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I have a scenario, (shown in attach diagram)enter image description here where i need to merge traffic from two server 1 , 2 to target server 3. All three are on different vlans/subnets.

With layer 3 switch in between would it be possible to route traffic through acl or routing policy to send traffic to target server 3. Also pls note that this is bi-directional traffic , target server 3 is communicating using rtsp with streams from server 1 and 2. Thanks.

See correction: Its mistake in my diagram server 2 is 10.10.30.x network.

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    If you have a router (a layer-3 switch has a router), you can send traffic from one or more hosts to one or more other hosts. That is what routers do, they route packets between networks. I do not understand the problem. – Ron Maupin Jun 22 at 15:02
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A layer-3 switch can easily be set up as router, so your best choice is to activate routing there and set it as gateway.

If there's a (WAN) router elsewhere you need to be sure that the L3 switches default route points there and that the router has a route for the subnet behind the L3 switch.

ACLs or policies are only required when you need to filter traffic across the L3 switch.

Another option is to bridge the VLANs. Note that without renumbering you still need to route between different subnets even if they live inside the very same L2 segment/VLAN. If you don't want to renumber Server 3's interface you should consider adding a secondary IP address from 10.10.20.0/24 to avoid routing.

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  • +1 thanks Zac67, I have made a correction server 2 is a different network also, from bridging do you mean like route traffic between servers using l3 switch as a gateway, with a target server connecting to uplink switch? And no its not WAN switch its inside LAN and all traffic is local. – asadz Jun 22 at 16:19
  • Bridging means connecting on L2 (across a switch). Across a router is called routing. You can route Server 2's subnet on the L3 switch just as well. – Zac67 Jun 22 at 16:26
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If you don't want to re-address your devices, you will have to keep the networks for Server 1 and Server 2 at layer 2. You will have one VLAN connecting your devices. If they are currently on different VLANs, you can change the VID to be the same on all switches.

Depending on the distances, topology, and number of devices, you may want to consider breaking up the network into multiple subnets (layer 3) and route between them. The disadvantage of this is you will have re-address one of the two existing networks. The network for server 3 does not need to change for that.

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  • +1 thanks @Ron, so if all switches are on same clan, it be single broadcast domain, then I don't want to use layer 3 switch in middle as gateway it be just layer 2 communication? – asadz Jun 22 at 16:20

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