topic Spanning-tree Best practices with vPC in Switching

Spanning-tree Best practices with vPC

j.eduardog — Thu, 07 Mar 2019 20:24:39 GMT

Hello,

I am looking for best practices for spanning-tree features in an entire vPC network, read a cisco doc where it says to do not use bridge assurance in a vPC environment. Is there any other spanning-tree feature that we need to look further before applying with vPC, like loopguard or root-guard. Should I take care before applying those features with or without peer-switch vPC feature

Thanks in advance

Re: Spanning-tree Best practices with vPC

Reza Sharifi — Thu, 21 Mar 2013 21:18:41 GMT

Hi,

Yes, there specific recommendation when using spanning-tree with VPC.

Have a look at this link under:

Special Considerations for Spanning Tree with vPCs

http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9670/C07-572834-00_STDG_NX-OS_vPC_DG.pdf

HTH

Re: Spanning-tree Best practices with vPC

sajid_m123 — Thu, 21 Mar 2013 21:21:31 GMT

Reza,

Is there any impact on hardware resources on switches if I enable RSTP in an environment?

Spanning-tree Best practices with vPC

Reza Sharifi — Thu, 21 Mar 2013 21:35:08 GMT

For the Nexus Series, the default is Rapid PVST+. If you don't have a whole a lot of vlans, I would stay with RSTP. If you have a lots of vlans, then MST probably scales better.

MST Compared to Rapid PVST+

MST allows you to assign two or more VLANs to a spanning

tree instance. MST is not the default spanning

tree

mode; Rapid PVST+ is the default mode on Cisco

switches.

MST instances with the same

name, revision number, and VLAN

instance mapping combine to form an MST

region. The MST region appears as a single bridge to spanning

tree configurations outside the region.

The advantages of MST over Rapid PVST+ are as follows:

●

MST is an IEE

E standard.

●

MST is more resource efficient. In particular, the number of BPDUs transmitted by MST does not depend on

the number of VLANs, as Rapid PVST+ does.

●

MST decouples the creation of VLANs from the definition for forwarding the topology.

●

MST simplifies the depl

oyment of stretched Layer 2 networks, because of its ability to define regions.

For all these reasons, it is advisable for many deployments to migrate to an MST

based topology.

http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9670/C07-572834-00_STDG_NX-OS_vPC_DG.pdf

HTH

Re: Spanning-tree Best practices with vPC

sajid_m123 — Thu, 21 Mar 2013 21:39:12 GMT

Reza,

Thanks for the good info. My question is that is there any impact on network performance due resource consumption if I enable RSTP on all the switches in a network?

Spanning-tree Best practices with vPC

Reza Sharifi — Thu, 21 Mar 2013 21:44:06 GMT

Usually, there is not, but how large is the network? What type of devices are you using and how many vlans?

Re: Spanning-tree Best practices with vPC

sajid_m123 — Thu, 21 Mar 2013 21:49:58 GMT

Around 50 Vlans with overall 60 switches. Switches range from 3550, 3560, 3750, 3760, 4500, 6500

Re: Spanning-tree Best practices with vPC

j.eduardog — Thu, 21 Mar 2013 21:58:07 GMT

Better open another topic for you sir, thanks

Spanning-tree Best practices with vPC

j.eduardog — Thu, 21 Mar 2013 21:59:26 GMT

Thanks for the link you provided, but what about using or not using loopguard in the access switches, is that a best practice using it even with vPC or no need to use it?

Thanks

Spanning-tree Best practices with vPC

Reza Sharifi — Thu, 21 Mar 2013 22:16:54 GMT

It is usually a good practice to enable loop guard on both sides of your link:

Loop Guard

Loop Guard provides additional protection against Layer 2 forwarding loops. Loop Guard should be enabled on root and alternate ports in the spanning tree topology. When Loop Guard detects that BPDUs are no longer being received on a non-designated port, the port is moved into a loop-inconsistent state instead of transitioning to the listening/learning/forwarding state. This prevents a Layer 2 loop from occurring in the event that a link becomes unidirectional or a node stops transmitting BPDUs for some reason. Loop Guard may also be configured globally, but port-specific configuration is preferred to ensure that it is only enabled where specifically necessary. An illustration of where to enable Loop Guard, Root Guard, and BPDU Guard spanning tree enhancements is shown in Figure 6.

more info here:

http://www.cisco.com/en/US/docs/solutions/Enterprise/Data_Center/nx_7000_dc.html

HTH

Spanning-tree Best practices with vPC

j.eduardog — Fri, 22 Mar 2013 01:07:04 GMT

There is no specific recommendation about STP features with a full vPC environment in those links

Thanks anyway