Hello,
@JAEHOON wrote:
When a wireless client connected to AP # 1 roams to AP # 2, the wireless client's ARP information is loaded simultaneously on eth0 and eth1
This is not possible in JUNOS. JUNOS ARP table always has exactly 1 L2-egress-interface associated with ARP entry.
If You actually mean that ARP update from the client-A who roamed from AP-1 to AP-2 does not rewrite ARP entry in L3 switch, then I'd have to ask - did You actually observe client-A sending ARP req/reply ? Note that non-ARP Ethernet frame with src.MAC of client-A does not rewrite ARP entry, it HAS to be ARP from the client-A.
@JAEHOON wrote:
Clearing the ARP cache manually can solve the problem by correctly learning ARP information, but I do not understand that ARP information is not updated automatically.
It should update automatically as soon as ARP from client-A is received by L3 switch. Please do "monitor traffic interface blah-blah" on L3 switch to confirm client-A sends ARP when it roams behind AP-2.
@JAEHOON wrote:
I am wondering if there is anything to check on my Juniper switch.
You can try "arp-l2-validate" knob on L3 switch' IRB interface if You don't have it already
https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/arp-l2-validate-edit-interfaces.html
Release Information
Statement introduced in Junos OS Release 13.2R4 for EX9200 switches.
Statement introduced in Junos OS Release 15.1R4 for QFX Series switches and EX4300 switches.
The "flooding" as suggested by other poster, would actually help You so it is highly unlikely flooding is responsible for the root cause.
HTH
Thx
Alex