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RobstarUSA
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Joined: Sun Apr 15, 2018 5:42 am

SwitchOS not treating lag like single link for spanning tree?

Thu May 28, 2020 12:54 am

Hi all.

I've got a Cisco 3750e with lag to CRS317. Lag looks ok:
Switch#show etherchannel 10 sum    
Flags:  D - down        P - bundled in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
        R - Layer3      S - Layer2
        U - in use      f - failed to allocate aggregator

        M - not in use, minimum links not met
        u - unsuitable for bundling
        w - waiting to be aggregated
        d - default port


Number of channel-groups in use: 1
Number of aggregators:           1

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
10     Po10(SU)        LACP      Te1/0/1(P)  Te2/0/1(P)  
SwitchOS 2.11 LAG looks ok too. If both links are up, I get this in my cisco logs:

May 27 2020 16:45:24.647 CDT: %SW_MATM-4-MACFLAP_NOTIF: Host 3a17.e1de.dda4 in vlan 10 is flapping between port Po10 and port Gi2/0/26

Po10 is the lag. Gi2/0/26 is where the device with the mac is actually at.

I think CRS317 is receiving frames with that mac and flooding it along the other link and not treating the Po as a single logical link.
if I shut one link of the PO the issue goes away.

Anyone seen this before?
 
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Cha0s
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Joined: Tue Oct 11, 2005 4:53 pm

Re: SwitchOS not treating lag like single link for spanning tree?

Fri May 29, 2020 3:14 pm

I've got a CRS317 with LACP bonding.
On the other end I've got two Cisco Nexus 7706 (portchannel with VPC).

I don't have the issue you describe.
But I use RouterOS instead of SwOS.
 
RobstarUSA
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Re: SwitchOS not treating lag like single link for spanning tree?

Thu Jun 04, 2020 6:41 pm

I can't easily go back to RouterOS at this point without taking down my network. So I kinda need a fix. I wonder if it's even a known issue?

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