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What is loop avoidance in switch?
Loop Avoidance – If multiple connections between switches exist for redundancy, network loops can occur. Spanning Tree Protocol is used to stop loops while still allowing redundancy.
How does a switch respond when the frame is received?
When a frame arrives at a switch interface, the switch looks for the destination hardware (MAC) address in its MAC table. If the destination MAC address is found in the table, the frame is only sent out of the appropriate interface. The frame won’t be transmitted out any interface.
How does loop avoidance work?
In BGP there are two loop prevention mechanism:
- for EBGP there is AS-Path attribute which states that router will drop BGP advertisement when it sees it own AS number in AS path attribute.
- for IBGP there is split horizon rule which states that update sent by one IBGP neighbor should be not send to another IBGP neighbor.
What does a switch do with an unknown unicast frame?
Unknown-unicast traffic happens when a switch receives unicast traffic intended to be delivered to a destination that is not in its forwarding information base. In this case the switch marks the frame for flooding and sends it to all forwarding ports within the respective VLAN.
When does a host send a frame through a switch?
Most commonly, this happens when a Switch needs to flood a frame — the frame will get duplicated and sent out every switchport except the switchport which received the frame. Rarely, a host will send a frame with a destination MAC address of itself.
How does host to host through a switch work?
Moreover, when the intended device receives the frame, a response will be generated, which when sent to the Switch will allow the switch to learn and create a MAC Address Table mapping that unknown device to its switchport. Ideally, of course, the Switch will have an entry in its MAC Address Table for every Destination MAC it comes across.
What happens if the source MAC address of a frame change?
If the switch were to change the source MAC address, the destination host would use this MAC address for any responses (including updating any ARP entries with bad data).
What happens when a switch receives an unicast frame?
When a switch receives a frame from a destination it does not know, it inserts the source mac address into its CAM table (a table which maps mac addresses to ports) and forwards the frame to all ports. The process of broadcasting a unicast frame is called unknown unicast.