Hiall, I've had stunning good results with MikroTik switches running SwOS, but recently made the mistake of getting a switch (CRS112-8P-4S-IN) without realising it only comes with RouterOS. I'm trying to have a pretty basic setup: * VLAN 1 - untagged, all ports * VLAN 66 and VLAN 68 - tagged, all ports * VLAN 64 - tagged, ether8, sfp9, sfp10, sfp11, sfp12 * Management via /24

Asked 5 years, 9 months ago Viewed 6k times I'm trying to understand the specifics of trunking a VLAN on two switches. Say I have two switches, both hosting half of VLAN 3. Switch 1 Ports 0-5 on VLAN 3, Port 6 is Trunk Switch 2 Ports 0-5 on VLAN 3, Port 6 is Trunk Do the two switches know what the MAC addresses are of the devices connected to the other switch which are in the same VLAN, or do the switches just know that Port 6 is a VLAN 3 trunk and when they receive a broadcast frame, they just flood the frame to the trunk port with the VLAN tag and expect the switch on the other end to deal with it? Ron Maupin♦ gold badges113 silver badges190 bronze badges asked Sep 11, 2017 at 1511 When a frame enters a switch, the switch will take the source MAC address and update its MAC address table with the interface where the frame entered the switch. That interface can be an access or trunk interface. Broadcast or unknown unicast frames will be sent to all interfaces except the one where the frame entered the switch, including access and trunk interfaces. Known unicast frames will be sent to the switch interface indicated in the switch MAC address table, whether an access or trunk interface. answered Sep 11, 2017 at 1516 Ron Maupin♦Ron gold badges113 silver badges190 bronze badges 6 VLAN3 is just a subnet or another network. Say you have vlan 1 and vlan 3 is Each device in vlan 3 will get the IP. That IP is assigned to the MAC address of the end device This is held in the arp table on a layer 3 device. Only the switch, as it is a layer 2 device, only knows the MAC address of the devices directly attached to it. A Trunk port allows for multiple networks or VLANS to communicate over the same port, But without a layer 3 they cannot talk to one another. A broadcast will be sent to any device on that VLAN or network. It doens't care if it's on switch one or two. answered Sep 11, 2017 at 1518 3 There's 2 thing in your question. First if you consider a single vlan, the port 6 being a trunk is not mandatory, setting the port 6 of both switch as VLAN3 will work. A trunk port has interest when you have multiples vlan on a switch, this mean you have made partitions on your switch, port 1 to 5 on VLAN3, port 7 to 12 on VLAN 4 for example, and you configure your port 6 as trunk to transport vlan 3 and 4. You may achieve the same thing without a trunk port if you keep port 6 in vlan 3 and use port 12 in VLAN 4 to link the two switches for example. A switch records incoming mac address on a port, such that when a packet is directed to a mac address it know where to send it, when it don't know or if it's a broadcast it send it on all ports within the same vlan, trunk included and the switch receiving the packet will scan it's own table before forwarding the packet to the correct port if already know or on all port within the vlan if the mac address is unknown or broadcast. Mainly a vlan is a virtual switch within the switch and the trunk is an aggregation of "virtual ports" to transport multiple vlans on a single link trunk on multiple links are trunks made on port aggregation LACP and are another subject. answered Sep 11, 2017 at 1541 "Switch 2 Ports 0-5 on VLAN 3, Port 6 is Trunk" .. Switch 2 knows that Vlan 3 information on sw1 from switch 1 Port6 mac -address . Through this mac-address frame is forwarded to switch2 from switch 1 After frames is in switch 2 . Traffic will further checks for mac -address table in switch 2, with the reference to this mac -address table frame is forwarded on required interfàce where destination host is connected. answered Dec 10, 2020 at 1150 Sagar UragondaSagar Uragonda8371 gold badge15 silver badges73 bronze badges

MultilayerSwitch atau Switch Layer 3 adalah switch yang memiliki kemampuan layaknya router yakni menghubungkan host-host yang berbeda jaringan. Dengan menggunakan Multilayer Switch, konfigurasi pembuatan vlan dan menghubungkan antar vlan dapat dilakukan tanpa perlu menambahkan perangkat router.

