as each blade has a connection to both ?

is this right ?

glen.grant Wed, 03/12/2008 - 13:17
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Blades have a connection to both and generally one is live with the other as failover .

chris.williamsEP Wed, 03/12/2008 - 14:45
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With the HP c7000 series BladeSystem, you could have up to 8 Cisco LAN switches in one blade chassis. The benefit of this would be for something like VMWare on Blades where you would need a lot of throughput for each physical server. With two bladeswitches (the most common configuration) each bladeserver will have two NICs that can be activated, each NIC will tie to one Cisco switch. These two NICs can be teamed together, but will only function in active/passive mode, b/c right now you cannot EtherChannel between two Cisco 30x0 series switches. This functionality is being released in May though when Cisco releases the 31x0 series bladeswitches. They use functionality like the 3750 'stackwise' technology, but do it over the BladeSystem backplane instead of a cable.

When you insert the Cisco bladeswitches, their Fa0 interface pulls a DHCP address from the Onboard Administrator IP range so you can access the GUI or telnet to them. I guess the short answer is that each bladeswitch is a separate L2 switch.



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