Hi
First let's have a look at the EVPN RFC 7432:
"If a bridged network is multihomed to more than one PE in an EVPN network via switches, then the support of All-Active redundancy mode
requires the bridged network to be connected to two or more PEs using a LAG.
If a bridged network does not connect to the PEs using a LAG, then only one of the links between the bridged network and the PEs must be
the active link for a given <ES, VLAN> or <ES, VLAN bundle>."
Basically if it's multihomed it must be a LAG, if it's multihomed without a LAG it must be Active/Standby.
In your topology the switch on the left should be connected using ESI-LAG to avoid any loops.
The switches on the right should be stacked so they act as one logical device then multihomed using ESI-LAG.
If they can't be stacked then the red line describes a common miswiring scenario.
This will trigger a MAC flap between QFX3 and QFX4, EVPN handles this with duplicate-address-detection:
Changing Duplicate MAC Address Detection Settings | EVPN User Guide | Juniper Networks TechLibraryNote that DAD till only solve the control plane, BUM traffic will still loop between QFX3, QFX4 and the switches/red line behind.
What you want to do here is to enable the new EVPN loop-detect feature on the ports facing the switches:
loop-detect (EVPN) | EVPN User Guide | Juniper Networks TechLibraryHope this helps.
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ROGER WIKLUND
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Original Message:
Sent: 04-03-2021 23:53
From: Unknown User
Subject: Anyone can help to take a look at my topology to see any issues with it?
I have the following topology: