Replacing Cisco DHCP to Linux 2

[dvtestguy]

Hi,

I'm replacing an older Cisco Router which was being used for DHCP Pools, NAT, ACL in favor of Ubuntu Linux Server.

I've loaded the SW, started configuring, but had a few questions.

1) My Cisco DHCP Pools & Sub-Interfaces were setup due to Vlan traffic isolation per Client. On my Linux server, do I have to recreate the same sub-interfaces?

2) See Cisco configs below...Vlans/Interfaces = 500-999

ip dhcp pool vlan500
network 50.50.50.0 255.255.255.240
dns-server 10.15.12.100 10.10.1.10
default-router 50.50.50.1
domain-name abc.efg.com
lease 10
!
ip dhcp pool vlan501
network 50.50.50.16 255.255.255.240
dns-server 10.15.12.100 10.10.1.10
default-router 50.50.50.17
domain-name abc.efg.com
lease 10
!
interface GigabitEthernet5/0.500
encapsulation dot1Q 500
ip address 50.50.50.1 255.255.255.240
ip access-group 100 in
ip nat inside
!
interface GigabitEthernet5/0.501
encapsulation dot1Q 501
ip address 50.50.50.17 255.255.255.240
ip access-group 100 in
ip nat inside
!

3) See Ubuntu Linux configs below:

/etc/network# cat interfaces
ETH0.500
# The primary network interface
auto eth0
# iface eth0 inet dhcp
iface eth0 inet static
address 10.15.12.11
netmask 255.255.255.0
network 10.15.12.0
broadcast 10.15.12.255
gateway 10.15.12.1

auto eth0:500
iface eth0:500 inet static
address 10.115.50.1
netmask 255.255.255.240
network 10.115.50.0
broadcast 10.115.50.255
gateway 10.115.50.1

/etc/dhcp3# cat dhcpd.conf
# A slightly different configuration for an internal subnet.
subnet 10.115.0.0 netmask 255.255.255.240 {
range 10.115.50.2 10.115.50.14;
# option domain-name-servers ns1.internal.example.org;
option domain-name "dvlab.acterna.com";
option routers 10.115.1.1;
option broadcast-address 10.115.1.255;
default-lease-time 600;
max-lease-time 7200;

Thanks!

 

[IRudebwoy]

Looks okay so far. I'm not too sure how one would handle 802.1q tagging in ubuntu. I could tell you how to do it in gentoo but that's another story.

You might try this for starters, via a quick search on the internet.

Have fun!

 

[tjbradford]

this is more of a cisco question, you need to create the scopes on the linux box for each subnet and in each vlan add the command ip-helper *.*.*.* the stars being the address of the linux server , this will cause the switch / router to wrap the broadcast and forward it to the dhcp server , the server will see where this originated and reply accordingly

goodluck

 

[IRudebwoy]

Per #1

My Cisco DHCP Pools & Sub-Interfaces were setup due to Vlan traffic isolation per Client.

That scenario would require the 802.1q tagging of the sub interfaces in the ubuntu DHCP server in order to keep the traffic isolated. The DHCP helper requires the DHCP protocol to be routed to and from the server which violates #1.