Uplink from Meraki to Catalyst

[khairul]

Hi Guys,

Currently i am extend existing network. sometimes, the uplink is down from access switch (meraki MS250-48FP) to core switch (catalyst 4503-E). the core switch is running HSRP and access switch is stacking. 

When the uplink down, i can see on the physical port at core switch is up and can see it peer using "sh cdp neig g2/15 details". On meraki physical switch i can see the uplink port got light  but on meraki dashboard it shows down. 

Temporary solution is i down one uplink at core switch and the meraki switch up and working fine. Is there any idea how can it be happen or is it cause by spanning tree?  

[PhilipDAth · Accepted solution]

Spanning tree could cause it - but there is insufficient evidence to say if this is the case.  On your 4503 you should run msp for maximum compatibility with Meraki switches.

spanning-tree mode mst

Also 10.x Meraki MS firmware tends to work much better with Cisco enterprise switches like the 4503.

What type of link is it between these two devices? Gigabit fibre? Gigabit copper?

What appears in the 4503 log when this happens?

When appears in the Meraki switch log when this happens?

[khairul]

Hi Philip,

Thanks. Is there any workaround without reconfigure my 4503 from pvst to mst?

The link between this device is Gigabit Fiber.

on the 4503 is one ip address is looping and hsrp keep changing from active to standby. until i shutdown one of the uplink. even we trace back, cannot find the ip address that show in the log.

on the meraki switch nothing error appear.

[PhilipDAth]

If you don't want to use mst then consider running 10.x firmware on the Meraki MX switches.  mst does produce the most stable configuration though ...

Is there just a single Gigabit fibre between the Meraki MS and the 4503?  If there are no other links then it shouldn't be a spanning tree issue.  Spanning tree doesn't do anything unless there is a loop.

If the 4503 is your core switch - have you made it the root of your spanning tree?

You are running hsrp between the 4503 and what? And what does that other device plug into?

[khairul]

Hi Philip,

Thanks, i will check on the release noted before upgrade to 10.x firmware.

The Uplink have 2 cable between Meraki MS and 4503. In the 4503, did not configure root for the spanning tree.

HSRP is between 2unit of 4503. Other device that plug to the 4503 are the access switch. On meraki switch the device that connected to it are access point (MR74).

[PhilipDAth]

Any reason you are not using LACP between the MS250 and the 4503?  Then it would become loop free again.

[khairul]

Sorry, just now just realize the command " channel-protocol lacp" in catalyst can be issue without command "channel-group X mode on/active" to the interface.

Previously i cannot use LACP because 4503 is just running HSRP without VSS.

Will configure LACP between MS250 and 4503 and monitor.

[PhilipDAth]

Are you saying you have a pair of 4503s (not running VSS) - with a layer 2 link between them.  And you have a Meraki MS250 - and a single layer 2 uplink to each 4503?

If so, you won't be able to use LACP to the 4503s.

I'll say it again, I strongly advise you to:

• Configure your 4503's to be the primary and secondary roots for spanning tree
• Convert to using mst spanning tree on your 4503s
• Run the 10.x code train on the MS250s.

[khairul]

Noted. But if i configure 4503 to be the primary and secondary roots for spanning tree without convert existing spanning-tree from pvst to mst should be no issue right?

[PhilipDAth]

I can't make that guarantee.  I don't know your VLAN structure and what is the root of each VLAN.

A Cisco 4503 can use PVST and RSTP, which maintain per-vlan spanning tree instances.  The rest of the industry, including Cisco Meraki, don't do this.  They use single instance.

So yes - it absolutely can cause issues.

mst on the other hand uses defined instances - and by default that is a single instance.  mst is also compatible with PVST and RSTP as well.

mst is the safest choice.

[khairul]

Noted. right now, configuration is using stp root and secondary

[PhilipDAth]

>On meraki physical switch i can see the uplink port got light  but on meraki dashboard it shows down

This is suspicious.  Are you using a genuine Meraki SFP in the MS250 and a genuine Cisco SFP in your 4503?

Is this single or multi-mode, how long is the fibre, and what grade of fibre are you using?