Configuring a Cisco 877 Router for Be/O2 Broadband

This post is an amended version of this guide detailing how to set up a Cisco 877 router for BE Broadband or O2 Broadband in the UK. If you’d like to see the full config, just leave a comment and I’ll send it over.

This article covers the following router models:

  • CISCO877-K9 (Wired)
  • CISCO877W-G-A-K9
  • CISCO877W-G-E-K9
  • CISCO877W-G-J-K9

Before we begin, it’s important to point out that Be Broadband uses RFC1483 Bridge mode instead of PPPoA used my most UK ISPs. Additionally, they use PVC 0/101 instead of the standard 0/38.

Hardware Setup

Connect your PC with the router via a console attached to your router’s console port and PC’s serial port. Open a serial connection using Putty.


Once logged in, you’ll want to create a user so you can log in after copying your running-config to your startup-config at the end of this process.

username myusername privilege 15 secret 5 mypassword

Next, set up a local DHCP server (if required):

no ip dhcp use vrf connected
ip dhcp excluded-address
ip dhcp excluded-address
ip dhcp pool lanpool
   lease 0 2

Next, enable Integrated Routing and Bridging (IRB) on your router.

Enter the following command in global configuration mode:

bridge irb

Create your bridge:

bridge 1 protocol ieee
bridge 1 route ip

and configure IP:

interface BVI1
description my local range
ip address <-- Change as appropriate
ip nat inside
ip virtual-reassembly!

Link your local interfaces to the bridge:

interface Vlan1
no ip address
bridge-group 1

Configure DSL interface from global mode:

interface ATM0mac-address [MAC of original BeBox/o2 Router]
no ip address
no ip redirects
no ip unreachables
no ip proxy-arp
no atm ilmi-keepalive
dsl operating-mode auto
no shut
interface ATM0.1 point-to-point
description Link to BE/O2 Broadband
ip address 87.194.X.X <----- IP/Mask of Be/O2 Broadband
ip pim sparse-dense-mode
ip nat outside
ip virtual-reassembly
no snmp trap link-status
atm route-bridged ip
pvc 0/101
encapsulation aal5snap
oam-pvc manage

Configure routing and NAT:

create access-list
access-list 1 permit <-- Change as above
ip nat inside source list 1 interface ATM0.1 overload

setup your default route:

ip route <--- Change to details supplied by BE Broadband

To commit everything to your startup config, issue:

copy running-config startup-config


If you have problems, you can debug the ATM interface by issuing the following command:

debug atm event
debug atm errors

These combined with the usual show interface commands will give CRC and header error counts which can be useful.

Thanks for the tips, Sebastian @

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