Connection between VMs does not work

Connection between VMs does not work

This section describes how to troubleshoot the connectivity issues between VMs.

In this section, the following example of communication between VM_1 and VM_2 is described:

../../../../_images/011_01.png

To troubleshoot the connection between VMs:

  1. Log in to an OpenStack compute node. For example, cmp002.

  2. Verify the flow between VMs. For example:

    flow -l | grep '192.168.0.5\|192.168.0.100'
    

    Example of system response:

    Index                Source:Port/Destination:Port                      Proto(V)
    --------------------------------------------------------------------------------
    492152<=>1500364      192.168.0.5:792                                     1 (5)
                          192.168.0.100:0
    (Gen: 1, K(nh):83, Action:F, Flags:, QOS:-1, S(nh):83,  Stats:487/519142,
    
    
    1500364<=>492152      192.168.0.100:792                                   1 (5)
                          192.168.0.5:0
    (Gen: 1, K(nh):83, Action:F, Flags:, QOS:-1, S(nh):35,  Stats:487/519142,
    
  3. Use the output from the previous step to get the information on VRF by ID. For example, for S(nh):83 and S(nh):35:

    nh --get 83
    
    Id:83         Type:Encap          Fmly: AF_INET  Rid:0  Ref_cnt:4          Vrf:5
                  Flags:Valid, Policy,
                  EncapFmly:0806 Oif:8 Len:14
                  Encap Data: 02 29 64 b3 e2 f4 00 00 5e 00 01 00 08 00
    
    nh --get 35
    
    Id:35         Type:Tunnel         Fmly: AF_INET  Rid:0  Ref_cnt:4850       Vrf:0
                  Flags:Valid, MPLSoUDP,
                  Oif:0 Len:14 Flags Valid, MPLSoUDP,  Data:0c c4 7a 50 27 88 0c c4 7a 17 99 5d 08 00
                  Vrf:0  Sip:10.167.4.102  Dip:10.167.4.103
    
  4. Verify the routing table for VRF (routing instance). For example:

    rt --dump 5 | grep 192.168.0.5/32
    

    Example of system response:

    192.168.0.5/32       32       P       -       83       2:29:64:b3:e2:f4(240568)
    
    rt --dump 5 | grep 192.168.0.100/32
    

    Example of system response:

    192.168.0.100/32       32       LP       44       35       2:d1:32:42:b5:87(149684)
    

If the above procedure does not resolve the connectivity issue, proceed with the following steps:

  1. Verify that a network policy is created using the OpenContrail web UI in Configure > Networking > Policies.

  2. Verify that a network policy is assigned to virtual networks (VNs) using OpenContrail web UI in Configure > Networking > Network > Edit Network > Network Policy(s).

  3. Verify the rules of security group(s).

  4. Verify that VNs are assigned to a correct security group.

  5. Verify whether the prefixes were exchanged in the routing table using the rt --dump <VRF_ID> command.

  6. Verify MTU on a physical interface used by vRouter.

  7. Verify the MTU jumbo frames in the underlay network.