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New Member

SPT set up for Dual 6500 connection

I have two Cat6509 to interconnect. One in production, using SPT priority 8192 for all VLAN (so it is the root). I need to interconenct a second 6509 in parallel for reduncancy (load balacing and alternative path). I will not be able to use layer 3 immediatelly, but later one when I free up the SUP gig interfaces.

How do I have to configure the SPT for the second SW6509? Should I keep the same priority or increase the priority to keep only one as a root?

  • Other Network Infrastructure Subjects
VIP Purple

Re: SPT set up for Dual 6500 connection


it depends. Are you running ISL trunks between the switches ? If so, you could use PVST (Per-VLAN-Spanning Tree) to load balance traffic (at layer-2) by forwarding some VLANs on one trunk and other Vlans on another trunk without causing a Spanning Tree loop. That would be better than just increasing the STP priority for the second switch and leaving the first switch as the root.



New Member

Re: SPT set up for Dual 6500 connection

Hi Georg,

Thanks, but I will use DOT1Q for the trunks between the switches. I am also planning to have the MSFC2 connected. In fact I intend to have both swithces interconnected in reduncancy. So if one Switch goes down I will have the other handle the core network for that site. Have you done a 6509 interconnection?

Is there any rule of thumb to follow?