I noticed (based on activity lights) that VLAN traffic between two switch ports are being sent to many switch ports. Here's my scenario:
Port 1 is a "mode access" switchport for VLAN 100 (untagged 100).
Port 2 is a "mode access" switchport for VLAN 101 (untagged 101).
Port 5 is a trunk for VLAN 100 and VLAN 101 (tagged 100, tagged 101).
I have the host on Port 1 talking to the host on Port 2. When they are talking to each other (Unicast), I see port 1, 2, and 5 light up, indicating that its also sending the unicast traffic to port 5. I also confirmed this with Wireshark by seeing the unicast traffic between port 1 and 2 while sniffing packets on port 5. Why is it sending traffic to port 5 when the switch is fully capable of figuring out that the hosts are on Port 1 and Port 2?
My understanding in the past with switches is that it builds a CAM table of mac addresses it sees on ports. It's CAM table should tell the switch that the source and destination hosts are on Ports 1 and 2. There's no reason it should also go to 5 since there is no host there.
This isnt a production switch (yet). So I only have three hosts on my network. Here is my config:
interface vlan 100 ip address dhcp ! interface vlan 101 ! interface ge1 switchport mode access switchport access vlan 100 ! interface ge2 switchport mode access switchport access vlan 101 ! interface ge5 switchport trunk allowed vlan add 100,101 !