Cisco Nexus 1000VE for VMware vSphere Troubleshooting Guide, Release 5.2(1)SV5(1.1)

Viewing Ports from the VSE

The Cisco Nexus1000VE differentiates between virtual and physical ports on each of the VSEs. Figure 10-1 shows how ports on the Cisco Nexus1000VE switch are bound to physical and virtual VMware ports within a VSE.

Figure 10-1 VSE View of Ports

On the virtual side of the switch, three layers of ports are mapped together:

• Virtual NICs—Three types of Virtual NICs are in VMware. The virtual NIC (vnic) is part of the VM and represents the physical port of the host that is plugged into the switch. The virtual kernel NIC (VTEP) is used by the hypervisor for management, VMotion, iSCSI, network file system (NFS), and other network access needed by the kernel. This interface carries the IP address of the hypervisor itself and is also bound to a virtual Ethernet port. The vswif (not shown) appears only in CoS-based systems and is used as the VMware management port. Each type maps to a virtual Ethernet port within the Cisco Nexus1000VE.
• Virtual Ethernet Ports (VEth)—A vEth port is a port on the Cisco Nexus 1000V. The Cisco Nexus 1000V has a flat space of vEth ports 0..N. The virtual cable plugs into these vEth ports that are moved to the host running the VM.

Virtual Ethernet ports are assigned to port groups.

• Local Virtual Ethernet Ports (lveth)—Each host has a number of local vEth ports. These ports are dynamically selected for vEth ports that are needed on the host.

These local ports do not move and are addressable by the module/port number method.

On the physical side of the switch, from bottom to top, is the following:

• Each physical NIC in VMware is represented by an interface called a vmnic. The vmnic number is allocated during VMware installation, or when a new physical NIC is installed, and remains the same for the life of the host.

Viewing Ports from the VSM

Figure 10-2 shows the VSM view ports.

Figure 10-2 VSM View of Ports

Port Types

The following types of ports are available:

• vEths can be associated with any one of the following:

– VNICs of a Virtual Machine on the ESX host.

– VTEPs of the ESX Host

– VSWIFs of an ESX COS Host.

• Eths (physical Ethernet interfaces)—Correspond to the outside-trunk interface of the VSEs.

For more information about Layer 2 switching, see the Cisco Nexus 1000VE Layer 2 Switching Configuration Guide .

Verifying a Connection Between VSE Ports

You can verify a connection between two vEth ports on a VSE.

Step 1 View the state of the VLANs associated with the port. If the VLAN associated with a port is not active, the port may be down. In this case, you must create the VLAN and activate it.

switch# show vlan v lan-id

Step 2 View the state of the ports on the VSM.

switch# show interface brief

Step 3 Display the ports that are present on the VSE, their local interface indices, VLAN, type (physical or virtual), port mode and port name.

switch# module vse module-number execute vemcmd show port

The key things to look for in the output are as follows:

• State of the port.
• CBL.
• Mode.
• Attached device name.
• The LTL of the port that you are trying to troubleshoot. It will help you to identify the interface quickly in other VSE commands where the interface name is not displayed.
• Make sure that the state of the port is up. If not, verify the configuration of the port on the VSM.

Step 4 View the VLANs and port lists on a particular VSE.

switch# module vse module-number execute vemcmd show bd

If you are trying to verify that a port belongs to a particular VLAN, make sure that you see the port name or LTL in the port list of that VLAN.

Verifying a Connection Between VSEs

You can verify a connection between vEth ports on two separate VSEs.

Step 1 Log in to the upstream switch and make sure that the port is configured to allow the VLAN that you are looking for.

As this output shows, VLANs 1,60-69, 231-233 are allowed on the port. If a particular VLAN is not in the allowed VLAN list, make sure to add it to the allowed VLAN list of the port.

Isolating Traffic Interruptions

You can isolate the cause for no traffic passing across VMs on different VSEs.

Step 1 Inside the VM, verify that the Ethernet interface is up.

ifconfig –a

If not, delete that NIC from the VM, and add another NIC.

Step 2 Using any sniffer tool, verify that ARP requests and responses are received on the VM interface.

Step 3 On the upstream switch, look for the association between the IP and MAC address:

debug arp
show arp

Step 4 You have completed this procedure.

Limitations and Restrictions

A syslog is generated if one of the following configurations exists when you try to disable automatic static MAC learning for MS-NLB because they do not support this feature:

• PVLAN port
• Ports configured with unknown unicast flood blocking (UUFB)

Disabling Automatic Static MAC Learning on a vEthernet Interface

You must disable automatic static MAC learning before you can successfully configure NLB on a vEthernet (vEth) interface.

In interface configuration mode enter the following commands:

In port profile configuration mode enter the following commands:

Checking Status on a VSM

If the NLB unicast mode configuration does not function, check the status of the Virtual Supervisor Module (VSM).

Confirm that the no mac auto-static-learn command is listed in the vEth and/or port profile configurations.

Step 1 In interface configuration mode, generate the VSM status.

Step 2 In port profile configuration mode, generate the VSM status.

Checking the Status on a VSE

If the NLB unicast mode configuration does not function, check the status of the Virtual Ethernet Module (VSE). Check the following:

• Confirm that the MS-NLB vEths are disabled.
• Confirm that the MS-NLB shared-MAC (starting with 02:BF) is not listed in the Layer 2 (L2) MAC table.

Step 1 Generate the VSE status.

Step 2 Generate the Layer 2 MAC address table for VLAN 59.

Bridge domain 15 brtmax 4096, brtcnt 6, timeout 300

VLAN 59, swbd 59, ""

Flags: P - PVLAN S - Secure D - Drop