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Secondary addresses and static DHCP

My bloody ISP has gone and broken my setup and being only a bi-occasional IOS hack I've exhausted my alternatives.

I have a 1605R.

I have 5 static IPs from the ISP and previously I used the first as primary and the rest as secondaries for linking several inside services to the outside (eg. 3 different ftp servers that I want assessable from the outside):

interface Ethernet0 description connected to ADSL ip address xxx.xxx.207.104 255.255.248.0 secondary ip address xxx.xxx.207.105 255.255.248.0 secondary ip address xxx.xxx.207.106 255.255.248.0 secondary ip address xxx.xxx.207.107 255.255.248.0 secondary ip address xxx.xxx.207.103 255.255.248.0 ip access-group 101 in ip nat outside

Now the ISP has change something whereby things will not route unless you request your static IP via DHCP (it is mapped by registering the MAC address of the interface). So basically I have to change the above to:

interface Ethernet0 description connected to ADSL ip address dhcp ip access-group 101 in ip nat outside

and remove:

ip route 0.0.0.0 0.0.0.0 xxx.xxx.200.1

Everything on the xxx.xxx.200.103 then works fine and 90% of things work as they used to. However without the secondaries I loose things like having outside access to other ftp and web servers mapped like these examples:

ip nat inside source static tcp 172.16.0.4 21 xxx.xxx.207.105 21 extendable ip nat inside source static tcp 172.16.0.4 20 xxx.xxx.207.105 20 extendable ip nat inside source static tcp 172.16.0.10 80 xxx.xxx.207.105 80 extendable

Now there may be some way to fix/kludge this with static routes and/or playing around with arp but I can't get it to work. I also suspect I need to tweak the rip settings since without the secondary entries on the interface I loose automatic advertising and setting Ethernet0 to passive may not work. This is my current rip section:

router rip version 2 passive-interface Ethernet0 network 172.16.0.0 no auto-summary

Thanks for any help!

Reply to
Daryle A. Tilroe
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So just to follow-up to my previous message; I think that the above secondary listings may (when things were working fine before the ISP fubar'd things) have been redundant. It appears that the mappings like the ones below below:

etc. serve to make the correct arp entries:

Internet xxx.xxx.207.106 - 0030.94be.yyyy ARPA Ethernet0 Internet xxx.xxx.207.107 - 0030.94be.yyyy ARPA Ethernet0 Internet xxx.xxx.207.104 - 0030.94be.yyyy ARPA Ethernet0 Internet xxx.xxx.207.105 - 0030.94be.yyyy ARPA Ethernet0 Internet xxx.xxx.207.103 - 0030.94be.yyyy ARPA Ethernet0

(where all the 0030.94be.yyyy are identical MAC addresses)

Anyhow, it now seems that the main problem is the need to trigger the static DHCP request to the ISP in order to get their router to route to any of my IPs. Of course their system does not allow you to put in the same MAC for multiple IPs. I wonder if there is some way to have the router make the multiple DHCP requests for different MACs and then have the Ethernet0 interface with multiple MACS bound to it?

Reply to
Daryle A. Tilroe

It would seem that you are going to have to change from routing to bridging and setup each of your PC's to reuest an IP address via DHCP. Those DHCP requests will be need to be bridged to the Ethernet interface facing the ISP.

Reply to
Merv

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