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Virtualization with PowerVM > The Hardware Management Console > Connecting Managed Systems

Configuring a private DHCP Network

In most cases, DHCP is used to connect managed systems to an HMC. To do this, at least one of the network interfaces on the HMC must be configured for DHCP. The HMC is then the DHCP server in the connected network, and the managed systems or the FSPs and/or eBMCs of the managed systems are then DHCP clients. In principle, the administrator of an HMC can decide which IP address range should be managed via DHCP. However, in almost all cases it is easier to use one of the DHCP networks already provided by IBM.

The following shows the configuration of DHCP on an HMC using a concrete example. The HMC with the name hmc01 already has a network interface that is configured for DHCP. The configuration of the interfaces can be displayed with the command “hmc lsnet“:

LPAR-Tool
$ hmc lsnet hmc01
INTER  IPV4           IPV4             IPV4  DHCP    DHCP                 JUMBO          
FACE   ADDR           NETMASK          DHCP  SERVER  SERVERRANGE          FRAME  SPEED  DUPLEX  TSO
eth0   172.16.131.21  255.255.255.0    off   off     -                    off    auto   auto    -
eth1   10.0.0.1       255.255.255.0    off   on      10.0.0.2,10.0.0.254  off    auto   auto    -
eth2   0.0.0.0        255.255.255.0    off   off     -                    off    auto   auto    -
eth3   0.0.0.0        255.255.255.0    off   off     -                    off    auto   auto    -
eth4   0.0.0.0        255.255.255.255  off   off     -                    off    auto   auto    -
eth5   0.0.0.0        255.255.255.255  off   off     -                    off    auto   auto    -
$
HMC-CLI
hscroot@hmc01:~> lshmc -n
hmc01,domain=,description=,"ipaddr=172.16.131.21,10.0.0.1,0.0.0.0,0.0.0.0,0.0.0.0,0.0.0.0","networkmask=255.255.255.0,255.255.255.0,255.255.255.0,255.255.255.0,255.255.255.0,255.255.255.0",gateway=172.16.131.1,nameserver=,dns=disabled,domainsuffix=,slipipaddr=10.253.0.1,slipnetmask=255.255.0.0,"ipaddrlpar=172.16.131.21,10.0.0.1","networkmasklpar=255.255.255.0,255.255.255.0","clients=10.0.0.3,10.0.0.7,10.0.0.5,10.0.0.4,10.0.0.6,10.0.0.2",ipv6addrlpar=,ipv4addr_eth0=172.16.131.21,ipv4netmask_eth0=255.255.255.0,ipv4dhcp_eth0=off,dhcpserver_eth0=off,ipv6addr_eth0=,ipv6auto_eth0=off,ipv6privacy_eth0=off,ipv6dhcp_eth0=off,lparcomm_eth0=off,jumboframe_eth0=off,speed_eth0=auto,duplex_eth0=auto,tso_eth0=,ipv4addr_eth1=10.0.0.1,ipv4netmask_eth1=255.255.255.0,ipv4dhcp_eth1=off,dhcpserver_eth1=on,"dhcpserverrange_eth1=10.0.0.2,10.0.0.254",ipv6addr_eth1=,ipv6auto_eth1=off,ipv6privacy_eth1=off,ipv6dhcp_eth1=off,lparcomm_eth1=off,jumboframe_eth1=off,speed_eth1=auto,duplex_eth1=auto,tso_eth1=,ipv4addr_eth2=0.0.0.0,ipv4netmask_eth2=255.255.255.0,ipv4dhcp_eth2=off,dhcpserver_eth2=off,ipv6addr_eth2=,ipv6auto_eth2=off,ipv6privacy_eth2=off,ipv6dhcp_eth2=off,lparcomm_eth2=off,jumboframe_eth2=off,speed_eth2=auto,duplex_eth2=auto,tso_eth2=,ipv4addr_eth3=0.0.0.0,ipv4netmask_eth3=255.255.255.0,ipv4dhcp_eth3=off,dhcpserver_eth3=off,ipv6addr_eth3=,ipv6auto_eth3=off,ipv6privacy_eth3=off,ipv6dhcp_eth3=off,lparcomm_eth3=off,jumboframe_eth3=off,speed_eth3=auto,duplex_eth3=auto,tso_eth3=,ipv4addr_eth4=0.0.0.0,ipv4netmask_eth4=255.255.255.0,ipv4dhcp_eth4=off,dhcpserver_eth4=off,ipv6addr_eth4=,ipv6auto_eth4=off,ipv6privacy_eth4=off,ipv6dhcp_eth4=off,lparcomm_eth4=off,jumboframe_eth4=off,speed_eth4=auto,duplex_eth4=auto,tso_eth4=,ipv4addr_eth5=0.0.0.0,ipv4netmask_eth5=255.255.255.0,ipv4dhcp_eth5=off,dhcpserver_eth5=off,ipv6addr_eth5=,ipv6auto_eth5=off,ipv6privacy_eth5=off,ipv6dhcp_eth5=off,lparcomm_eth5=off,jumboframe_eth5=off,speed_eth5=auto,duplex_eth5=auto,tso_eth5=
hscroot@hmc01:~>

The eth1 interface is already configured for DHCP and is already in use. The HMC hmc01 itself has the IP address 10.0.0.1 and manages the range 10.0.0.2 to 10.0.0.254 of IP addresses via DHCP. The network previously used to connect managed systems is to be dismantled. New managed systems are therefore to be connected via a new network. For a transitional period, older managed systems will still be operated using the older network (eth1 interface). The eth2 interface is to be used for the new network.

