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Harel
Asked: 2011-01-28 08:23:06 +0800 CST

2 servers cannot see each other in internal subnet (192.168.1.10)

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I have a few servers in one rack. They all have 2 network interfaces eth0 and eth1. On all, eth0 has a public IP address assigned which works well. I'm setting up a private subnet on the second eth1 interface, but no matter what I do, the servers can't seem to see each other if i ping them on the 192.168.1.* range. Thanks in advance, Harel

Using 2 servers as an example, neither can ping/ssh eachother via the 192 range:

Server 1:

eth1      Link encap:Ethernet  HWaddr 00:26:b9:76:9d:43  
      inet addr:192.168.1.5  Bcast:192.168.1.255  Mask:255.255.255.0
      UP BROADCAST MULTICAST  MTU:1500  Metric:1
      RX packets:0 errors:0 dropped:0 overruns:0 frame:0
      TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000 
      RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
      Interrupt:17 Memory:dc000000-dc012100 


spiderman:/home/harel# ip route show
X.X.X.X/29 dev eth0  proto kernel  scope link  src X.X.X.X 
192.168.1.0/24 dev eth1  proto kernel  scope link  src 192.168.1.5 
default via X.X.X.X dev eth0

Server 2:

eth1      Link encap:Ethernet  HWaddr b8:ac:6f:8a:78:fd  
          inet addr:192.168.1.10  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:17 Memory:dc000000-dc012100 

hulk:/home/harel# ip route show
X.X.X.X/29 dev eth0  proto kernel  scope link  src X.X.X.X
192.168.1.0/24 dev eth1  proto kernel  scope link  src 192.168.1.10 
default via X.X.X.X dev eth0

Obiously the public ips above are masked as X.X.X.X

There are no iptables rules defined on any server:

hulk:/home/harel# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
linux ip configuration ethernet subnet

4 Answers

  1. Best Answer

    It sounds like your datacenter people are isolating each server/port. Let them know what you want to do :-)

    • 1

  2. Do you control the switch which the eth1 interfaces are connected to? It's possible there could be filtering happening there.

    • 0

  3. Try connecting the eth1 ports on the two servers directly to each other with a crossover cable, to rule out other problems on the network. If it still doesn't work, you may have faulty hardware somewhere.

    • 0

  4. The problem was the wiring to the switch. It has been rewired and now works great. Thanks for all the help.

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