We wrote an article which covers Virtual Local Area Networks VLANs as a concept, and another article on configuring VLANs on Cisco switches. The remaining subjects to cover are the different options that exist for routing between VLANs. This will let us illustrate the concepts of inter-vlan routing, Router on a Stick RoaS, and Layer 3 Switches occasionally called MultiLayer Switches. Why do we need Routing Between VLANs? As we learned in a prior article, VLANs create a logical separation between Switch ports. Essentially, each VLAN behaves like a separate physical switch. To illustrate this, below are two topology pictures of the same environment – one Physical and one Logical. The Physical topology depicts a switch and four hosts in two different VLANs – Host A and Host B are in VLAN 20 and Host C and Host D are in VLAN 30. The logical topology reflects how the physical topology operates – the two VLANs essentially create two separate physical switches. Despite all four hosts being connected to the same physical switch, the logical topology makes it clear that the hosts in VLAN 20 are unable to speak with the hosts in VLAN 30. Notice since there is nothing connecting the two “virtual” switches, there is no way for Host A to speak to Host C. Since Host A and Host C are in different VLANs, it is also implied that they are in different Networks. Each VLAN will typically correspond to its own IP Network. In this diagram, VLAN 20 contains the network, and VLAN 30 contains the network. The purpose of a Switch is to facilitate communication within networks. This works great for Host A trying to speak to Host B. However, if Host A is trying to speak to Host C, we will need to use another device – one whose purpose is to facilitate communication between networks. If you’ve read the Packet Traveling series, then you know that the device which facilitates communication between networks is a Router. A router will perform the routing function necessary for two hosts on different networks to speak to one another. In the same way, a Router is what we will need in order for hosts in different VLANs to communicate with one another. There are three options available in order to enable routing between the VLANs Router with a Separate Physical Interface in each VLAN Router with a Sub-Interface in each VLAN Utilizing a Layer 3 Switch The remainder of this article will explore these three options and their configuration. Router with Separate Physical Interfaces The simplest way to enable routing between the two VLANs to simply connect an additional port from each VLAN into a Router. The Router doesn’t know that it has two connections to the same switch — nor does it need to. The Router operates like normal when routing packets between two networks. In fact, the process of a packet moving from Host A to Host D in this topology will work exactly as it does in this video. The only difference is since there is only one physical switch, there will only be one MAC address table – each entry includes the mapping of switchport to MAC address, as well as the VLAN ID number that port belongs to. Each switch port in this diagram is configured as an Access port, we can use the range command to configure multiple ports as once Switchconfig interface range eth2/0 - 2 Switchconfig-if-range switchport mode access Switchconfig-if-range switchport access vlan 20 Switchconfig interface range eth3/0 - 2 Switchconfig-if-range switchport mode access Switchconfig-if-range switchport access vlan 30 Of course, before assigning the switchport to a VLAN, it is a good idea to create the VLAN in the VLAN Database. The Router interfaces also use a standard configuration — configuring an IP address and enabling the interface Routerconfig interface eth0/2 Routerconfig-if ip address Routerconfig-if no shutdown Routerconfig interface eth0/3 Routerconfig-if ip address Routerconfig-if no shutdown Below you will find various show commands for the Router and the Switch, these can be used to understand and validate how the environment is functioning. Router Show Commands show runip int briefip routearpcdp neighbor Router show running-config ... interface Ethernet0/2 ip address ! interface Ethernet0/3 ip address Router show ip interface brief Interface IP-Address OK? Method