The possible DHCP network ranges preconfigured by IBM can be listed using the command “hmc lsnet” and the option “-D” (DHCP):

LPAR-Tool
$ hmc lsnet -D hmc01
SERVER         NETMASK        START_RANGE    END_RANGE
192.168.128.1  255.255.128.0  192.168.128.2  192.168.255.254
172.16.0.1     255.255.0.0    172.16.0.3     172.16.255.254
172.17.0.2     255.255.0.0    172.17.0.3     172.17.255.254
10.0.0.1       255.255.255.0  10.0.0.2       10.0.0.254
10.0.128.1     255.255.240.0  10.0.128.2     10.0.143.254
10.0.255.1     255.255.255.0  10.0.255.2     10.0.255.254
10.1.0.1       255.255.240.0  10.1.0.2       10.1.15.254
10.1.255.1     255.255.255.0  10.1.255.2     10.1.255.254
10.127.0.1     255.255.240.0  10.127.0.2     10.127.15.254
10.127.255.1   255.255.255.0  10.127.255.2   10.127.255.254
10.128.0.1     255.255.240.0  10.128.0.2     10.128.15.254
10.128.128.1   255.255.255.0  10.128.128.2   10.128.128.254
10.128.240.1   255.255.240.0  10.128.240.2   10.128.255.254
10.254.0.1     255.255.255.0  10.254.0.2     10.254.0.254
10.254.240.1   255.255.240.0  10.254.240.2   10.254.255.254
10.255.0.1     255.255.255.0  10.255.0.2     10.255.0.254
10.255.128.1   255.255.240.0  10.255.128.2   10.255.143.254
10.255.255.1   255.255.255.0  10.255.255.2   10.255.255.254
$
HMC-CLI
hscroot@hmc01:~> lshmc -D
server=192.168.128.1,netmask=255.255.128.0,start_range=192.168.128.2,end_range=192.168.255.254
server=172.16.0.1,netmask=255.255.0.0,start_range=172.16.0.3,end_range=172.16.255.254
server=172.17.0.2,netmask=255.255.0.0,start_range=172.17.0.3,end_range=172.17.255.254
server=10.0.0.1,netmask=255.255.255.0,start_range=10.0.0.2,end_range=10.0.0.254
server=10.0.128.1,netmask=255.255.240.0,start_range=10.0.128.2,end_range=10.0.143.254
server=10.0.255.1,netmask=255.255.255.0,start_range=10.0.255.2,end_range=10.0.255.254
server=10.1.0.1,netmask=255.255.240.0,start_range=10.1.0.2,end_range=10.1.15.254
server=10.1.255.1,netmask=255.255.255.0,start_range=10.1.255.2,end_range=10.1.255.254
server=10.127.0.1,netmask=255.255.240.0,start_range=10.127.0.2,end_range=10.127.15.254
server=10.127.255.1,netmask=255.255.255.0,start_range=10.127.255.2,end_range=10.127.255.254
server=10.128.0.1,netmask=255.255.240.0,start_range=10.128.0.2,end_range=10.128.15.254
server=10.128.128.1,netmask=255.255.255.0,start_range=10.128.128.2,end_range=10.128.128.254
server=10.128.240.1,netmask=255.255.240.0,start_range=10.128.240.2,end_range=10.128.255.254
server=10.254.0.1,netmask=255.255.255.0,start_range=10.254.0.2,end_range=10.254.0.254
server=10.254.240.1,netmask=255.255.240.0,start_range=10.254.240.2,end_range=10.254.255.254
server=10.255.0.1,netmask=255.255.255.0,start_range=10.255.0.2,end_range=10.255.0.254
server=10.255.128.1,netmask=255.255.240.0,start_range=10.255.128.2,end_range=10.255.143.254
server=10.255.255.1,netmask=255.255.255.0,start_range=10.255.255.2,end_range=10.255.255.254
hscroot@hmc01:~>

For the new network, we select the DHCP network 10.127.255/24. This network is not currently used on any of our HMCs.

Such a preconfigured DHCP network can be easily configured with the command “hmc chnet”:

LPAR-Tool
$ hmc chnet hmc01 eth2 10.127.255.1 dhcpserver=on
$
HMC-CLI
hscroot@hmc01:~> chhmc -c network -s modify -a 10.127.255.1 --dhcpserver on -i eth2
hscroot@hmc01:~>

To do this, all you need to do is specify a server address from the list above (in our case 10.127.255.1) and the attribute dhcpserver=on in addition to the interface. The associated network mask and the range of DHCP IP addresses are then taken from the list of preconfigured DHCP network ranges.

