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ADSL modem <-> Cisco 877 <-> internal network problems!

Damien Silman
Level 1
Level 1

Hi all,

Due to some ongoing issues with dsl interface firmwares and the kit held in our ISP exchanges; we are havign to resort to substituting out the Cisco 877 ADSL atm interface and using a seperate router supplied by the ISP to make the initial connection.

I am struggling to get the 877 to do what I want it to now though; and have subsequently found it can only handle two VLANs.

So; my ISP provided router/modem connects to the net, anythign connected to it browses fine.

This is on subnet 192.168.1.0/24 and IP 192.168.1.254 is the router

I have a port on the 877 configured in this subnet, and in VLAN666 (so i can apply ip nat outisde)

This is on 192.168.1.139

Additionally I am using VLAN1 for corporate traffic on 172.30.59.0/24 subnet and if it could handle an additional VLAN I'd also be using 10.30.59.0/24 for voice, but that's a seperate issue (unless you have any helpful suggestions!)

The 877 can ping everything, unless I tell it to use source VLAN1.

Laptop connected to to VLAN1 can ping VLAN1, VLAN666 but not 192.168.1.254 or any internet based hosts.

ISP router can ping 192.168.1.139 on the 877 but no further.

This all stinks of NAT issues but I can't figure it out; config below:

ITTEST#show run

Building configuration...

Current configuration : 4282 bytes

!

! Last configuration change at 16:10:10 GMT Mon Nov 11 2013

! NVRAM config last updated at 16:10:14 GMT Mon Nov 11 2013

!

version 12.4

no service pad

service tcp-keepalives-in

service tcp-keepalives-out

service timestamps debug uptime

service timestamps log uptime

service password-encryption

!

hostname ITTEST

!

boot-start-marker

boot-end-marker

!

logging message-counter syslog

logging buffered 10240

logging console critical

enable secret

enable password

!

no aaa new-model

clock timezone GMT 0

clock summer-time BST recurring last Sun Mar 1:00 last Sun Oct 2:00

!

!

dot11 syslog

no ip source-route

ip dhcp excluded-address 172.30.59.1 172.30.59.100

!

ip dhcp pool dhcppool

   import all

   network 172.30.59.0 255.255.255.0

   default-router 172.30.59.1

   dns-server 172.30.59.1 172.20.0.120 172.20.0.121

   domain-name gratte.com

   update arp

!

!

ip cef

ip domain name gratte.com

ip name-server 192.168.1.254

ip name-server 172.20.0.120

ip name-server 172.20.0.121

!

!

!

!

!

!

crypto isakmp policy 1

encr 3des

authentication pre-share

group 2

crypto isakmp key <presharedkey> address xxx.xxx.xxx.xxx no-xauth

!

!

crypto ipsec transform-set 3DESSHA esp-3des esp-sha-hmac

!

crypto ipsec profile IPSEC-VPN

set transform-set 3DESSHA

!

!

archive

log config

  hidekeys

!

!

!

!

!

interface Tunnel0

description --- IPSec Tunnel to KX ---

ip address 172.30.60.1 255.255.255.0

ip ospf mtu-ignore

load-interval 30

tunnel source Vlan1

tunnel destination xxx.xxx.xxx.xxx

tunnel mode ipsec ipv4

tunnel protection ipsec profile IPSEC-VPN

!

interface ATM0

no ip address

shutdown

no atm ilmi-keepalive

!

interface FastEthernet0

description DATA

spanning-tree portfast

!

interface FastEthernet1

description VOICE

switchport access vlan 100

switchport voice vlan 100

spanning-tree portfast

!

interface FastEthernet2

shutdown

!

interface FastEthernet3

switchport access vlan 666

no cdp enable

spanning-tree portfast

!

interface Vlan1

ip address 172.30.59.1 255.255.255.0

ip nat inside

ip virtual-reassembly

!

interface Vlan2

no ip address

!

interface Vlan100

ip address 10.30.59.1 255.255.255.252

ip nat inside

ip virtual-reassembly

!

interface Vlan666

ip address 192.168.1.139 255.255.255.0

ip nat outside

ip virtual-reassembly

!

interface Dialer0

no ip address

!

ip default-gateway 192.168.1.254

ip forward-protocol nd

ip route 0.0.0.0 0.0.0.0 192.168.1.254

ip route 10.20.0.0 255.255.0.0 Tunnel0

ip route 10.21.0.0 255.255.0.0 Tunnel0

ip route 64.156.192.220 255.255.255.255 Tunnel0

ip route 64.156.192.245 255.255.255.255 Tunnel0

ip route 74.50.50.16 255.255.255.255 Tunnel0

ip route 74.50.63.14 255.255.255.255 Tunnel0

ip route 172.16.0.0 255.240.0.0 Tunnel0

ip route 172.30.59.0 255.255.255.0 Vlan1

no ip http server

no ip http secure-server

!

ip dns server

ip nat source list 100 interface Vlan1 overload

!

access-list 100 permit ip 172.30.59.0 0.0.0.255 any

!

!

!

snmp-server community  RO

snmp-server community  RW

!

control-plane

!

!

line con 0

password

login

no modem enable

line aux 0

line vty 0 4

password

login

!

scheduler max-task-time 5000

ntp server 72.8.140.222

end

Ultimately I'll be using this for a VPN, but I can't even get internet traffic currently.

Any ideas?

Thanks,

27 Replies 27

Hi,

I try to ping 192.168.1.254 or anything on the net from the laptop, the router gives me no debugging information.

