02-15-2008 12:39 PM - edited 03-05-2019 09:11 PM
Hi All
I was thinking of picking up a Cisco 877W router to act as my wireless modem/router. However my ISP will not support Cisco though they have provided a basic configuration to get the ADSL up and running.
I am not sure I understand the configuration and was wondering if someone would be kind enough to explain the parts marked in red in the attached configuration.
I am not sure that I understand why the ATM0 interface has no IP address assigned but the Eth 0 interface does and how they tie together.
Also I assume that I need to create a VLAN for my inside IP addresses (192.168.x.x) and configure NAT, a DHCP server and appropriate ACL's?
If anybody could provide a complete (ADSL, NAT & DHCP) example config, it would be much appreciated.
Extra Information: Currently my public IP is dynamically assigned though in the near future I hope to switch to having a static IP address assigned.
Best Regards & TIA,
Michael
Solved! Go to Solution.
02-15-2008 04:57 PM
Michael,
Please see this link:
http://www.cisco.com/en/US/tech/tk175/tk15/technologies_configuration_example09186a008071a729.shtml
You will need ip address negotiated under dialer1 if you are using dynamic IP address from the provider.
HTH,
__
Edison.
02-16-2008 08:04 AM
> In the portion of configuration below, which also came from my ISP and I am told is for use with a static
> IP address(es), it appears that the static IP address (or one from a range) is assigned to Interface Vlan1.
> Is this correct?
You can assign the IP address to interface Vlan1 or to interface dialer1. If you assign to interface Vlan1, you can assign other public IP addresses to devices connected to FastEthernet0 thru FastEthernet3 since they also belong to Vlan1. If you assign the IP address to dialer1, you can only use that IP address on that interface (like a point-to-point connection).
The unnumbered command will clone the IP address from Vlan1 in Dialer1.
> If I then wanted to have the router assign private IP addresses to my inside clients.
> I would do the following, ......
Correct.
> If an ISP provided a number of public IP addresses (say a /29 subnet),
> is it possible to configure a NAT pool and have these 6 IP addresses perform overloading?
Yes, you can also assign static IP address to devices connected in FasEthernet0 thru 3 as I explained above.
02-15-2008 04:57 PM
Michael,
Please see this link:
http://www.cisco.com/en/US/tech/tk175/tk15/technologies_configuration_example09186a008071a729.shtml
You will need ip address negotiated under dialer1 if you are using dynamic IP address from the provider.
HTH,
__
Edison.
02-16-2008 05:09 AM
Hi Edison
Cheers for the quick response and the link. It was very helpful and also provided another link to a page with step by step troubleshooting, which is very helpful.
Can I ask a couple more questions please,
In the portion of configuration below, which also came from my ISP and I am told is for use with a static IP address(es), it appears that the static IP address (or one from a range) is assigned to Interface Vlan1.
Is this correct?
And the line "ip unnumbered Vlan1" under the Dialer1 interface is tying the Dialer1 interface to the static IP address.
Is this correct?
If I then wanted to have the router assign private IP addresses to my inside clients. I would do the following,
1. Create VLAN2
2. Assign some/all of the Fast Ethernet ports to VLAN2.
3. Create interface VLAN2 and assign an IP address in the private range to this interface (say 192.168.1.1).
4. Configure a DHCP Pool for this range, excluding the IP address assigned to the interface.
5. Configure interface VLAN2 as my "nat inside" interface and interface Dialer1 as my "nat outside interface
Is this correct?
Last Question (for now at least :) )
If an ISP provided a number of public IP addresses (say a /29 subnet), is it possible to configure a NAT pool and have these 6 IP addresses perform overloading?
Thank you for your time and patience,
Best Regards,
Michael
+++++ Configuration Extract from which prompted questions above ++++++
interface ATM0
no ip address
no atm ilmi-keepalive
pvc 8/35
encapsulation aal5snap
pppoe-client dial-pool-number 1
!
dsl operating-mode auto
!
interface FastEthernet0
!
interface FastEthernet1
!
interface FastEthernet2
!
interface FastEthernet3
!
interface Virtual-Dot11Radio1
no ip address
!
interface Vlan1
ip address XXXXXX 255.255.255.252 ! PUBLIC ADDRESS FOR LINE
ip tcp adjust-mss 1400
!
interface Dialer1
ip unnumbered Vlan1
ip virtual-reassembly
encapsulation ppp
ip tcp adjust-mss 1400
dialer pool 1
dialer remote-name redback
dialer-group 1
ppp authentication pap chap callin
ppp chap hostname eircom
ppp chap password 7 141500040D00282A2A2C62
!
ip classless
ip route 0.0.0.0 0.0.0.0 Dialer1
!
++++++ End of Configuration Extract ++++++
02-16-2008 08:04 AM
> In the portion of configuration below, which also came from my ISP and I am told is for use with a static
> IP address(es), it appears that the static IP address (or one from a range) is assigned to Interface Vlan1.
> Is this correct?
You can assign the IP address to interface Vlan1 or to interface dialer1. If you assign to interface Vlan1, you can assign other public IP addresses to devices connected to FastEthernet0 thru FastEthernet3 since they also belong to Vlan1. If you assign the IP address to dialer1, you can only use that IP address on that interface (like a point-to-point connection).
The unnumbered command will clone the IP address from Vlan1 in Dialer1.
> If I then wanted to have the router assign private IP addresses to my inside clients.
> I would do the following, ......
Correct.
> If an ISP provided a number of public IP addresses (say a /29 subnet),
> is it possible to configure a NAT pool and have these 6 IP addresses perform overloading?
Yes, you can also assign static IP address to devices connected in FasEthernet0 thru 3 as I explained above.
02-16-2008 08:30 AM
Hi Edison
Cheers for your speedy and extremely helpful responses. Much appreciated.
Best Regards,
Michael
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