Ethernet Switching
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Visitor
spravtek
Posts: 8
Registered: ‎01-10-2012
0
Accepted Solution

MSTP question

Hello, 

 

I was wondering if anyone could help me out with some questions around MSTP best practice.

 

A setup with 2 "core switches" and 2 edge switches, core1 is root for instance 1 (with even vlans) and core2 is root for instance 2 (uneven vlans).

 

In the setup I'm looking for the best way to uplink the switches, attached image is what I have so far (it's just a representation)... I'm just wondering if I could use a trunk between core1 and core2 using copper and uplinks to the edge switches fiber (obviously the blocking would not be like in the picture since the cost would be lower over the fibers, the drawing is all uplinks fiber, but I'm just looking if it would be feasible to use copper for the 2 core switches cost wise)

 

So just looking for some insights/ideas ... 

mstp_design

Contributor
Michael Gonnason
Posts: 42
Registered: ‎11-02-2010

Re: MSTP question

Either media should be fine for the switch interconnect.

 

I have connected EX4200s like that in a distribution layer. used two GE ports in an AE, worked well.

Visitor
spravtek
Posts: 8
Registered: ‎01-10-2012
0

Re: MSTP question

Hello Michael,

 

Thanks for the info ... 

 

I was just wondering if it would have impact if I have devices in either even/uneven vlan on both switches, I'm thinking no?

 

The "copper uplink" would be a last resort backup for when all fibers would break/fail, but was unsure if this uplink will be blocked when fibers are still active (since 2times fiber is 4000 against 20.000 for 2times copper it should be, but maybe I'm forgetting something)

 

Thanks again!

 

 

Contributor
Michael Gonnason
Posts: 42
Registered: ‎11-02-2010
0

Re: MSTP question

It should be fine to have the switches alternate root for even/uneven.

 

I did something like this:

 

show configuration protocols mstp
configuration-name datacenter-mst;
revision-level 2;
bridge-priority 24k;
msti 1 {
    bridge-priority 28k;
    vlan 1-125;
}
msti 2 {
    bridge-priority 24k;
    vlan 126-250;
}
msti 3 {
    bridge-priority 28k;
    vlan 251-375;
}
msti 4 {
    bridge-priority 24k;
    vlan 376-500;
}
msti 5 {
    bridge-priority 28k;
    vlan 501-625;
}
msti 6 {
    bridge-priority 24k;
    vlan 626-750;
}
msti 7 {
    bridge-priority 28k;
    vlan 751-875;
}
msti 8 {
    bridge-priority 24k;
    vlan 876-1000;
}
msti 9 {
    bridge-priority 28k;
    vlan 1001-1500;
}
msti 10 {
    bridge-priority 24k;
    vlan 1501-2000;
}
msti 11 {
    bridge-priority 28k;
    vlan 2001-2500;
}
msti 12 {
    bridge-priority 24k;
    vlan 2501-3000;
}
msti 13 {
    bridge-priority 28k;
    vlan 3001-3500;
}
msti 14 {
    bridge-priority 24k;
    vlan 3501-4000;
}
msti 15 {
    bridge-priority 28k;
    vlan 4001-4093;

 

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