topic Re: secondary ip issue in Switching

secondary ip issue

saquib.tandel — Thu, 07 Mar 2019 00:10:04 GMT

We are caught in a weird setup. Recently our company acquired another company. IT services came to our basket for support. Users are running out of IP address. Temporary to fix the issue we added secondary ip address but doesnt seems to help.

(( Internet-cloud))-----Router----PIX-------3560-------LAN

On 3560

vlan 1

ip address 192.168.1.1 255.255.255.0

ip address 192.168.2.1 255.255.255.0 secondary

ip dhcp smart-relay

router eigrp 1

network 192.168.1.0

network 192.168.2.0

ip route 0.0.0.0 0.0.0.0 firewall

DHCP and DNS services are running on same server : 192.168.1.10 255.255.255.0

ISA Server : 192.168.1.100 255.255.255.0

ISA Server is the default-gateway for all users

ISA Server IP is natted on PIX to allow internet browsing

DHCP server got two scope; one for primary IP and one for secondary ip

Any help to see how can users get secondary ip address automatically

thanks

Re: secondary ip issue

jonathanaxford — Sun, 20 Mar 2011 18:03:37 GMT

Hi there,

You may need an IP helper address on the VLAN 1 interface to ensure that DHCP broadcasts from the secondary subnets get through OK.

interface vlan 1

ip helper-address 192.168.1.10

Hope this helps

Jonathan

Re: secondary ip issue

saquib.tandel — Sun, 20 Mar 2011 19:50:22 GMT

I tested IP Helper-address command but didnt help, in this scenario ip helper-address command is not needed as user/server are in the same vlan

Users get ip from primary range but from secondary range users dont get ip address.

DHCP/DNS default gateway is ISA server and users default-gateway is ISA server.

ISA server is with single network card.

ISA Server default-gateway is the 3560-switch

ISA server is running Windows 2003 and microsoft ISA 2006

thanks

Re: secondary ip issue

jonathanaxford — Sun, 20 Mar 2011 21:08:22 GMT

Hi there,

What DHCP service are you using? I remember something about "Superscopes" being required when using MS DHCP with secondary IP addressing. It basically tells the DHCP server to group multiple subnets into a single logical DHCP pool...

The following technet article explains this in more detail:

http://technet.microsoft.com/en-us/library/cc757614%28WS.10%29.aspx

Hope this helps

Jonathan

Re: secondary ip issue

saquib.tandel — Mon, 21 Mar 2011 06:51:57 GMT

Thank you

ISA Server is with one network card, how can it forward request for other networks. Do i need to add "Route add " command on Microsoft ISA