STP and Portfast trunk

[meistermn]

Our network guys don't like to disable STP or enable portfast trunk.

They fear loops.

How did you convince them?

Physical Switch Optimization

• For Cisco:

Enable port fast / port fast trunk mode on ESX

facing ports not channeling

Removes spanning tree etc.

• Other vendor considerations

Recommendation:

Disable unused switch features that slow link up

[bggb29]

A virtual switch cannot introduce loops.

All portfast does is allow the prot to start passing packets

without going through the bridging learning steps of spanning tree protocol and brings the port

up much faster.

I will look for a something to back this up.

[bertdb]

STP is not needed, because unlike a physical switch, a virtual switch knows immediately which ports are uplinks and which are "endpoint" ports. Therefore, the virtual switch will never send a frame, received from an uplink (=NIC), to another NIC. Hence, no loops can be caused by a virtual switch: the network team's physical switches will never receive a frame from a vSwitch that they sent to the vSwitch themselves.

[bertdb]

Give your network guys this document (official VMware doc) http://www.vmware.com/pdf/esx3_vlan_wp.pdf

and direct them to the questions on page 10:

"

Q: Do any ESX Server virtual switches support per-VLAN Spanning Tree Protocol (STP)?

A: No, ESX Server virtual switches do not support Spanning Tree Protocol. Multiple virtual switches on a single ESX Server system do not create any loops when they connect to the external VLAN or to non-VLAN networks.

"

Sonot only can vSwitches not create loops, they don't support STP. So enabling STP has no benefit whatsoever.

[xooops]

Hi

Our switches running on CatOs. Our Network Engineer told me he can't disable STP on the trunk ports.

cu, sven

[happyhammer]

attached is a Cisco document pages 52 and 53 confirm this to be a best practice, maybe they will accept this as its from CISCO