Ping goes down after enabling eth1

drpaudel · 07-18-2016, 01:47 AM

My Scenario, I am using Centos7.2.
in eth0: 000.000.253.91 (I am using Public IP, sorry I am replacing first 2 block with 0s for security reasons)
in eth1: 192.168.1.179

When I make eth1 is down, only public network work fine. But when I enable eth1, ping stops. After ssh remotely, it again starts. for eth1 I have no gateway and dns. Used Ips are not used anywhere.
What could be the issue.

Here is eth0

Quote:

TYPE="Ethernet"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
NAME="eth0"
UUID="9feadbbc-8f37-4df4-a67e-81d727e82094"
DEVICE="eth0"
ONBOOT="yes"
DNS1="000.000.000.38"
DNS2="000.000.000.38"
IPADDR="000.000.253.91"
PREFIX="29"
GATEWAY="000.000.253.89"
IPV6_PEERDNS="yes"
IPV6_PEERROUTES="yes"
IPV6_PRIVACY="no"

Here is eth1

Quote:

TYPE=Ethernet
BOOTPROTO=none
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
NAME=eth1
UUID=0e66387c-5431-4a61-84f5-a0fcad210719
DEVICE=eth1
ONBOOT=yes
IPADDR=192.168.1.169
PREFIX=24
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes
IPV6_PRIVACY=no

jpollard · 07-18-2016, 07:07 AM

When it fails check the routing tables (route -n) and make sure the default gateway hasn't been removed (or switched to eth1). I think it has been, and since eth1 doesn't have a gateway, the pings quit.

Remove/comment out the line "DEFROUTE=yes"

To recover, just take eth0 and eth1 down and bring up eth0, Verify that the default route is working.

then bring up eth1 up and see that the default route is still correct.