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:

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.