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Re: HMC DHCP address range



fixed

Be very very careful here. First, those provided address ranges are IMHO Ballistically stupid. Look carefully at some of them and you'll see that they are large enough to connect every Power System FSP ever manufactured. What were they thinking??

You cannot add additional ones sadly so your choices are to use those provided or use fixed addresses. That much is your call but I like using DHCP here.

So if you use a private network between the FSP and HMC (as I STRONGLY support-detail in another thread) you'll wonder why you care about what these addresses are. Some argue you don't but I'll show you that you do!

Suppose you choose the range 10.255.255.0/24 for your HMC to FSP network. This happens to be my favorite as it's top of range and it's 'only' 256 addresses. Your company's network uses addresses in the range 172.16.x.x. You are in good shape. But then along comes your firewall guy and says, HMMM, we've been handing out 192.168.x.x addresses when users connect with VPN and that's a problem because of all the home networking gear using those. I say we go way out there and pick 10.255.255.0 for our VPN users. Nobody is using that and it's not a conflict for 172.16.x.x so everybody is happy happy happy.... except you. This is because you can no longer access your HMC when connected over your VPN!! With a 10.255.255 address on your VPN when the HMC attempts to respond to you it drops that packet onto the 10.255.255.0 local network. Of course you are not there and you're stuck.

SO you must not only stay away from currently valid addresses in your network you must ALSO assure that your network team is aware of this range being in use so that they don't break something for you when you least expect it.

- Larry "DrFranken" Bolhuis

www.frankeni.com
www.iDevCloud.com
www.iInTheCloud.com

On 2/22/2014 2:50 PM, Steve Richter wrote:

I am in the HMC guided setup wizard. The wizard is asking "do you want to
specify this HMC as a DHCP server?" The wizard says to select as a DHCP
server "so that the managed systems on the network will be automatically
configured and discovered by the HMC".

But the drop down list of address ranges does not include the address of my
managed system, a 520 with an FSP address of 192.168.2.147. The closest
range in the dropdown list is 192.168.128.2 - 192.168.255.254.

Is there a way to add more address ranges to this drop down list? Should I
change the HMC address of the 520 to be in the range of one of the existing
ranges?

thanks,






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