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Ethan Brouwer
Asked: 2015-09-15 13:06:30 +0800 CST

Local Network not working on one server while the other one works fine

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So I have two servers (davros - working, kraken - not working) on the same subnet (10.10.28.0/24). They both have the same configurations and yet only one of them works. (Also, I should note that they're both VMS on the same KVM instance running Ubuntu 14.04.

To start, here are each of their /etc/network/interfaces files:

# Davros (Working one)

# Interface eth0
auto eth0
iface eth0 inet static
    address <davros_ip_addr>
    netmask 255.255.255.192
    network 192.41.71.192
    broadcast 192.41.71.255
    gateway 192.41.71.193

# Interface eth1
auto eth1
iface eth1 inet static
    address 10.10.28.1
    netmask 255.255.0.0
    network 10.10.0.0
    broadcast 10.10.255.255

and

# Kraken (Broken one)

# Interface eth0
auto eth0
iface eth0 inet static
    address <kraken_ip_addr>
    netmask 255.255.255.192
    network 192.41.71.192
    broadcast 192.41.71.255
    gateway 192.41.71.193

# Interface eth1
auto eth1
iface eth1 inet static
    address 10.10.28.2
    netmask 255.255.0.0
    network 10.10.0.0
    broadcast 10.10.255.255

If you were to diff them, the only thing that's different is their ip addresses.

Next, here's the output of ip addr on both:

# Davros (Working one)

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 52:54:00:87:86:32 brd ff:ff:ff:ff:ff:ff
    inet <davros_ip_addr>/26 brd 192.41.71.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:fe87:8632/64 scope link 
       valid_lft forever preferred_lft forever
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 52:54:00:13:9d:ad brd ff:ff:ff:ff:ff:ff
    inet 10.10.28.1/16 brd 10.10.255.255 scope global eth1
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:fe13:9dad/64 scope link 
       valid_lft forever preferred_lft forever

and

# Kraken (Broken one)

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 52:54:00:19:c0:ae brd ff:ff:ff:ff:ff:ff
    inet <kraken_ip_addr>/26 brd 192.41.71.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:fe19:c0ae/64 scope link 
       valid_lft forever preferred_lft forever
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 52:54:00:eb:ef:92 brd ff:ff:ff:ff:ff:ff
    inet 10.10.28.2/16 brd 10.10.255.255 scope global eth1
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:feeb:ef92/64 scope link 
       valid_lft forever preferred_lft forever

Once again, a diff would only show differences in the actual ip addresses.

Here's my route -n output (which is the same on both):

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.41.71.193   0.0.0.0         UG    0      0        0 eth0
10.10.0.0       0.0.0.0         255.255.0.0     U     0      0        0 eth1
192.41.71.192   0.0.0.0         255.255.255.192 U     0      0        0 eth0

Another thing to clarify, the external network works perfectly fine on both of them. I can ping 8.8.8.8 with no problems. It's just when I try to ping on the local network that kraken (the broken one) fails where davros doesn't.

I've looked all over the place for how to best diagnose this and finally decided I had to ask here. I've been working on this for hours on end. If you need any more information at all, or if you want me to run a command and post the output, please do not hesitate to ask at all. Or clarification. I have no idea what could be causing this. Thank you in advance for any help you give.

ubuntu

0 Answers