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VMware: ESX Network Troubleshooting With Cisco

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The first VM server that I was re-IPing was not coming up.  Each server has 6 network ports separated by ISCSI and regular LAN traffic.  When I looked at the virtual switch configuration using “esxcfg-vswitch -l” if got the following:

# esxcfg-vswitch -l
Switch Name    Num Ports   Used Ports  Configured Ports  MTU     Uplinks
vSwitch0 64          6           64                1500    vmnic4,vmnic3,vmnic2,vmnic0

PortGroup Name      VLAN ID  Used Ports  Uplinks
Reg Network          0        0           vmnic0,vmnic2,vmnic3,vmnic4
Service Console     0        1           vmnic0,vmnic2,vmnic3,vmnic4

Switch Name    Num Ports   Used Ports  Configured Ports  MTU     Uplinks
vSwitch1       64          6           64                1500    vmnic5,vmnic1

PortGroup Name      VLAN ID  Used Ports  Uplinks
Service Console   2   0        1          vmnic1,vmnic5
ISCSI VLAN          0        1                vmnic1,vmnic5

Switch Name    Num Ports   Used Ports  Configured Ports  MTU     Uplinks
vSwitch2       64          1           64                1500

PortGroup Name      VLAN ID  Used Ports  Uplinks
Internal Switch     0        0

The switch having the issue was vSwitch0.  I started to remove the vmnics out of vSwitch0 setup as follows:

esxcfg-vswitch -U vmnic4 vSwitch0

This removed only vmnic4 from the switch.  Once this was done, network connectivity came up and pings were fine.

We are a Cisco only shop and the ESX v3.5 that is in use has the ability to talk via CDP (Cisco Discovery Protocol).  The following command allowed me to view the CDP information and recognize the mis-configured vlan on the external Cisco switch:

esxcfg-info | grep -C 18 ‘\==+CDP Summary’

\==+Physical Nic :
|—-Name………………………………………..vmnic4
|—-PCI Bus……………………………………..26
|—-PCI Slot…………………………………….0
|—-PCI function…………………………………1
|—-MAC Address………………………………….00:15:17:xx:xx:xx
|—-Virtual MAC Address…………………………..00:50:56:xx:xx:xx
|—-Driver………………………………………e1000
|—-Network Hint…………………………………x
|—-MTU…………………………………………1500
|—-Configured Speed……………………………..0
|—-Actual Speed…………………………………1000
|—-Configured Duplex…………………………….0
|—-Actual Duplex………………………………..1
|—-Link Up……………………………………..true
|—-Wake on LAN supported ………………………..false
|—-Wake on LAN enabled ………………………….false
|—-CDP Network………………………………….true
\==+CDP Summary :
|—-Cdp Version………………………………….0
|—-Timeout……………………………………..0
|—-Time-to-live…………………………………135
|—-Samples……………………………………..211
|—-Device Id……………………………………sw-xxx-dr
|—-Ip Address…………………………………..192.x.x.x
|—-Ip Prefix……………………………………0.0.0.0/0
|—-Port Id……………………………………..GigabitEthernet1/0/9
|—-Capabilities…………………………………41
|—-Version……………………………………..Cisco IOS Software, C3750 Softw
|—-Platform…………………………………….cisco WS-C3750G-48TS
|—-Vlan………………………………………..600
|—-Duplex………………………………………true
|—-MTU…………………………………………0
|—-System Name………………………………….
|—-System OID…………………………………..
|—-Mgmt Ip Address………………………………192.x.x.254
|—-Location…………………………………….

This output shows the VLAN being set to 600 on the external Cisco switch where the physical vmnic4 is connected into. This is what caused the network not to come up.  Once the vlan is changed on the Cisco, vmnic4 can be added back into the virtual switch and resume normal functionality.  To add the network port back into the switch, issue the following:

esxcfg-vswitch -L vmnic4 vSwitch0

Other useful commands as follows:

esxcfg-info |grep -i -B 5 hint                   network information per nic
esxcfg-info |grep -i -E “MAC|vmnic”        MAC address information

Note: Only VMWare ESX 3+ supports Cisco CDP


Posted in Networking, VMWare

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