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Grumpy
Asked: 2013-06-03 15:29:05 +0800 CST

Unable to discover other systems in lan - centos 6.4

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I have 4 servers, 3 old and 1 new, and each of them are connected via vlan through eth0 and eth1 is used for internet.

Three of the servers are working fine and able to communicate with each other. However, the 4th server I just got doesn't seem to be able to discover other systems in the vlan and same with other 3 systems not able to see the newly installed server. The host confirms that it is connected to the same vlan.

For example, if I do arp from a working server (as in one of the original 3), it shows:

# arp
Address                  HWtype  HWaddress           Flags Mask            Iface
169.34.255.149.static.s  ether   00:18:74:92:39:00   C                     eth1
192.168.1.1              ether   00:25:90:66:24:fa   C                     eth0
192.168.1.2              ether   00:25:90:50:1e:f3   C                     eth0

But from the new 4th server, it shows only one entry:

# arp
Address                  HWtype  HWaddress           Flags Mask            Iface
169.34.255.149.static.s  ether   00:18:74:92:39:00   C                     eth1

All outputs from ifconfig seems identical to other servers and I don't see anything wrong with it. 

# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:25:90:26:38:59
          inet addr:192.168.1.4  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::225:90ff:fe26:3859/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:97 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 b)  TX bytes:7818 (7.6 KiB)
          Interrupt:20 Memory:fba00000-fba20000

eth1      Link encap:Ethernet  HWaddr 00:25:90:26:38:58
          inet addr:149.255.34.173  Bcast:149.255.34.175  Mask:255.255.255.248
          inet6 addr: fe80::225:90ff:fe26:3858/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:62738 errors:0 dropped:0 overruns:0 frame:0
          TX packets:39347 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:79312114 (75.6 MiB)  TX bytes:3356241 (3.2 MiB)
          Interrupt:16 Memory:fb900000-fb920000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:16 errors:0 dropped:0 overruns:0 frame:0
          TX packets:16 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:2792 (2.7 KiB)  TX bytes:2792 (2.7 KiB)

I feel like I'm missing something obvious as to why it's not working.

And here is my configuration on eth0

# cat ifcfg-eth0
DEVICE=eth0
HWADDR=00:25:90:26:38:59
TYPE=Ethernet
UUID=062b17d6-5555-496c-8259-03eaa5577883
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=none
IPADDR=192.168.1.4
NETMASK=255.255.255.0
IPV6INIT=no
IPV6_AUTOCONF=no
USERCTL=no
VLAN=yes # I tried this with and without it.
networking

1 Answers

  1. you can see your port eth0 doesn't receive any packet nor frame from the ifconfig command output:

    RX packets:0 errors:0 dropped:0 overruns:0 frame:0

    So it seems the VLAN tag is not specified in the switch port that connects to the eth0 of this machine. or you should see something on eth0 RX attributes.

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