What's the best way to connect two ActivChassis stacks together?

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We have nine switches and it’s becoming very cumbersome to manage them all separately, so I am converting to stacking with ActivChassis. Problem is that ActivChassis only supports eight switches, so I am creating two stacks of two (core) and seven (edge).

The problem is that this approach effectively creates two separate switches and two separate spanning-tree rings.  I THINK I need to create yet another spanning-tree ring tying the two stacks together.  I would create this ring by adding a Dual Stacking XIM module to the Master and Backup on each stack and configuring them as trunk interfaces. This all seems logical to me, but is there someone who can give me a reality check?

Bottom line, I have (or will have) two ActivChassis stacks. What are my options for tying them together?

Thanks in advance.

Keith

[Anonymous · Accepted solution]

Hi Keith,

With respect to spanning-tree, there is actually only one root in both configurations with an 8 switch AC or 2 ( 4 switch AC stacks ).  Also ADTRAN only supports the native ( or untagged ) spanning-tree bpdu's.

In other words ( No PVST or VSTP as some other vendors support. ) on our current Switches ( latest R11.13.0 or older. )  May change in future.

So for optimal spanning-tree convergence time;

1. Choice a root spanning device with the most CPU availability
   with the "#spanning-tree priority 10 "
2. Set all ports that are not connected to other switches to spanning-tree edgeport , to reduce the time needed to wait for a timeout response.  Example -
   

!

interface gigabit-switchport 0/20

  spanning-tree edgeport

  no shutdown

  switchport access vlan 10

!

___________________________________________________________________________________________________________________________________________________________

There are many things to consider when designing an optimal design.

1.  Even though this document does not address the 1638 directly, all the same recommendations are the same for the AC switch stack as any of the other switches.

Switch Provisioning Best Practices

2.  As far as ActivChassis configurations of each of these two new stacks - see

ActivChassis Setup/Design/Maintenance Tips and Best Practices

• Also see the  ActivChassis Limitations in this document.  You can actually increase performance by Reducing the number of AC configured switches.

Each ActivChassis Switch ( numbers updated in AOS Feature Matrix with release numbers);

• Supports 10 port-channels
• Supports 24 ADTRAN Wireless APs
• Supports 256 layer 3 Interfaces
• Supports 2000 Routes
• Supports 32,000 MAC entries
• Supports 4100 ARP entries

The Xim used to cross connect the two AC stacks makes perfect sense.  The Xim ports can be configured like other interfaces as a Trunk, as you said.

Hope this provides a good start to the redesign you are asking about.

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Thanks jroad, great information!