Question

Why is a router usually required for devices on separate VLANs to communicate?

Describe the two different ways VLAN ports can be defined. Illustrate each method by providing the two complete commands needed to define a VLAN and its associated ports.

Answer 1

Two separate VLANs must communicate through a layer-3 device, 1ike a router Devices on a VLAN communicate with each other using layer-2. Layer-3 rust be used to communicate between separate layer-2 donains It is clear that hosts on two different VLANs can't directly communicate on a single switch.they using a router Two separate VLANs must corunicate through a layer-3 device, like a router Devices on a LAN communicate with each other using layer-2. Layer-3 rust be used to communicate between separate layer-2 donains Assuming the most common communications (layer-2 ethernet and layer-3 із 1P) when a host on a VLAN wants to communicate with another host on the sane VLAN, it discovers the other hosts layer-2 (e.g. MAC) address with ธ0mething like ARP, and it sends the frame to the MAC addre53 When a host on one VLAN wants to send sonething to a host on another VLAN, it must use a layer-3 (e.g. IP) address The host will use layer-2 to send the franes to its defined gateway (router) The router wi11 strip off the layer-2 frane and inspect the layer-3 packet for the destination layer-3 address The router will then look up the next hop for the layer-3 address It will then create a new layer-2 frame for the layer-3 packet based on the layer-2 LAN on the interface where it needs to send the packet for the next hop Other routers which may be in the path to the end LI vill repeat this process until the frame is placed on the final VLN, where the receiving host gets the frame Two devices on the same VLAN can communicate even if they have different subnet addresses If the two are aware of their MAC adresses. You can define the AC address of a device using ARP command on cormand line of a PC if the device that you're creating VLN'3 on is an L3 device, they can communicate without an external router But if the device 1s an L2 device, you need a router for both the VLAN'3 to communicate

Types of vlan

Types of VLAN's VLAN membership can be classified by 1.port 2.MAC address 3.protocol type. 1) Layer 1 VLAN: Membership by Port Membership in a VLAN can be defined based on the ports that belong to the VLAN. For example, in a bridge with four ports, ports 1, 2, and 4 belong to VIAN 1 and port 3 belongs to VIAN 2 (see below picture) Port VLAN The main disadvantage of this method is that it does not allow for user mobility If a user moves to a different location away from the assigned bridge, the network manager must reconfigure the VLAN. VLAN Port Assignments 1.VLAN3 are assigned to individual switch ports 2.Ports can be statically assigned to a single VLAN or dynamically assigned to a single VLAN. 3.A1l ports are assigned to VLAN 1 by default . Ports are active only if they are assigned to VLANS that exist on the switch. 5.Static port assignments are performed by the administrator and do not change unless modified by the administrator, whether the VLAN exists on the switch or not. 6.Dynamic VLANs are assigned to a port based on the MAC address of the device plugged into a port 7.Dynamic VLAN configuration requires a VLAN Membership Policy Server (vMPS) client, server, and database to operate properly.

Illustrate each method by providing the two complete commands needed to define a VLAN

Configuring Static VLANS: On a Cisco switch, ports are assigned to a single VLA These ports are referred to as access ports and provide a connection for end users or node devices, such as a router or server. By default all devices are assigned to VLAN 1, known as the default VLAN. creating a VLAN, you can manually aasign a port to that VLAN and it will be able to cormunicate only with or through other devices in the VLAN Configure the awitch port for nembership in a given VLA as follows: ●Statically assign a VIAT: C0s:set vian nnber mod/port IOS: (global) interface type mod/port (interface) switchport access vlan number To change the VLA tor a cos device, use the aet vlan cormand, tollowed by the VLNI nurber, and then the port or ports that should be added to that VLAN VIAM ǚ53ignments sch this are considered static because they do not change unle53 the administrator changes the VLAN configuration you must firet select the port (or port range or integrated IOS) and then use the awitchport access vian comand folilowed by the VL^N nurber If the VLAN that the port із азз igned t does not exit in the database, the port ia disabled until the VLAN 1, created. 2.Configuring Dynamic VLAITs static VIANs are the most common form of port VIAN a531gnments, it is possible to have the ฮา¡tch dynamically choose VIAT based on the MAC addre53 of the device connected to ǖ port Io achieve this, you mmt he a VIP database file, a VI server, a VI ciient awitch, and a dynamic port After you have properly configured these components, a dynamic port can choose the VLAN based on whichever device is connected to that port.

г.configuring D 3tatic VLAlla are the most common form of port-LAN a331annenta, tュ3 po33ible to have the N1tch dynamically choose a To achieve this, you rust have a VIP database ile, a VIP server, a VIP client awitch, and a dynaric port. After you have properly configured these co ponents, a dynamic port can choose the VLAN based on whichever device is connected to that port Use the following steps to configure dynanic VLANS: 71 72 ynanic VLANS N baaed on the MAC addre33 of the device connected to a port 74 76 1.Create a VIP database file 7 7 uaing a text editor, such as WordPad or v, ceate a VIP database rile and place it on a VMPS o Remote Copy Protocol (RCP) eer. The VIP databae ile contains the following elements: 79 1.A header that includes a VMPS domain nane 80 2. 81 3.The fallbacKVIAu name 82 4.A list of MAC address napped to VLAN nanes 83 The basic outline of a VHPS database file is as follows: 84 vps dorain Switchblock1 The VMPS operational rode pe mode open 6 vps fellback default 87 vrps no-domain-rea deny 89 pB-mac-addrs 91 address 0001.0387.0943 vlan-name GroupA 92 addreas 0050.04 93 addreas 0050.DABF.1134 vlan-name Groupc 94 The very first thing that should be in the VIF database file are the letters vnps followed by the word domain and a domain nae 91.9950 vlan-name GroupB The domain name matches that of the VTP domain nane of the switch(es) sending the MPS request. くVIP 13 discussed further in 3ect10η "6-4: ylaN Irunking Protocol.*) Th13 name is used in the request for VMPS mapping information lhe next three linea 1n the t11e are 1nformation about h0ผ VMPS ahould operate. The mode open ındicates whether a request comes in that is not in the Ma address 11a 96 98 . The switch should place that device in a default VIA. The next line specifies that ur by name. The name default is that o,VIAr . 99 You can also configure the mode as closed: if this is the case, the port will be suspended if the device is not in the MAC address table 100 The no-domain-req deny option atatea that any device that aenda a requeat with no domain nane ahould not be given any port VLAN mapping inforration 101 Each (exclamation point) 1 a corent and 1s ignored by the VMPS aerver The vmps-nac-addrs entry indicates the start of the Mc addres to VLA!I rapping- the VIAII name 1, the exact name (including case} аз found in the VLAN database of the requesting ธwitch. If the nae is not found on the local switeh, the assignment ia not made. 103 The entries are entered with the format addreas address vlan-nane vlan_name, where the address is in dotted-hexadecimal format, 105 When a request 13 3ent, this rapping 13 returned to the requesting awitch. The VN a331gnment 13 based on the name returned