CODEWITHSUNDEEP
network-programmingroutesexternalopenstackopenstack-neutron
Johnny
Johnny

Reputation: 11

No route to host for the C-class external IP only

The launched VM instance on the compute node can access all the external internet websites except the C-Class IPs. The controller and compute nodes had been installed successfully according to the openstack liberty guide on ubuntu.

[root@vm3 ~]# wget http://www.sina.com.cn Resolving www.sina.com.cn... 202.108.33.60 Connecting to www.sina.com.cn|202.108.33.60|:80... failed: No route to host.

However, both A-CLass and B-Class external IP can be accessed successfully:

 [root@vm3 ~]# wget http://www.163.com
    Resolving www.163.com... 60.207.246.98, 124.202.166.57
    Connecting to www.163.com|60.207.246.98|:80... connected.
    HTTP request sent, awaiting response... 200 OK
    Length: unspecified [text/html]
    Saving to: “index.html.1”

The VM's interfaces are:

[root@vm3 ~]# ifconfig eth1 Link encap:Ethernet HWaddr FA:16:3E:57:1B:57
inet addr:192.168.0.215 Bcast:255.255.255.255 Mask:192.0.0.0 inet6 addr: fe80::f816:3eff:fe57:1b57/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1450 Metric:1 RX packets:46213 errors:0 dropped:0 overruns:0 frame:0 TX packets:42118 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:13492902 (12.8 MiB) TX bytes:39875879 (38.0 MiB)

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:58630 errors:0 dropped:0 overruns:0 frame:0
          TX packets:58630 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:44931488 (42.8 MiB)  TX bytes:44931488 (42.8 MiB)

virbr0    Link encap:Ethernet  HWaddr 52:54:00:D2:F5:28  
          inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0
          UP BROADCAST RUNNING 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:0 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

Routes on VM are:

 [root@vm3 ~]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    169.254.169.254 192.168.0.200   255.255.255.255 UGH   0      0        0 eth1
    192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0
    192.0.0.0       0.0.0.0         192.0.0.0       U     1      0        0 eth1
    0.0.0.0         192.168.0.1     0.0.0.0         UG    0      0        0 eth1

I created the public network with which the VM is launched. The public network is 192.168.0.0/24 and private is 10.0.0.0/24. controller: 192.168.0.12/10.0.0.11 compute: 192.168.0.10/10.0.0.31

If I add the route for 202.108.33.60 explicitly, wget can work:

route add 202.108.33.60 gw 192.168.0.1

    [root@vm3 ~]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    202.108.33.60   192.168.0.1     255.255.255.255 UGH   0      0        0 eth1
    169.254.169.254 192.168.0.200   255.255.255.255 UGH   0      0        0 eth1
    192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0
    192.0.0.0       0.0.0.0         192.0.0.0       U     1      0        0 eth1
    0.0.0.0         192.168.0.1     0.0.0.0         UG    0      0        0 eth1

Does anybody know the cause or give some help on how to debug this problem? Thanks a lot!

Upvotes: 1

Views: 427

Answers (1)

Johnny
Johnny

Reputation: 11

After several days' analysis and digging, eventually I found the cause is the route entry "192.0.0.0 0.0.0.0 192.0.0.0 U 1 0 0 eth1" which will filter all the C-Class IPs as the LAN(neighbor network) and occasionally www.sina.com.cn is such a host. After I changed it to be as below, www.sina.com.cn can be accessed.

192.0.0.0 0.0.0.0 255.0.0.0 U 1 0 0 eth1

Upvotes: 0

Related Questions