Status Protocol ... Ethernet0/2 YES manual up up Ethernet0/3 YES manual up up ... Router show ip route Codes L - local, C - connected, ... Gateway of last resort is not set is variably subnetted, 4 subnets, 2 masks C is directly connected, Ethernet0/2 L is directly connected, Ethernet0/2 C is directly connected, Ethernet0/3 L is directly connected, Ethernet0/3 Router show arp Protocol Address Age min Hardware Addr Type Interface Internet - ARPA Ethernet0/2 Internet 2 ARPA Ethernet0/2 Internet 5 ARPA Ethernet0/2 Internet - ARPA Ethernet0/3 Internet 4 ARPA Ethernet0/3 Internet 4 ARPA Ethernet0/3 Router show cdp neighbors Capability Codes R - Router, S - Switch, I - IGMP, B - Source Route Bridge ... Device ID Local Intrfce Holdtme Capability Platform Port ID Switch Eth 0/3 126 R S I Linux Uni Eth 3/0 Switch Eth 0/2 126 R S I Linux Uni Eth 2/0 Switch Show Commands show runmac tablevlan briefcdp neighbor Switch show running-config ... vlan 20 name RED ! vlan 30 name BLUE ... interface Ethernet2/0 switchport access vlan 20 switchport mode access ! interface Ethernet2/1 switchport access vlan 20 switchport mode access ! interface Ethernet2/2 switchport access vlan 20 switchport mode access ! interface Ethernet3/0 switchport access vlan 30 switchport mode access ! interface Ethernet3/1 switchport access vlan 30 switchport mode access ! interface Ethernet3/2 switchport access vlan 30 switchport mode access Switch show mac address-table Mac Address Table - Vlan Mac Address Type Ports - - - - 20 DYNAMIC Et2/1 20 DYNAMIC Et2/2 20 DYNAMIC Et2/0 30 DYNAMIC Et3/1 30 DYNAMIC Et3/2 30 DYNAMIC Et3/0 Total Mac Addresses for this criterion 6 Switch show vlan brief VLAN Name Status Ports - - - - ... 20 RED active Et2/0, Et2/1, Et2/2 30 BLUE active Et3/0, Et3/1, Et3/2 ... Switch show cdp neighbors Capability Codes R - Router, S - Switch, I - IGMP, B - Source Route Bridge ... Device ID Local Intrfce Holdtme Capability Platform Port ID Router Eth 3/0 152 R B Linux Uni Eth 0/3 Router Eth 2/0 166 R B Linux Uni Eth 0/2 Router with Sub-Interfaces The previously described method is functional, but scales poorly. If there were five VLANs on the switch, then we would need five switchports and five router ports to enable routing between all five VLANs Instead, there exists a way for multiple VLANs to terminate on a single router interface. That method is to create a Sub-Interface. A Sub-Interface allows a single Physical interface to be split up into multiple virtual sub-interfaces, each of which terminate their own VLAN. Sub-interfaces to a Router are similar to what Trunk ports are to a Switch – one link carrying traffic for multiple VLANs. Hence, each router Sub-interface must also add a VLAN tag to all traffic leaving said interface. The logical operation of the Sub-interface topology works exactly as the separate physical interface topology in the section before it. The only difference is with Sub-interfaces, only one Router interface is required to terminate all VLANs. Keep in mind, however, that the drawback with all VLANs terminating on a single Router interface is an increased risk of congestion on the link. The Sub-interface feature is sometimes referred to as Router on a Stick or One-armed Router. This is in reference to the single router terminating the traffic from each VLAN. The Switch’s port facing the router is configured as a standard Trunk Switchconfig interface eth1/1 Switchconfig-if switchport trunk encapsulation dot1q Switchconfig-if switchport mode trunk The Router’s configuration of Sub-interfaces is fairly straight forward. First, we enable the physical interface Routerconfig interface eth1/1 Routerconfig-if no shutdown Next, we create and configure the first Sub-interface Routerconfig interface eth1/ Routerconfig-subif encapsulation dot1Q 20 Routerconfig-subif ip address Apart from using the Sub-interface distinguisher eth1/ and using the encapsulation dot1q command, the rest of the interface configuration is exactly the same as any other regular physical interface. Similarly, we will also configure the Sub-interface for VLAN 30 Routerconfig interface eth1/ Routerconfig-subif encapsulation dot1Q 30 Routerconfig-subif ip address A point of clarity regarding the Sub-interface syntax. The number after the physical