Can different vlans communicate without a router. I had searched online, but I got a different answers from different websites. Without these you cannot have inter-vlan routing. But today, I heard sth really interesting from my coworker(I am really new to networking). Nov 20, 2024 · Private VLANs, supported on Cisco platforms, provide isolated VLANs with no communication between VLAN ports except for one designated port for layer-3 functions. However, VLANs are isolated from one another by default, meaning devices in different VLANs cannot communicate unless we enable Inter-VLAN Routing. It would be a feature specific to your router. Jun 7, 2025 · Understanding VLAN tagging is essential for implementing more advanced networking concepts like inter-VLAN routing, which allows devices on different VLANs to communicate with each other through a router or layer 3 switch. You still need a router or something that can route "in between" VLANs. Each vlan is a different ip subnet. Sep 23, 2008 · In other words - you can use this one interface for managing the box (telnet to it for example), but the box will never be able to do inter VLAN routing without help of an external router. You can either have them on a L3 switch or on a routers sub-interface with trunking (router-on-a-stick) 1 Spice up brianwhelton (brianwhelton) September 14, 2015, 6:21am 3 What he said basically. VLANs are layer 2, to provide IP connectivity from one VLAN to another they need to have However, if there's nothing separating the two hosts at Layer 2 (such as a VLAN), and the sender knew the recipients MAC address, they could manually put a packet on the wire with the correct destination IP and MAC addresses to have it picked up off the wire by the recipient, bypassing the router. Dec 15, 2020 · In a properly designed IP network, a VLAN should map to a single broadcast domain, which should map to a unique IP network. VLANs are good but you need to firewall them off if you don’t want them to talk. Dec 15, 2020 · For ease of troubleshooting, traffic from one VLAN should not reach another VLAN without an OSI Layer 3 device, such as a router. But it is possible to provide communication between two different vlans without using any layer 3 device. That is why every VLAN traditionally requires it's own unique IP subnet -- because if any communication is to happen between those VLANs, unique subnets will be required. Otherwise, yes, your router that you build the VLANs in allows them to talk. Routers route packets between different networks. Each vlan can not talk to another vlan without a router with an ip address in the vlan to act as a gateway out of the vlan. limiting the ports on which broadcast traffic is flooded or visible. If you just stuck them on a dumb switch, yes there are ways for them to communicate. Nov 6, 2022 · In my previous understanding, there is no way to communicate between two VLANs using only layer 2. Aug 21, 2019 · So, say you have vlan 10 and 20 on one switch and you configure the same 2 vlans in the second switch and create an svi for each vlan with IP. In this discussion, lets explore the best ways to set up Inter-VLAN Routing on Cisco devices, using simple explanations and clear examples to help configure network efficiently. They claim that 1. Notes: More about the virtual LANs, Physical LANs and briefly reviewed VLAN configuration options you can read the articles shared here: Virtual vs. Jan 12, 2015 · In order to perform communication between two different vlans we require a router or mls. This can be done depending on the equipment you use. Bottom line: Though routers play a critical role, with certain configurations and special cases, two VLANs can technically communicate without using a typical router setup, but never without routing. VLANs partition switches, i. Nov 20, 2015 · In this article we will discuss how to establish communications between VLANs, as well as how to configure the networks. Is this possible? Oct 11, 2013 · A 'Vlan' is a Layer 2 broadcast domain by default meaning if you simply created two Vlan's on a single switch (without a Vlan interface), the hosts would be able to communicate with hosts inside the same Vlan as them but not with hosts on other Vlans. For ease of troubleshooting, traffic from one VLAN should not reach another VLAN without an OSI Layer 3 device, such as a router. Apr 11, 2019 · If you want to communicate between VLANs you will have to implement some kind of routing between them, because otherwise they will be completely isolated. Nov 8, 2024 · Therefore, even if devices share the same subnet, they cannot communicate across VLANs without routing, as each VLAN isolates network traffic at the data link layer. May 28, 2025 · Why can’t devices in different VLANs communicate on a Cisco switch? Learn how a Layer 3 device enables inter-VLAN routing and what’s required for cross-VLAN communication—essential for Cisco Certified Field Technician (CCT) exam success. Even if devices in different networks are on the same layer-2 broadcast domain, you need a router to let the devices communicate at layer-3. That is the purpose of a router. *Communication between different VLANs means A PC 1 in VLAN10 communicates with PC 2 in VLAN20 edit: Thank you all ans all 1-3. After all, this is the purpose of having VLAN. It's possible some "Layer 2 router" devices may have this feature. When they say they cannot communicate with each other, they are presuming the machines are on different switches or different vlans. Mar 6, 2016 · It is clear that hosts on two different VLANs can't directly communicate on a single switch, but how do they communicate to each other at all? Do they use a router? How does it work? May 8, 2017 · 19 Devices in different subnets can communicate. Jul 18, 2018 · Devices in the VLAN would have access to the router via that gateway address, the device that does the inter-vlan-routing can have policies permitting or rejecting traffic between VLANs. Jul 19, 2006 · It's weired, I can ping the 2 diffrent IP of the switch on the two different VLAN from the host on the new VLAN, but I can't ping the new VLAN ip from an host on the old VLAN. Mar 12, 2018 · Hi, I was asked in an interview that two hosts connected through 2 cisco 2950 switches in different vlans should communicate each other without using layer 3 device and l3 switch. VLANs can communicate with other VLANs when May 10, 2023 · Without inter VLAN routing, devices in different VLANs are isolated and cannot communicate with each other, limiting the flexibility and functionality of the network. Nov 7, 2022 · Another one said that native VLAN can access other VLANs under the same layer 2 switch. Now, if you have a host in one of the vlans connected to the first switch and need to communicate with a different host in a different vlan on the second switch you would need a trunk between the 2 switches. Layer-3 switches are just switches with a router built into them so they can perform intervlan routing. Allow me to also ask one last question. Aug 29, 2017 · Intervlan routing is usually applied on a L3 capable switch to allow communication between different vlans on your network - (inter-vlan routing) meaning the switch is able of perform routing functions just like a physical router can do. . Learn what a Router Sub-interface and a L3 Switch is, as well as how to configure both of them on Cisco devices to enable Routing between VLANs. Physical LANs: Device Functionalities and VLAN Configuration Fundamentals and Commands First of Apr 11, 2019 · And due to how Router's work, each router interface must have it's own, unique IP Subnet. Apr 14, 2019 · Why do devices on two separate VLANs (Virtual LANs) implemented on the same switch require a router to communicate? VLANs: How can I get 2 devices on different VLANs to communicate with each other w/o compromising overall network security? Background is that I have a dedicated subnet (VLAN1) for all my IoT devices, while all my other devices reside on another one (VLAN2). Feb 13, 2020 · All the three switches have an active VLAN interface on a different network than the other two They are able to ping each other without a router Cisco switches do ping each other even if their IP address are in different networks And we know that different networks do not ping each other without a Layer 3 device, even if they are on a same VLAN Jun 22, 2025 · Inter-VLAN routing allows devices in different VLANs to communicate with each other using a router or Layer 3 switch. e. A vlan is simply a logical version of one of the switches above. Sep 14, 2015 · To route traffic you need an IP address and a gateway. fnd1 5a6h0 tezps2 ixn4h vr lssy rh fvd5q 9kyfa eatsba