NIC Bonding In Linux

Nic bonding is defined as bonding of two or more network cards on a server/pc to form a parallel single connection. This is a great way of achieving redundancy to a server if its having more number of network cards. Its having many names like.

1. Link aggregation
2. Channel Bonding
3. NIC Bonding
4. NIC teaming
5. Network card Bonding
6. Ethernet bonding
7. Trunking
8. Etherchannel
9. Multi-link truning(MLT)
10.Network bonding
11.Network Fault Tolerance(NFT)
12.Port channel
13.Smartgroup
14.EtherTrunk

Nic bonding is used to provide two benefits for us

1. High bandwidth
2. Redundancy/resilience

Before Clustering softwares come in to existing this technique is widely used to provide redundancy to a high end server. After cluster software introduced its used to enhance the cluster redundancy.

In this post we will see how can we achieve Nic bonding.
Nic bonding will work with the help of bonding driver in kernel.

Implementing NIC bonding : Participating interfaces.

eth0

eth1

bnd0

Step1 : Create bond interface file with following content in it

vi /etc/syconfig/network-scripts/ifcfg-bnd0

DEVICE=bnd0

IPADDR=192.168.0.234

NETWORK=192.168.0.0

NETMASK=255.255.255.0

USERCTL=no

BOOTPROTO=none

ONBOOT=yes

GATEWAY=192.168.0.1

save and exit the file

Step2 : Now create a bnd0 virtual interface in modprobe.conf as shown below

alias bnd0 bonding

options bnd0 miimon=100 mode=6

Save and exit the file

Let me explain what actually the above two lines indicates

Line1 : (alias bnd0 bonding) to load the bonding module in to kernel

Line2 : Indicate the option for thie bond interface

miimon is nothing but to MONitor with MIItool to check the availability of other interfaces.

mode is to specify whether the bond is configured as load balancing or fail over. Here its load-balancing which means data transmission will be shared between two interfaces. To know more about modes click here

Step3 : Load the module in to kernel with modprob command to update this changes to kernel

#modprob bonding

Step4 : edit interface card details of both physical devices

For eth0

vi /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0

USERCTL=no

ONBOOT=yes

MASTER=bnd0

SLAVE=yes

BOOTPROTO=none

For eth1

vi /etc/sysconfig/network-scripts/ifcfg-eth1

DEVICE=eth1

USERCTL=no

ONBOOT=yes

MASTER=bnd0

SLAVE=yes

BOOTPROTO=none

Save and exit the files

The above thing is self explanatory for many admins but let me explain to new people.

DEVICE Indicates what is the device name

USERCTL Indicates that can user control this device(here its no)

ONBOOT Indicates that at the boot time do this device should be up?

MASTER Is this device has master? Then what it is(here its bnd0)

SLAVE Is this device acting as slave?

BOOTPROTO What about getting ip add from what protocol?(its set to none which indicate its a static IP)

Step5 : Restart the network service and see the output of ifconfig for your self.

#service network restart

#ifconfig

Questions & Answers

1. How can we say my data is flowing in which path?

Ans : Link aggregation(bonding driver) will take care of sending all the frames of particular session in same path. This is called as ordering of frames.

2. Can we bond more than 2 NIC?

Ans : Yes we can, follow the same procedure. In fact there is no limit but linux server do have limit to have total number of NIC cards.

Tips on implementing NIC bonding

1. Enable spanning tree for switches, with out which network speed reduces.

2. Be careful if you’re doing this over a remote ssh.

Like the post? Please Subscribe to free RSS feed to get updates

Failed To Make Swap Directory Cache (13) Permission Denied

When installing squid as cache server you have to create cache folder with “squid -z” command with out quotes. But when you are trying this you will see

/usr/local/squid/sbin# ./squid -z
2010/04/29 22:39:16
Creating Swap Directories

FATAL : Failed to make swap directory /usr/local/squid/var/cache: (13) Permission denied

Squid Cache (Version 2.5.STABLE5) : Terminated abnormally.

CPU Usage : 0.000 seconds = 0.000 user + 0.000 sys

This is due to that /usr/local/squid/var/cache folder is not owned by effective user. To resolve this issue follow below steps

Step1 : Create squid user(A normal user) if the squid user is not there

#useradd squid

Step2 : Specify the effective user entry in squid.conf file with squid as username by editing it.

#vi /usr/local/squid/etc/squid.conf

change the entry from

# cache_effective_user nouser

to

cache_effective_user squid

Save the file now

Step3 : Now change the ownership of the cache folder to squid user

#chown -R squid.squid /usr/local/squid/var/cache

Step4 : Now create cache directory with squid -z command

#squid -z

Now you will be out of issue.

Like the post? Please Subscribe to free RSS feed to get updates

How To Change The Date In Linux?

How can we change the date/time in linux?
Ans : Changing date in linux is bit confusing. If you want to change date in GUI its very much easy and if you want to change it when it comes to CLI its bit hard to remember it.

Date is the command to check whats the present date
#date

To change the date use below command
#date MMDDHHMMYYYY.ss

MM => Two digit month value

DD => Two digit day value

HH => Two digit hour value

MM => Two digit minuite value

YYYY => Four digit year value

ss => Two digit seconds value(very rare we will be using this)

Example1 : I want to change the date to Nov 24 1:36 PM 2010

#date 112413362010

Example2 : I want to change the date to Jan 9th 8:05.04 AM 2010

#date 010908052010.04

Now the date will be changed to your required date.

Like the post? Please Subscribe to free RSS feed to get updates

How To Set A PHP Path In Linux?

How can we set PHP path in linux?
Ans : When you install PHP and host some .php files on webserver your web server will not detect it. This is because your Apache server does not know how to interprit PHP files? And and where is php located? To eleminate this issue we have to set the php path in main php configuration file php.ini located in your machine. As the linux is open source and the location of this file differs from different flavors, so better option is to search for php.ini file as shown below.

find / -iname php.ini

or some common locations for Redhat and Ubuntu are shown below

For Redhat flavors

/etc/php.ini

For Ubuntu Flavors

/etc/php5/apache2/php.ini

To search for include_path and uncomment that before changes.

;include_path = ".:/usr/share/php"

After changes.

include_path = ".:/usr/share/php"

Now save and exit the file. And you have to restart the apache server to detect this settings.

For Redhat

#service httpd restart

For Ubuntu

/etc/init.d/apache2 restart

Now start coding in PHP and enjoy the php scripting.

Like the post? Please Subscribe to free RSS feed to get updates