02-25-2007 08:05 PM - edited 03-03-2019 03:55 PM
On my business SBC static plan I have 5 static ips.
I have the 2wire modem setup as a bridge, a gateway address assigned to the cisco router, a public ip assigned to the cisco router, and a public ip assigned to the firewall that then does NAT to private addresses.
I setup the cisco router to assign an IP from SBC automatically via PPPOE on the Dialer1 interface that is assigned to the 0/1 ethernet interface. The address assigned is xx.xx.xx.230/32.
I TRY to set the 0/0 ethernet statically to xx.xx.xx.225 255.255.255.248, which is the subnet SBC provides me. The router throws an error: xx.xx.xx.224 overlaps with Dialer1.
I can set the router to xx.xx.xx.225 or xx.xx.xx.226 with subnet 255.255.255.252, and everything works.
However I need all of my 5 IP addresses. Setting the subnet mask to 255.255.255.252 does not allow me the full range: 225 to 229.
Anyone have any idea what is going on here?
Current configuration : 1248 bytes
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname xxxxxxxxxx
!
boot-start-marker
boot-end-marker
!
enable secret 5 xxxxxxxxxxxxxx
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
no aaa new-model
ip subnet-zero
ip cef
!
!
!
vpdn enable
!
vpdn-group 1
request-dialin
protocol pppoe
!
no ftp-server write-enable
!
!
!
!
interface FastEthernet0/0
description LAN
ip address xx.xx.xx.225 255.255.255.252
duplex auto
speed auto
!
interface FastEthernet0/1
description WAN
no ip address
speed auto
pppoe enable
pppoe-client dial-pool-number 1
!
interface Dialer1
ip address negotiated
ip mtu 1492
encapsulation ppp
no ip mroute-cache
dialer pool 1
dialer-group 1
no cdp enable
ppp authentication pap callin
ppp chap hostname hostname@sbcglobal.net
ppp chap password 0 apasswordishere
ppp pap sent-username hostname@sbcglobal.netpassword 0 apasswordishere
!
ip classless
ip route 0.0.0.0 0.0.0.0 Dialer1
ip http server
!
!
dialer-list 1 protocol ip permit
!
control-plane
!
!
line con 0
password apasswordishere
login
line aux 0
line vty 0 4
password apasswordishere
login
!
end
02-26-2007 12:09 AM
Hi
it looks like your ip address that is getting dynamically allocated is coming out of the same subnet that has been allocated to you. So when you try and configure your internal interface with a /29 mask it overlaps with your dialer interface ie.
subnet = x.x.x.224
broadcast = x.x.x.231
Useable address = x.x.x.225 -> x.x.x.230
You cannot configure the same subnet on two different router interfaces.
Does your firewall sit behind your router and do you want to use the /29 network between the internal interface of your router and the external interface of your firewall ?.
If so you need to talk to your provider to understand why the address your negotiating on your dialer interface is out of the /29 network.
HTH
Jon
03-01-2007 06:28 PM
You are correct. Instead of calling my ISP, I got a workaround from another forum:
I used the commands:
int Dialer1
ip unnumbered fastethernet 0/0
To change the Dialer1 connection so that it mirros the 0/0 ip. I then changed 0/0 to xx.xx.xx.225/29, and now I can use 4 more addresses. :D
03-02-2007 07:25 AM
Quick note-
You can have SBC set up the DSL modem so that the PPPoE session is always on, so the router doesn't need to send the CHAP info to it to initiate the session. Then you don't even need to use a dialer interface - you can just put one of the static IPs on your FastE interface.
It'll take you 20 minutes to get to SBC tier 2 support, and then 20 seconds for them to make the change!
P
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