Router-on-a-stick (ROAS) could be an approach to link a router with one individual physical link to handle and execute IP routing among VLANs. Through the switch’s outlook, A physical link is drawn as a trunk port permitting all VLANs that proceed to be routed. Coming from the router’s viewpoint, another physical intersection is constituted as numerous effective sub-alliances, individual for every VLAN. An IP address along with every VLAN is then designed on every sub-articulation and the router executes IP routing connecting linked networks.
Introduction
The router on a stick is distinctive in all the ways that permit routing linking VLANs. That sort of arrangement includes a router association besides a switch attached between one local area network connection customized as an 802.1q trunk connection. Including an arrangement that is basically in connections wherever no layer-3 control endures. Yet initially, let’s discover what it is like. Once configuring the latest Virtual LANs on switch ports, we tend to split the telecast domain during which it was settled into compact Virtual LAN-limited components. The essential switch can not direct messages among broadcast domains. It is well known that the router is a device that routes packets and separates broadcast provinces.
The layer three OSI model compound is, further, needed to permit transmission among devices from completely different Virtual LANs. An example could be a router on a stick we’ll enfold during this given material, however, there are also solutions like SVI known as a virtual switch interface or a router interface per Virtual LAN.
The sub-intersection could be a key characteristic of the router on a stick. It is organized for every connection on the router.
Sub-intersections are the logical components of a physical configuration. Because of this method, it is not required to use N physical intersections of the router on N Virtual LANs. Rather, there is a trunk connection in the middle of a switch and a router, thus marked messages went to the router. Following that, the router discards the labels and broadcasts the routing channel.
This is essential to arrange up 802.1Q summarization on every sub-intersection and paralleling the Virtual LAN marked in addition as a result of once matching the entry, the packet is summarized in line with the process organized on the output intersection.
Physical Diagram
Manifest in the diagram below is our physical choreography for a given instance. Note there is just one physical connection between the switch and the router which can be used for all Virtual LANs. Contrast this choreography to the one from the earlier lesson, where there was a physical connection for each Virtual LAN.
Configuration of Switch
The foremost step is to make the desired 2 Virtual LANs on your Cisco switch and assemble them with an IP address. Since all Cisco switches hold Virtual LAN1, we tend to create Virtual LAN2:
Switch A# configure terminal
Switch B(configure)# virtual LAN2
Switch C(configure-virtual LAN)# name voice
Switch D(configure-virtual LAN)# exit
Switch E(configure)# interface virtual lan1
Switch F(configure-if)# description Data Virtual LAN
Switch G(configure-if)# ip address 192.168.0.2 255.255.255.0
Switch H(configure-if)# exit
Switch I(configure)# interface virtual LAN2
Switch J(configure-if)# description Voice Virtual LAN
Switch K(configure-if)# ip address 192.168.2.2 255.255.255.0
Switch L(configure-if)# exit
After that, we like to make the trunk port that may link with the router. For this cause, we’ve chosen port GigabitEthernet 0/1 (port 1):
SWITCH 1# configure terminal
SWITCH 1(configure)# interface gigabitethernet 0/1
SWITCH 1(configure-if)# description Trunk-to-Router
SWITCH 1(configure-if)# switchport trunk encapsulation dot1q
SWITCH 1(configure-if)# switchport mode trunk
SWITCH 1(configure-if)# spanning-tree portfast trunk
To remove uncertainty, these steps are directing the switch thus:
- Describe the trunk to utilize the 802.1q protocol
- Put down the particular port-to-trunk method
- Authorized the spanning-tree portfast trunk function to confirm the port will forward messages straight away when linked to a router system. Note: The spanning-tree portfast trunk instruction should never be utilized on ports that are linked to some other switch, so authorized connection loops are eschewed.
The above-mentioned steps complete the switch-side configuration.
Configuration of Router on a Stick
Switches split up the transmit domain between Virtual LAN. Virtual LAN is a divided transmit domain from one transmit domain. The switch doesn’t move ahead messages over divergent Virtual LANs by themselves. If we wish to form these virtual LANs to converse with one another, The idea of putting away Virtual LAN Routing is second-hand.
Entomb Virtual LAN Routing:
Entomb Virtual LAN routing is a method during which we tend to have different virtual LANs make contact with one another regardless of wherever the Virtual LANs are found either on the same switch or a different switch. once the bury Virtual LAN Routing will be attained between a layer-3 device i.e. Router or layer-3 Switch. Virtual LAN Routing is referred to as a Router on a stick.
Router On a Stick:
The Router on a stick terminal is further split up into sub-terminals, which act as a default entry to their various Virtual LANs.
This is a topology within which there is a router and a switch and a few final hosts. Two distinct Virtual LANs have been generated on the switch. The router’s terminal is sliced up into two sub-interfaces or two different Virtual LANs which can act as an offensive entrance to their several Virtual LANs. Then the router will execute Virtual LAN Routing and also the Virtual LANs can interface with one another.
