IPoATM RFC1483 Bridged - VODAFONE Portugal

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Aug 2nd, 2008
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Hi all, I'm trying configure an 877 ADSL Router to work with VODAFONE ADSL, butwithout success :(

The information of de ISP are:

Encapsulation: LLC SNAP


PVC: 0 35

IPoATM 1483 bridge mode


Modulation: ADSL2+

PCR 4000

SCR 4000

MBR 10

PVC Mapping disable

And my actual config are in attach

Somebody can tell me what's de problem?

Thanks in advance.

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Giuseppe Larosa Sun, 08/03/2008 - 01:58
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Hello Ivan,

may you post the output of sh atm pvc to understand if pvc 0/35 is up.

from sh int BVI1 do you see if the interface gets an IP address ?

To help the router to do its job you can define another vlan SVI vlan3 associate it with bridge-group1 and then associate one of the fast with vlan 3

int vlan3

no ip address

bridge-group 1

int fast 3

switcport mode access

switchport access vlan 3

no keepalive

interface bv1

ip address dhcp

This could help but first of all the ATM PVC must be up.

You see from sh int atm0:

>>> Last input 00:19:28, output 00:00:00, output hang never

So verify the pvc state with sh atm pvc

Hope to help


ivanmoreira1130 Sun, 08/03/2008 - 03:09
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Hi Giuseppe, thanks for your help!

After insert this configuration that you ordered, I already obtain IP conectivity, however the IP is being attributed in my laptop connected in FA3.

My "sh int atm0" is:

ATM0 is up, line protocol is up

Hardware is MPC ATMSAR (with Alcatel ADSL Module)

Description: *** INTERFACE OUTSIDE ***

MTU 4470 bytes, sub MTU 4470, BW 1124 Kbit, DLY 320 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ATM, loopback not set

Encapsulation(s): AAL5 AAL2, PVC mode

10 maximum active VCs, 64 VCs per VP, 1 current VCCs

VC Auto Creation Disabled.

VC idle disconnect time: 300 seconds

Last input 00:00:17, output 00:00:01, output hang never

Last clearing of "show interface" counters never

Input queue: 0/224/0/0 (size/max/drops/flushes); Total output drops: 2

Queueing strategy: Per VC Queueing

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 1000 bits/sec, 0 packets/sec

7151 packets input, 7256977 bytes, 0 no buffer

Received 12 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 186 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

6541 packets output, 1608045 bytes, 0 underruns

0 output errors, 0 collisions, 3 interface resets

0 output buffer failures, 0 output buffers swapped out

and: "sh atm pvc" is:

sh atm pvc

VCD / Peak Avg/Min Burst

Interface Name VPI VCI Type Encaps SC Kbps Kbps Cells Sts

0 3 0 35 PVC SNAP UBR 1124 UP

How I can attribute de public IP in my BVI1 or any other inteface to share internet from WIFI and LAN interfaces?

Have any idea?

Thanks in advance!

Giuseppe Larosa Sun, 08/03/2008 - 05:07
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Hello Ivan,

now you know that the ATM PVC is ok and you got a public IP address on your laptop.

My idea was to use fas3 just to have a LAN interface in bridge-group 1.

I'm afraid that BVI1 is not able to get an IP address via DHCP. A BVI exists to provide L3 services to a bridge-group in IRB.

However, try with shut/no shut of interface BVI1 to trigger a DHCP request

and see it it takes an ip address.

Hope to help


ivanmoreira1130 Sun, 08/03/2008 - 13:05
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Hi Giuseppe, after some hours trying a solution, finally I can configure the equipament to get public IP over interface BVI1 (config in attach). But now I can't access the internet. From CLI and my laptop I can ping the referred public IP obtained in interface BVI1, but any other public IP are possbile.

The differeces in configs are some chages made in ATM, VLAN and BVI interfaces.

Thanks in advance.


Giuseppe Larosa Sun, 08/03/2008 - 21:59
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Hello Ivan,

it sounds good

I've seen that you moved dhcp on an atm subif and you used RBE (atm route-bridged ip) that is usually used on NAS side (network side).

Now, you just need to move the nat outside command from BVI1 to atm 0.1 and change every reference to BVI1 in atm0.1 in order to have CBAC (ip inspect ) and NAT to work.

You have already done the most difficult part!

Hope to help


ivanmoreira1130 Mon, 08/04/2008 - 02:01
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Hello Giuseppe,

I proceeded to the changes in agreement your instructions and now through the CLI I can ping the public IP of router and the next node to the my ISP, using the command ping x.x.x.x source int BVI1, but any other public IP. Executing the same command however using option BVI2, I can only ping the public interface of router. About my laptop I can ping the Ip of the public interface of router too.



Giuseppe Larosa Mon, 08/04/2008 - 14:05
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Hello Ivan,

if the ip address is assigned to atm0.1 what is the role of BV1 ?

using BVI2 as a source can be a problem because it is a private ip address but on the router itself.

The test must be done from a PC connected on a port part of bridge-group 2

verify on the router with sh ip nat translations

that an entry is created for the private ip address of the PC.

BV1 should be useless if without an IP address your L3 public interface is the one that got the public ip address via DHCP : ATM0.1

If everything is ok you should be able to do web browsing on a PC on a fas N with N <> 3 or on the WIFI.

I wonder if the bridge-group 1 command under atm0.1 is still useful if all users are under bridge-group 2.

It may be time to remove BVI1 and bridge-group 1 from the configuration.

Hope to help


ivanmoreira1130 Mon, 08/04/2008 - 15:34
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Hi Giuseppe!

Since the last post, I've made progress. Now I can ping any public IP addres under CLI. Over my laptop I can only ping the public IP address of my router.

In attach you can see my actual config and a "debug Ip packet" I'm don't understand this :(

The public IP address are attribuited in interface BVI1. If a try ping with source BVI2, the ping did not respond.

Trying "sh ip transla" don't show anything in CLI.

I try too, eliminite BVI1 association with ATM0.1 but not get public IP.

Under the config in attach, my "sh ip bri" are:

ADSLGateway#sh ip int bri

Interface IP-Address OK? Method Status Protocol

FastEthernet0 unassigned YES unset up down

FastEthernet1 unassigned YES unset up down

FastEthernet2 unassigned YES unset up down

FastEthernet3 unassigned YES unset up up

Dot11Radio0 unassigned YES NVRAM up up

ATM0 unassigned YES NVRAM up up

ATM0.1 unassigned YES manual up up

Vlan1 unassigned YES NVRAM up up

NVI0 unassigned YES unset administratively down down

Vlan2 unassigned YES NVRAM administratively down down


BVI1 77.54.XXX.X YES DHCP up up

After your analysis please tell me exactly commands to insert in my router, because I'm very dummy user :)

Thanks, Thanks and Thanks again!!!

PS: Excuse for my English, I am Brazilian and English it is not my strong point!



Giuseppe Larosa Wed, 08/06/2008 - 13:48
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Hello Ivan,

I cannot open your last config file post it as a text file if you can

The PC is always connected to Fas3 ?

that is on bridge-group 1 --> BVI1

use a Fas port on bridge-group 2 in order to have NAT to start to work

connect your PC to Fas0 get a private ip address and then test.

Hope to help



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