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PVSTP is backwork compatibile with RSTP

gianluca811
Level 1
Level 1

Hi,

I need to attach a Nexus 3500 to a switch of another vendor.

Nexus run pvstp, the other vendor run RSTP and is the root bridge.

Do you think I will have problem with STP ? The PVSTP is backword compatible with RSTP ?

Thanks

7 Replies 7

Mark Malone
VIP Alumni
VIP Alumni

Yes it will work but your limited to 128 vlan instances from what I remember , as well some 3rd party switches requires that vlan 1 be set untagged on Cisco ports connected to there switches , you might not want the other switch as the root though I would have the pvst as the root and check there requirement for interoperability first with pvst

Im not going to say you wont have some problem getting this going as nearly always from what I have seen mixing vendors and different types of stp interoperability things never go that smooth in setup but it is doable

ok thanks. the other vendor is BNT and must be root  bridge.

I think the mstp can be also a better solution. anyway I will try both.

If you have any other comment please let me know, will be very worth for me.

Is there a reason it has to be the root bridge , you would want your most powerful and centralized switches to be the root bridge

I know some BNP switches you can manually set the bridge priorities etc to aloow Cisco to be the root

the bnt is the core switch, the nexus is an access.

There are other access switch all bnt.

So for this reason the core bnt is the root bridge and the access nexus is not root.

ah ok that will be smoother then that Nexus is access , it should integrate ok.

If the Nexus was the core and your introducing a new switch and setting it as root is where you might see some problems as there would be large calculation and that's where the interoperability can go wrong

I thought 3500 would support rstp anyway why set it as pvst

Table 2.       Software Licensing for Cisco Nexus 3500

Software Package

Features Supported

System default (no license required)

  Comprehensive Layer 2 feature set: VLAN, IEEE 802.1Q trunking, Link Aggregation Control Protocol (LACP), Unidirectional Link Detection (UDLD; Standard and Aggressive), Multiple Spanning Tree Protocol (MSTP), Rapid Spanning Tree Protocol (RSTP), and Spanning Tree Protocol guard
  Security: Authentication, authorization, and accounting (AAA), access control lists (ACLs), storm control, and configurable Control-Plane Policing (CoPP)
  Management features: Cisco Data Center Network Manager (DCNM) support, Secure Shell Version 2 (SSHv2) access, Cisco Discovery Protocol, SNMP, syslog, and IEEE 1588 PTP
  Monitoring features: Advanced buffer monitoring, SPAN, and ERSPAN

thanks a lot for your support.

From further google surfing, I think a better option is enable Multiple spanning tree instead of pvstp.

What do you think about ?

The only thing id be concerned of with MST is they say its always supposed to be the root when it set with other types of STP , so if its pvst and mst all cisco the mst should be root

Not sure if the same is applied when its different vendors but it may be as I think its something to do with the way mst is designed the cst needs to be the root so this may not work if you want the BNP to be root , I have seen cases with pvst and mst together , pvst was set as root but on the mst switches there were constant errors coming in from pvst switches due to it being set like this

when the mst was made the root the errors in logs went away