VYATTA - The Easy Tutorial - Case Study 10

Vyatta Case 10 - Bridging
Last Change : Dec 26 2007

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Details What is Vyatta?
Screenshots
Prerequisites
Tutorial Vyatta
Vyatta & Cisco Commands
Vyatta/Cisco/Quagga Comparison (Quagga section)
Case Study 1 - Static routes (VC 2.0)
Case Study 2 - OSPF simple (VC 2.0)
Case Study 3 - OSPF advanced (VC 2.0)
Case Study 4 - BGP (VC 3.0)
Case Study 5 - VRRP (VC 2.2)
Case Study 6 - NAT (VC 2.0)
Case Study 7 - DHCP (VC 2.2)
Case Study 8 - IPSec (VC 2.2)
Case Study 9 - Packages (VC 3.0)
Case Study 10 - Bridging (VC 3.0)
Case Study 11 - CDP VC 3.0

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1. CASE PRINCIPLE 2. PICTURE 3. CONFIGURATIONS 4. SHOW COMMANDS

Vyatta version used: VC 3.0 Oct 29, 2007
1. CASE PRINCIPLE

Network bridges connects multiple network segments or local area networks at the data link layer (layer 2) of the OSI model.
The behavior of bridges are very similar to hubs or switches, they all let layer two broadcasts pass through them.
As a comparison, routers work at the layer three of the OSI model and will stop these broadcasts.

In our case study, we will bridge two network interfaces on three different components: a Vyatta router, a Cisco router and a Linux machine. (The windows XP bridging howto will come very soon).

An IP address is set on the bridges to be able to manage them:
On Vyatta, as this is not possible to do it from the router interface, you must do it at the Linux level.
On Cisco, you must activate the integrated routing and bridging (IRB) mode.

2. PICTURE

Functionalities tested:

(click on the web links to have more details about a protocol)

Interface settings
bridging

case study bridge vyatta case study bridge cisco case study bridge linux

3. CONFIGURATIONS

VYATTA ROUTER VC3.0 Oct 29, 2007
CISCO ROUTER 2621 IOS: 12.2(23a)

edit interfaces ethernet eth0
  set bridge-group bridge br0 interface FastEthernet0/0
  bridge-group 1

edit interfaces ethernet eth1
  set bridge-group bridge br0 interface FastEthernet0/1
  bridge-group 1

set system host-name Vyatta-Router hostname Cisco-router

set service telnet
line vty 0 4
  no login

bridge irb
bridge 1 protocol ieee
bridge 1 route ip

interface BVI 1
  ip address 10.0.2.1

Configurations done at the
Debian/Linux level:
Login with the root user.
Set the bridge IP address:

#ifconfig br0 10.0.2.1 netmask 255.255.255.0
To keep your settings permanently:

#vim /etc/network/interfaces

auto br0
iface br0 inet static
address 10.0.2.1
netmask 255.255.255.0

LINUX Debian or Ubuntu

- Install the tools need to build a bridge:

#apt-get install bridge-utils
- Load the bridge kernel module:

#modprobe bridge
- Check that the bridge module is loaded:

#lsmod | grep bridge
- Activate the Ethernet interfaces:

#ifconfig eth0 up
#ifconfig eth1 up
- Create the bridge:

#brctl addbr br0
- Add members to the bridge:

#brctl addif br0 eth0
#brctl addif br0 eth1
- Set the bridge IP address:

#ifconfig br0 10.0.2.1 netmask 255.255.255.0
To keep your settings after a reboot, create the following script stored in the "/root/bridge.sh" file:

#!bin/bash
# Load the bridge kernel module
modprobe bridge
# Activate the Ethernet interfaces
ifconfig eth0 up
ifconfig eth1 up
# Create the bridge
brctl addbr br0
# Add members to the bridge
brctl addif br0 eth0
brctl addif br0 eth1
# Set the bridge IP address:
ifconfig br0 10.0.2.1 netmask 255.255.255.0
Then you have to add the following lines in the "/etc/crontab" file:

#vim /etc/crontab

@reboot root /root/bridge.sh

4. SHOW COMMANDS:

Vyatta Router

- Check the bridge status:

Vyatta-Router#show bridge

bridge name bridge id STP enabled interfaces

br0 8000.0000ab12cd34 no eth0

eth1

The bridge ID begins with "8000" and is followed by the lowest MAC address of one of its members.

- Check the bridge members:

Vyatta-Router#show bridge br0 macs

port no mac addr is local? ageing timer

2 00:00:ab:12:cd:34 yes 0.00

1 00:04:11:22:33:44 yes 0.00

- Check the bridge interface:

vyatta:~#ifconfig br0
Cisco Router

- Check the bridge members:

#show interface irb
- Check the bridge interface:

#show interface BVI1
Linux Router

- Check the bridge status:

Linux#brctl show

bridge name bridge id STP enabled interfaces

br0 8000.0000ab12cd34 no eth0

eth1

The bridge ID begins with "8000" and is followed by the lowest MAC address of one of its members.

- Check the bridge members:

Linux#brctl showmacs br0

port no mac addr is local? ageing timer

2 00:00:ab:12:cd:34 yes 0.00

1 00:04:11:22:33:44 yes 0.00

- Check the bridge interface:

Linux#ifconfig br0

VYATTA ROUTER VC3.0 Oct 29, 2007	CISCO ROUTER 2621 IOS: 12.2(23a)
edit interfaces ethernet eth0 set bridge-group bridge br0	interface FastEthernet0/0 bridge-group 1
edit interfaces ethernet eth1 set bridge-group bridge br0	interface FastEthernet0/1 bridge-group 1
set system host-name Vyatta-Router	hostname Cisco-router
set service telnet	line vty 0 4 no login
	bridge irb bridge 1 protocol ieee bridge 1 route ip
	interface BVI 1 ip address 10.0.2.1

bridge name	bridge id	STP enabled	interfaces
br0	8000.0000ab12cd34	no	eth0
			eth1

port	no	mac addr	is local?	ageing timer
2		00:00:ab:12:cd:34	yes	0.00
1		00:04:11:22:33:44	yes	0.00