When does we call something a layer 3 or layer 2 device ?
A router is a layer 3 device because it takes forwarding and routing decisions depending on the Layer 3 header. Also Layer 2 header addresses gets changed when it passes through a router.
So whether we can call a Switch - who can create VLANs based on IP addresses a Layer 3 device ? May be or may not. Although it looks into the IP headers, the Layer 2 addresses remain unchanged even after it goes through a VLAN switch. So its still a Layer 2 device.
Disclaimer: I am just understanding networking and discussing myself. My interpretations may be wrong.
Feedbacks I received on this from a networking expert:
A device is in l2, if it does l2 fn, i.e., bridging
device is l3, if it routes
if a switch routes packets, it is a router
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- Anoop G
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1 comment:
If the MAC address received on the ingress packet is the VLAN Mac address it has to be routed :-) L2 gives responsibility to L3 -> Switch switches to router :-)
IP Vlan(rather protocol vlan) is still an L2 stuff... since the treatment is same as port Vlan.
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