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11

An unmanaged switch doesn't use/care for/understand IP addresses at all. A managed L2 switch uses IP addresses for management only. Some L2 switches also support limited L3/IP functionality like ACLs. L3 switches use IP addresses for L3 forwarding = routing as well. When computer A on a local network wants to communicate with computer B for example through ...


3

To add to AndreKR's answer. There are actually 4 routes that are implicitly added. 10.0.0.1/32 - to CPU route. (Also called punt route) Packets that are destined to this IP address will travel to the router's CPU. For example ping to 10.0.0.1 will be handled by the ICMP application on the router. 10.0.0.0/24 - This is called glean route. Every packet that ...


9

Why in the first case, There was no need of adding Routing table Because it's not really true that there was no need of adding a routing table. When you configured the IP addresses and subnets of the two interfaces, you implicitly added two entries to the routing table, one for each interface/subnet.


4

In the second setup there are 3 ip-subnets involved: 192.168.0.0/24, 192.168.1.0/24 and 192.168.3.0/24. Router2 knows about 192.168.0.0/24 and 192.168.3.0/24 because it has a interface in each. Router4 knows about 192.168.1.0/24 and 192.168.3.0/24 because it has a interface in each. But there is nothing to tie them together so that Router2 knows were to send ...


2

The point is that each node needs to have a route to all the subnets, either a default route (hosts) or a specific route to each subnet (routers). When a node is directly attached to a subnet, a specific route is set up automatically. Otherwise it needs to be set manually by the admin, or learned via a routing protocol from peer gateways. (Hosts often have a ...


8

You don't have to add anything in the 1st case because it's automatic. As there's only one router, it obviously knows everything directly connected to it. When that becomes more than one router, some process needs to be in place to tell the others what isn't local. (either static routes, or any number of dynamic routing protocols.) Thanks to Comments on this ...


5

In your schema the VLAN on the left, let's call it VLAN 10, is associated with subnet 192.168.10.0/24, while the VLAN on the right, which we will call VLAN 20, is associated with 192.168.20.0/24. So you need a gateway for each VLAN, and the only candidate is the switch. It is layer 3 so there's no issue here. Now, the switch receives a packet from a computer ...


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