Does Router Broadcast or not ?
Friends,
I am having a doubt regarding broadcasting done by router or not ?
Suppose we are having this scenario.
LAN1 { 172.19.1.1 ,172.19.1.2 ,172.19.1.4,172.19.1.8 } connected via S1
LAN2 { 172.17.12.1 , 172.17.12.5 , 172.17.12.7 , 172.17.12.9 } connected via S2
Now Consider Switch S1 and S2 and a router R.
See this :-
LAN1 <----S1----> R <-------S2----->LAN2
I Hope the scenario is clear.
Now if computer on LAN1 broadcasts a packet.
It will also reach the Router.
Packet is having IP address as broadcast address.
The Question is Will the Router check the address in the routing table ?
or simply drop the packet due to broadcast address.
Please reply...😛
Answer:
TLDR; the routers do not broadcast packets on to other networks. Let me explain.
Your question revolves around how routers handle broadcast packets.
Routers are designed to limit the scope of broadcast packets. This means they don't typically forward broadcast packets onto other networks.
This behavior is crucial for limiting broadcast traffic and preserving bandwidth on a network. If routers forward broadcasts without any controls in place, broadcast traffic could flood and slow down the entire network.
Now, to your question. When a computer on LAN1 sends a broadcast packet, it will be received by all devices on LAN1, including the switch S1 and router R.
The router, upon receiving the broadcast packet, would not check its routing table for where to send it next.
This is because broadcast packets are meant to be delivered to all devices on the same local network (LAN1 in this case), not to devices on a different network (like LAN2).
Therefore, the router R would not forward the broadcast packet onto LAN2. It simply drops the broadcast packet, stopping it from propagating beyond its original network (LAN1).
So, the router does not typically "broadcast" in the sense of forwarding broadcast packets onto other networks.
The router can, however, broadcast within its own local network, if for example, it needs to distribute information to all devices on its network. This type of broadcast is still confined to the local network.
This behavior is described by default in IPv4 networks. In special cases or with different protocols, this might be different. For instance, certain configurations or technologies (like VPNs, or in case of IPv6, the multicast traffic) might allow a form of "broadcast" or "multicast" to pass between networks under controlled circumstances.