topic Getting different broadcast ip in Operating System - Linux

Getting different broadcast ip

monu_1 — Fri, 07 Nov 2008 06:38:36 GMT

Hi All,

When i config eth port, it's getting different broadcast ip. Pl see below output-

# ifconfig eth1 10.232.168.111 netmask 255.255.255.0 up

eth1 Link encap:Ethernet HWaddr 00:04:5A:46:99:51
inet addr:10.232.168.111 Bcast:10.255.255.255 Mask:255.255.255.0
inet6 addr: fe80::204:5aff:fe46:9951/64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:31 dropped:0 overruns:0 carrier:62
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:11 Base address:0x8000

Broadcast ip should be 10.232.168.255

kernel version is 2.6.10

Please comment on this.

Thanks,
-MKS

Re: Getting different broadcast ip

Johnson Punniyalingam — Wed, 12 Nov 2008 08:13:55 GMT

Hi ,

Please edit this file add entry for your broadcast ip

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

Example:-
==========
DEVICE=eth1
BOOTPROTO=none
BROADCAST=10.8.48.255 --> you can change Broadcast ip address
HWADDR=00:09:6B:B5:36:DA
IPADDR=10.232.168.111
NETMASK=255.255.255.0
NETWORK=10.8.4.0
ONBOOT=yes
GATEWAY=10.232.168.0
TYPE=Ethernet

after that stop and start "

/etc/rc.d/init.d/network restart

Thanks,
Johnson

Re: Getting different broadcast ip

Ivan Ferreira — Wed, 12 Nov 2008 12:51:56 GMT

I just tested on a Linux kernel 2.6.18-92.el5.

# ifconfig eth0:1 10.232.168.111 netmask 255.255.255.0 up
# ifconfig eth0:1
eth0:1 Link encap:Ethernet HWaddr 00:0C:29:8A:24:2A
inet addr:10.232.168.111 Bcast:10.232.168.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:177 Base address:0x1400

The result is correct.

Re: Getting different broadcast ip

Fredrik.eriksson — Thu, 13 Nov 2008 08:23:50 GMT

# ifconfig eth1 10.232.168.111 netmask 255.255.255.0 broadcast 10.232.168.255

This will do the job, but if you want it to stick after next reboot i'd suggest the above method :)

ps. the "up" at the end is not needed when you're setting an address, the interface will be automagically up'd when you set an IP ds.

Best regards
Fredrik Eriksson