Checking the configuration with “hmc lsnet” shows that the interface is correctly configured for DHCP:

LPAR-Tool
$ hmc lsnet hmc01
INTER  IPV4           IPV4             IPV4  DHCP    DHCP                         JUMBO          
FACE   ADDR           NETMASK          DHCP  SERVER  SERVERRANGE                  FRAME  SPEED  DUPLEX  TSO
eth0   172.16.131.21  255.255.255.0    off   off     -                            off    auto   auto    -
eth1   10.0.0.1       255.255.255.0    off   on      10.0.0.2,10.0.0.254          off    auto   auto    -
eth2   10.127.255.1   255.255.255.0    off   on      10.127.255.2,10.127.255.254  off    auto   auto    -
eth3   0.0.0.0        255.255.255.0    off   off     -                            off    auto   auto    -
eth4   0.0.0.0        255.255.255.255  off   off     -                            off    auto   auto    -
eth5   0.0.0.0        255.255.255.255  off   off     -                            off    auto   auto    -
$
HMC-CLI
hscroot@hmc01:~> lshmc -n
hostname=hmc01,domain=,description=,"ipaddr=172.16.131.21,10.0.0.1,10.127.255.1,0.0.0.0,0.0.0.0,0.0.0.0","networkmask=255.255.255.0,255.255.255.0,255.255.255.0,255.255.255.0,255.255.255.0,255.255.255.0",gateway=172.16.131.1,nameserver=,dns=disabled,domainsuffix=,slipipaddr=10.253.0.1,slipnetmask=255.255.0.0,"ipaddrlpar=172.16.131.21,10.0.0.1,10.127.255.1","networkmasklpar=255.255.255.0,255.255.255.0,255.255.255.0","clients=10.0.0.3,10.0.0.7,10.0.0.5,10.0.0.4,10.0.0.6,10.0.0.2",ipv6addrlpar=,ipv4addr_eth0=172.16.131.21,ipv4netmask_eth0=255.255.255.0,ipv4dhcp_eth0=off,dhcpserver_eth0=off,ipv6addr_eth0=,ipv6auto_eth0=off,ipv6privacy_eth0=off,ipv6dhcp_eth0=off,lparcomm_eth0=off,jumboframe_eth0=off,speed_eth0=auto,duplex_eth0=auto,tso_eth0=,ipv4addr_eth1=10.0.0.1,ipv4netmask_eth1=255.255.255.0,ipv4dhcp_eth1=off,dhcpserver_eth1=on,"dhcpserverrange_eth1=10.0.0.2,10.0.0.254",ipv6addr_eth1=,ipv6auto_eth1=off,ipv6privacy_eth1=off,ipv6dhcp_eth1=off,lparcomm_eth1=off,jumboframe_eth1=off,speed_eth1=auto,duplex_eth1=auto,tso_eth1=,ipv4addr_eth2=10.127.255.1,ipv4netmask_eth2=255.255.255.0,ipv4dhcp_eth2=off,dhcpserver_eth2=on,"dhcpserverrange_eth2=10.127.255.2,10.127.255.254",ipv6addr_eth2=,ipv6auto_eth2=off,ipv6privacy_eth2=off,ipv6dhcp_eth2=off,lparcomm_eth2=off,jumboframe_eth2=off,speed_eth2=auto,duplex_eth2=auto,tso_eth2=,ipv4addr_eth3=0.0.0.0,ipv4netmask_eth3=255.255.255.0,ipv4dhcp_eth3=off,dhcpserver_eth3=off,ipv6addr_eth3=,ipv6auto_eth3=off,ipv6privacy_eth3=off,ipv6dhcp_eth3=off,lparcomm_eth3=off,jumboframe_eth3=off,speed_eth3=auto,duplex_eth3=auto,tso_eth3=,ipv4addr_eth4=0.0.0.0,ipv4netmask_eth4=255.255.255.0,ipv4dhcp_eth4=off,dhcpserver_eth4=off,ipv6addr_eth4=,ipv6auto_eth4=off,ipv6privacy_eth4=off,ipv6dhcp_eth4=off,lparcomm_eth4=off,jumboframe_eth4=off,speed_eth4=auto,duplex_eth4=auto,tso_eth4=,ipv4addr_eth5=0.0.0.0,ipv4netmask_eth5=255.255.255.0,ipv4dhcp_eth5=off,dhcpserver_eth5=off,ipv6addr_eth5=,ipv6auto_eth5=off,ipv6privacy_eth5=off,ipv6dhcp_eth5=off,lparcomm_eth5=off,jumboframe_eth5=off,speed_eth5=auto,duplex_eth5=auto,tso_eth5=
hscroot@hmc01:~>

The new DHCP network can then be used immediately to connect managed systems. With this configuration, the HMC supports the connection of managed systems via DHCP using both the eth1 and eth2 interfaces!