interface fa0/ and fa0/ simply serves the purpose of splitting up the physical interfaces into Sub-interfaces. The number specified in the encapsulation dot1q vlan command is what actually specifies what VLAN ID the traffic belongs to. These two values do not have to match, but often they do for the purpose of technician sanity. Below you will find various show commands for the Router and the Switch. These can be used to understand and validate how the environment is functioning. Router Sub-Interface Show Commands show runip int briefip routearpcdp neighbor Router show running-config ... interface Ethernet1/1 no ip address ! interface Ethernet1/ encapsulation dot1Q 20 ip address ! interface Ethernet1/ encapsulation dot1Q 30 ip address Router show ip interface brief Interface IP-Address OK? Method Status Protocol ... Ethernet1/1 unassigned YES NVRAM up up Ethernet1/ YES manual up up Ethernet1/ YES manual up up ... Router show ip route Codes L - local, C - connected, ... Gateway of last resort is not set is variably subnetted, 4 subnets, 2 masks C is directly connected, Ethernet1/ L is directly connected, Ethernet1/ C is directly connected, Ethernet1/ L is directly connected, Ethernet1/ Router show arp Protocol Address Age min Hardware Addr Type Interface Internet - ARPA Ethernet1/ Internet 0 ARPA Ethernet1/ Internet 0 ARPA Ethernet1/ Internet - ARPA Ethernet1/ Internet 0 ARPA Ethernet1/ Internet 0 ARPA Ethernet1/ Router show cdp neighbors Capability Codes R - Router, S - Switch, I - IGMP, B - Source Route Bridge ... Device ID Local Intrfce Holdtme Capability Platform Port ID Switch Eth 1/1 150 R S I Linux Uni Eth 1/1 Switch Trunk Show Commands show runmac tablevlan briefint trunkcdp Switch show running-config ... vlan 20 name RED ! vlan 30 name BLUE ... interface Ethernet1/1 switchport trunk encapsulation dot1q switchport mode trunk ! interface Ethernet2/1 switchport access vlan 20 switchport mode access ! interface Ethernet2/2 switchport access vlan 20 switchport mode access ! interface Ethernet3/1 switchport access vlan 30 switchport mode access ! interface Ethernet3/2 switchport access vlan 30 switchport mode access Switch show mac address-table Mac Address Table - Vlan Mac Address Type Ports - - - - 1 DYNAMIC Et1/1 20 DYNAMIC Et1/1 30 DYNAMIC Et1/1 20 DYNAMIC Et2/1 20 DYNAMIC Et2/2 30 DYNAMIC Et3/1 30 DYNAMIC Et3/2 Total Mac Addresses for this criterion 7 Switch show vlan brief VLAN Name Status Ports - - - - ... 20 RED active Et2/1, Et2/2 30 BLUE active Et3/1, Et3/2 ... Switch show interfaces trunk Port Mode Encapsulation Status Native vlan Et1/1 on trunking 1 Port Vlans allowed on trunk Et1/1 1-4094 Port Vlans allowed and active in management domain Et1/1 1,20,30 Port Vlans in spanning tree forwarding state and not pruned Et1/1 1,20,30 Switch show cdp neighbors Capability Codes R - Router, S - Switch, I - IGMP, B - Source Route Bridge ... Device ID Local Intrfce Holdtme Capability Platform Port ID Router Eth 1/1 136 R B Linux Uni Eth 1/1 Layer 3 Switch The last option for routing between VLANs does not involve a router at all. Nor does it involve using a traditional switch. Instead, a different device entirely can be used. This device is known as a Layer 3 Switch or sometimes also as a Multilayer switch. But exactly what is a Layer 3 switch? A Layer 3 Switch is different from a traditional Layer 2 Switch in that it has the functionality for routing between VLANs intrinsically. In fact, when considering how a L3 Switch operates, you can safely imagine that a Layer 3 Switch is a traditional switch with a built in Router. With regard to VLANs the Multilayer switch is configured mostly the same way as a regular L2 switch MultilayerSwitchconfig vlan 20 MultilayerSwitchconfig-vlan name RED MultilayerSwitchconfig vlan 30 MultilayerSwitchconfig-vlan name BLUE MultilayerSwitchconfig interface range eth2/0 - 2 MultilayerSwitchconfig-if-range switchport mode access MultilayerSwitchconfig-if-range switchport access vlan 20 MultilayerSwitchconfig interface range eth3/0 - 2 MultilayerSwitchconfig-if-range switchport mode access MultilayerSwitchconfig-if-range switchport access vlan 30 Then, for each VLAN that you want the Multilayer switch to route for, you have the option of configuring an IP address within what is known as