Initially, we are going to allocate the IP address to the host PC1 as 192.168.1.10/24, Server 192.168.1.20/24, and also the alternative host PC2 can have IP address 192.168.2.10/24 standard.
Now, we are going to create sub-terminals of fa0/0 as fa0/0.1 and fa0/0.2 and allocate IP addresses as 192.168.1.1/24 and 192.168.2.1/24 severally on the router’s ports.
ROUTER A# int fa0/0.1
ROUTER A# encapsulation dot1q 2
ROUTER A# ip address 192.168.1.1 255.255.255.0
ROUTER A# int fa0/0.2
ROUTER A# encapsulation dot1q 3
ROUTER A# ip address 192.168.2.1 255.255.255.0
Here encapsulation type dot1q is utilized for frame labelling among the given two distinctive Virtual LANs. When the switch Ahead sends a message from one Virtual LAN to another one, it pushes a Virtual LAN into the Ethernet header.
Further, we will make two distinct Virtual LANs on the switch knowingly Virtual LAN 2 and Virtual LAN 3 assign the names dept_no and dept_name.
SW 1# virtual LAN 2
SW 1# name dept_no
SW 1# virtual LAN 3
SW 1# name dept_name
SW 1# int range fa0/1-2
SW 1# switchport mode access
SW 1# switchport access virtual LAN 2
SW 1# int fa0/3
SW 1# switchport mode access
SW 1# switchport access Virtual LAN 3
Now, we have allocated Virtual LAN 2 to the particular switch ports fa0/1, fa0/2 and vlan 3 to fa0/3 correspondingly.
Applications of Router on a Stick
Instances, wherever this arrangement is utilized, may be found in servers committed for prints, files, or for separating into completely discrete sections. An example of the router on a stick usage is found in Decision Manager Specific installation once the Voice above the IP connection and Cisco IP mobile devices have a requirement to separate. Pursuit networks apply this methodology of segregating servers to stop all clients from ‘possessing similar access benefits to resources.
Advantages and Disadvantages of Router on a Stick
Advantages:
- Networks that make use of a router on a stick profit from only needing a single LAN(Local Area Network) interrelation to be utilized for multiple Virtual LANs, that is. The figure for Virtual LANs is not restricted by the quantity of LAN ports accessible. The division of network relationships does not answer to the physical spot of the ports on the router. Consequently, this detaches the necessity for multiple cable and wiring administrations.
- While Virtual LANs are separated, it decreases the amount of traffic flow through an affiliation. Separating Virtual LAN supplies increased network security. Network directors have direct management over multiple transmit domains. In the process of a venomous user trying to access any switch port, they will have restricted access to the system. The segmentation serves to limit responsive traffic that moves at an enterprise.
- Precise cases where peer-to-peer are to be generated. Users’ need for a high level of security can be isolated from different systems. That outside of the Virtual LANs cannot transmit, thus departments are created independently from one another. Also, third-party users cannot approach the network simply. Networks via a router on a stick are self-supporting of their physical positions, thus reactive data can be grasped without understanding and with ease.
- Modifications to networks like adding or removing a transmit domain are accomplishable by distributing hosts to acceptable Virtual LANs. Transmits of networks can be controlled by multiple hosts and managed by implementing several Virtual LANs as needed. Therefore, this will increase the figure of networks while at the same time decreasing their size.
- Execution of this arrangement only needs one router.
Disadvantages:
- Compared to the choice of mistreatment L3 (Layer 3 switching), the trunk could become a supply of obstruction as traffic from all Virtual LANs should move between the trunk link. Trendy connections utilize the L3 switch which supplies larger bandwidth measures and practices. As all connection traffic travels through the trunk double, the trunk will become an important supply of congestion, as there is only one trunk association. The bottleneck is often alleviated if one intersection is joined with an alternative intersection via link accumulation.
- If the router fails, there is no backup which could behave like a bottleneck within the system. Since all VLANs should traverse one router, there is excellent potential for poor bandwidth measures assuming for all network connections.
- Before execution of inter-VLAN routing into the network, it needs further configuration and virtual application. Further latency could also be elicited once the switch to the router.
- Layer three switches will route traffic to alternative switches while not the requirement for a router. It processes information packets quicker than routers since the data cross-wire speed. Trendy switches have information measure ports with larger limits that may enhance the performance of the system.
Conclusion
- This article concisely mentioned the technology and method behind the Router-on-a-stick and revealed how you can configure an 802.1Q trunk link between a Cisco router and switch.
- The Router-on-a-stick configuration is generally utilized in environments where there is no layer 3 switching as a result it provides inter-VLAN routing services utilizing a single router and one interface, making it cost-efficient.
- We can only make connection changes by allocating the authentic hosts to the mandatory VLANs along with the configure-if switchport mode.
