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ik3umt
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Posts: 255
Joined: Tue Jul 08, 2014 3:58 pm

Broadcast and multicast from different networks

Wed Nov 04, 2015 4:57 pm

Scenario : Few pc on a LAN subnet and few others on a different LAN subnet
All are tepmorarily connected to a single ethernet switch (no VLAN capable) waiting for a second dedicated switch to arrive.
Two ports of this single switch are connected to eth1 and eth2 of a routerboard, these ports have different ip class and are configured as default gateway for each of two lan subnet,

Running torch on each RB ports I see all broadcast and multicast packet coming from both the subnets (also the unwanted one)
Could this bring to particular problems (traffic issue, etc.)??
Can I avoid unwanted subnet packets to be processed by each of RB ethernet ?

Thanks
 
ik3umt
Member Candidate
Member Candidate
Topic Author
Posts: 255
Joined: Tue Jul 08, 2014 3:58 pm

Re: Broadcast and multicast from different networks

Wed Nov 04, 2015 5:07 pm

I.e. I've inserted these two rules :

chain=input action=drop src-address=!10.0.1.0/0 in-interface=ether1
chain=input action=drop src-address=!10.0.2.0/0 in-interface=ether2

(where eth has 10.0.1.1 and eth2 has 10.0.2.1 )

I noted a lot of packet rejected on firewall rules winbox window (Bytes-Packets columns)

Does it have any sense in doing this , or broadcasts/multicasts are rejected anyway from interfaces as they don't belong to their respective subnets ??

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