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[Possible bug] 6.42.1 - FastPath issue

Thu May 03, 2018 7:57 pm

HW: CRS125-24G-1S
SW: 6.42.1 (current)
Experiencing FastPath issue in the configuration that worked correctly with 6.41.*
The issue is very strange and little bit difficult to exactly pinpoint.
We have multi VLAN environment connected using CRS as central VLAN switch. The switch is used only as L3 switch for inter-vlan routing between vlans and trunks. No other IP feature is used.
Due to this configuration (and high packet rates) we are using FastPath to optimize its performance. I can confirm that fast-path is running form IP settings and CPU load is low.

At the current version, there is an issue with one (only one) port (let's call it P11) that is directly connected to the switch.
This port is used for non-tagged traffic in VLAN1. The issue is that only one VLAN (VLAN 10) cannot communicate with only that one device (P11).
VLAN 10 can communicate with all other VLANs (over 50 VLANs) and with all other devices on VLAN1 (but this one problematic).
The stranges thing is that all other devices on VLAN1 can communicate with the device on P11, so as any other tested VLAN.

If I disable FastPath, everything works fine and VLAN10 can communicate with P1.

I am looking for solution that will allow me to keep using FastPath (I know that FastTrack is alternative, but I need the most optimized solution).
Last edited by Paxy on Thu May 03, 2018 8:15 pm, edited 2 times in total.
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Re: [Possible bug] 6.41.1 - FastPath issue

Thu May 03, 2018 8:02 pm

At the switch, ports are interconnected using the common bridge (bridge-trunk).
All ports are hw-offloaded to this bridge.
Switch->VLANs option in hardware chip is used to filter VLANs on links (I know, it is one old approach, haven't migrated it to the new one yet).

With FastPath:
VLAN10-P11 - not working
VLAN1-P11 - OK
VLAN*-P11 - OK
Without FastPath: All OK
Switching to FastTrack: All OK

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