an SVI, or a Switched Virtual Interface. An SVI serves as the L3 termination point for each VLAN – aka, the way in or out of each VLAN. Another way of looking at it is that the SVI serves as the interface on the built-in Router of the Multilayer switch, allowing traffic from one VLAN to reach the built-in Router and be routed to another VLAN as necessary. The configuration for an SVI involves two parts. First, enabling IP Routing; and Second, applying an IP address to the VLAN. To enable IP Routing, use the following command MultilayerSwitchconfig ip routing IP Routing only needs to be enabled once. Some L3 switches come with it enabled by default. Applying the command while it is already enabled will not cause any harm, so if in doubt as to whether it is already enabled or not, simply applying it again is safe. To apply an IP address to the VLANs, configure the SVI as follows MultilayerSwitchconfig interface vlan 20 MultilayerSwitchconfig-if ip address MultilayerSwitchconfig-if no shutdown MultilayerSwitchconfig interface vlan 30 MultilayerSwitchconfig-if ip address MultilayerSwitchconfig-if no shutdown The two configurations above will enable routing between VLAN 20 and VLAN 30. The hosts in each VLAN can use the IP addresses and as their default gateway respectively. When Host A sends a packet to Host B, the packet will be switched within the same VLAN – no L3 processing will occur. When Host A sends a packet to Host C, the packet will be sent to the SVI to be routed to the other VLAN – all regular L3 processing will occur the TTL will be decremented and the L2 header will be rewritten. Multilayer Switch Configuration show runmac address-tablevlan brief MultilayerSwitch show running-config ... ip routing ... interface Vlan20 ip address ! interface Vlan30 ip address MultilayerSwitch show mac address-table Mac Address Table - Vlan Mac Address Type Ports - - - - 20 DYNAMIC Et2/1 20 DYNAMIC Et2/2 30 DYNAMIC Et3/2 30 DYNAMIC Et3/1 Total Mac Addresses for this criterion 4 MultilayerSwitch show vlan brief VLAN Name Status Ports - - - - ... 20 RED active Et2/1, Et2/2 30 BLUE active Et3/1, Et3/2 ip routearpip int brief MultilayerSwitch show ip route Codes L - local, C – connected, ... Gateway of last resort is not set is variably subnetted, 4 subnets, 2 masks C is directly connected, Vlan20 L is directly connected, Vlan20 C is directly connected, Vlan30 L is directly connected, Vlan30 MultilayerSwitch show arp Protocol Address Age min Hardware Addr Type Interface Internet - ARPA Vlan20 Internet 0 ARPA Vlan20 Internet 0 ARPA Vlan20 Internet - ARPA Vlan30 Internet 0 ARPA Vlan30 Internet 0 ARPA Vlan30 MultilayerSwitch show ip interface brief Interface IP-Address OK? Method Status Protocol ... Ethernet2/1 unassigned YES unset up up Ethernet2/2 unassigned YES unset up up ... Ethernet3/1 unassigned YES unset up up Ethernet3/2 unassigned YES unset up up ... Vlan20 YES manual up up Vlan30 YES manual up up Note both sets of tabs and configuration above are from the same device. For the sake of organization, one set of tabs refer to the L3 functions and the other refers to the L2 functions. Summary This article discussed the three different options for Routing between VLANs. In each case, the hosts in communication behave exactly the same. In fact, the hosts have no visibility into how and what they are connected to. Each strategy above has its own benefits and limitations. Hopefully at this point you have a good idea of the options available to enable communication between hosts on different VLANs. ^{Step2. Assign switch ports to the VLANS. Ports fa0/1 and fa0/2 acting as access ports for VLAN10, while ports fa0/3 andfa0/4 for VLAN20.. We shall use fa0/5 port for the trunk port for carrying the traffic between the two VLANS via the router.. NOTE: fa refers to fast ethernet ports used for connecting the network hosts to the switch or router. Configurations for access ports fa0/1 and fa0/2} 1 Define the trunk to use the 802.1q protocol. 2) Set the specific port to trunk mode. 3) Enable the spanning-tree portfast trunk function to ensure the port will forward packets immediately when connected to a device e.g router. Note: The spanning-tree portfast trunk command should never be used on ports that connect to another switch, to .