My bad, sorry. transit traffic is not seen by debug output.

ping sourcing from vlan1 and and post sh ip nat tr output if it is empty then ping again this time with debug ip pack 199

and do debug ip nat

Regards

Alain

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ITTEST#ping 192.168.1.254 source vlan1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.168.1.254, timeout is 2 seconds:

Packet sent with a source address of 172.30.59.1

02:45:46: IP: s=172.30.59.1 (local), d=192.168.1.254, len 100, local feature, NAT(2), rtype 0, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE

02:45:46: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, sending

02:45:46: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, output feature, Post-routing NAT Outside(17), rtype 1, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE

02:45:46: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, sending full packet.

02:45:48: IP: s=172.30.59.1 (local), d=192.168.1.254, len 100, local feature, NAT(2), rtype 0, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE

02:45:48: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, sending

02:45:48: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, output feature, Post-routing NAT Outside(17), rtype 1, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE

02:45:48: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, sending full packet.

02:45:50: IP: s=172.30.59.1 (local), d=192.168.1.254, len 100, local feature, NAT(2), rtype 0, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE

02:45:50: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, sending

02:45:50: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, output feature, Post-routing NAT Outside(17), rtype 1, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE

02:45:50: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, sending full packet.

02:45:52: IP: s=172.30.59.1 (local), d=192.168.1.254, len 100, local feature, NAT(2), rtype 0, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE

02:45:52: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, sending

02:45:52: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, output feature, Post-routing NAT Outside(17), rtype 1, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE

02:45:52: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, sending full packet.

02:45:54: IP: s=172.30.59.1 (local), d=192.168.1.254, len 100, local feature, NAT(2), rtype 0, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE

02:45:54: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, sending

02:45:54: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, output feature, Post-routing NAT Outside(17), rtype 1, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE

02:45:54: IP: s=172.30.59.1 (local), d=192.168.1.254 (Vlan666), len 100, sending full packet.

Success rate is 0 percent (0/5)

ITTEST#

ITTEST#

ITTEST#sh ip nat tr output

                    ^

% Invalid input detected at '^' marker.

ITTEST#sh ip nat tr

Hi,

the command is sh ip nat translation

but it is doing post-nat routing so there should have been a nat translation

can you confirm anyway and turn off debugging: do u all in config mode

Regards

Alain

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Hi Alain,

Thanks for the help, I've turned the debugging off; not quite sure what you want me to try now, it still doesn't work...

Hi,

ping again and post output of sh ip nat translation to confirm there was natting in action or not

according to result we'll investigate further.

Regards

Alain

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ITTEST#ping 192.168.1.254 source vlan1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.168.1.254, timeout is 2 seconds:

Packet sent with a source address of 172.30.59.1

.....

Success rate is 0 percent (0/5)

ITTEST#show ip nat translation

ITTEST#

Hi,

ok so there is no translation finally.Can you post following:

-sh ip int Vlan1 | i Internet

-sh ip arp 192.168.1.254

- sh access-list 100

-sh ip cef 192.168.1.254

Can you also post a quick sketch of the network.

Regards

Alain

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ITTEST#sh ip int Vlan1 | i Internet

  Internet address is 172.30.59.1/30

ITTEST#sh ip arp 192.168.1.254

Protocol  Address          Age (min)  Hardware Addr   Type   Interface

Internet  192.168.1.254           0   7c03.d847.e488  ARPA   Vlan666

ITTEST#sh access-list 100

Extended IP access list 100

    10 permit ip 172.30.59.0 0.0.0.255 any

ITTEST#sh ip cef 192.168.1.254

192.168.1.254/32

  attached to Vlan666

Network layout would be:

PSTN/ADSL line -------> ISP modem/router ----------> fe0/3 Cisco 877 fe0/0 -----------> laptop

                                    192.168.1.254/24        192.168.1.139/24   172.30.59.1/24      172.30.59.123/24

Would that be enough detail?

Hi,

You configured Vlan1 as a /30 on the router but your attached host has a /24.

Can you change it to a /24 on the router and also change this:

ip nat source list 100 interface Vlan666 overload like this:

ip nat inside source list 100 interface Vlan666 overload

You should then be able to ping from host in vlan 1 to 192.168.1.254 and beyond

Regards

Alain

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Hi Alain,

Changing the ip nat source list 100 interface vlan666 overload to ip nat inside source list 100 interface vlan666 overload did the trick.

I've left the odd subnet on the vlan 1 address, as I use an IP in the same subnet for the tunnel interface as well, if the subnets of this IPs overlap, it doesn't let you set it. Odd I know, but when I originally made this config (well the predecessor to this one when we still used the atm interface), that was the only way I could get it to work as required, and it only meant losing the first handful of IPs in a subnet where we'd only be using about 50 IPs anyway.

Thanks a million for your help, got this router working as required just in time.

I just need to push the config on to another test router now (this one we were playing with is getting shipped out first thing tomorrow morning) and get the tunnel up, hadn't had the time to configure this on the receiving firewall though, so it may just work.

The one part I've changed initially with the hope that it'll work was the tunnel source:

interface Tunnel0

description --- IPSec Tunnel to KX ---

ip address 172.30.60.1 255.255.255.0

ip ospf mtu-ignore

load-interval 30

tunnel source Vlan1

tunnel destination xxx.xxx.xxx.xxx

tunnel mode ipsec ipv4

tunnel protection ipsec profile IPSEC-VPN

This was previously Dialer0, do you know if this will work?

Thanks!

Hi,

As long as the other VPN peer knows how to reach vlan1 then the tunnel should be up but you'll have to change the tunnel destination on this peer to vlan 1 ip  address.

Regards

Alain

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Hi Alain,

The VPN peer does not receive any traffic from the Public IP of the 877, so it seems the tunnel is not trying to be established. Any ideas?

Thanks again,

Hi

I've opened a new discussion for this piece as my original issue (from this discussion) is now solved.

New discussionis https://supportforums.cisco.com/thread/2251447

Thanks!

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