Hello everyone.
Mi name is Kristian.
Recently i am configured a UBR10k to give to the clients public ip´s but i get stuck because in the Bundle when configure a ip secondary with a public ip for gateway the request to me dhcp server arrives with ip of the normal gateway.
I attached part of the configuration to illustrate the problem.
interface Bundle80
no ip address
cable arp filter request-send 3 2
cable arp filter reply-accept 3 2
!
interface Bundle80.1
ip vrf forwarding internet
ip address 10.156.160.1 255.255.224.0 secondary
ip address 10.156.128.1 255.255.192.0 secondary
ip address 10.156.192.1 255.255.240.0 secondary
ip address 10.156.208.1 255.255.240.0 secondary
ip address 10.156.228.1 255.255.252.0 secondary
ip address 10.156.232.1 255.255.252.0 secondary
ip address 189.197.0.1 255.255.192.0 secondary
(This is the scope in the dhcp server for the cpe´s)
ip address 10.156.0.1 255.255.192.0
(This is the scope in the dhcp server for the cablemodems)
ip access-group filtro in
no ip redirects
cable source-verify dhcp
cable dhcp-insert downstream-description
cable dhcp-giaddr policy
cable helper-address 10.0.156.129
The request from the pc arrives via ip 10.156.0.1 and not for the secondary 189.197.0.1.
Any ideas?
somebody has configured a cmts to give publics ip´s?
Best regards and apologize for mi english.
Hello Kristian,
I see two points in your situation:
1st point: Your DHCP server receives all relayed DISCOVER and REQUEST from the IP 10.156.0.1, which is the primary IP address of the bundle.
By default, the CMTS relays all DHCP DISCOVER and REQUEST with its primary IP, without considering if this is a CM or a CPE.
You can use the command "cable dhcp-giaddr policy" (in the context of "interface bundle") to change this behavior and make the CMTS use the primary address for the cable modems and the secondary for the hosts (or CPEs):
http://www.cisco.com/en/US/docs/ios/12_0t/12_0t4/feature/guide/Giaddrcp....
This is a helpful command, as the CMTS does split the DHCP DISCOVER and REQUEST coming from a CM or from a CPE.
With this command, you would receive requests from CMs relayed from 10.156.0.1 (the primary IP) and requests from CPEs relayed from 10.156.160.1 (the first secondary IP)
But, I see that you have plenty of private secondaries subnets (10.156.x.0). If these subnets are currently used to increase the number of CMs (because the primary subnet was maybe too small), then the use of "cable dhcp-giaddr policy" could make some confusion and break the current IP allocation to your CMs and to your CPEs.
However, if all these 10.156.x.0 (except the primary) are already used for providing private addresses to your CPEs, then this command will do the work. You'd probably will have to make some changes in your DHCP configuration file.
2nd point:
If you use or not the above provided command, the CMTS could not know in advance (before the DHCP server provides) the IP address that will be used by the CPE. So he will never be able to relay a DHCP DISCOVER or REQUEST with the public IP address you configured on the CMTS (189.197.0.1). Depending the presence of the command "cable dhcp-giaddr policy", he will either use the primary IP address (if that command is absent) or the first secondary IP address (if that command is present). It is then the task of the DHCP server to decide if it will provides a private IP address to the CPE or a public one.
On the DHCP server, I think you will have to use some statements such as "shared-network" and embedds some "subnet" in that "shared-network".
Hope this helps.
Bag'
Thanks for the replay Baghee.
I already test the comand "cable dhcp-giaddr policy", "cable dhcp-giaddr policy strict" and "cable dhcp-giaddr primary" bu without sucess.
The next step is check in the dhcp server the comands that you recomends.
Thanks.