For CCNA and CCNP candidates, it’s difficult not to chuckle the first time you listen to the phrase “router over a stick”. Permit’s experience it, that’s a reasonably foolish time period. But as all those who have handed the CCNA and CCNP exams know, this is the essential Examination topic that you should understand how to configure and troubleshoot.
Primary Cisco principle states that for hosts in several VLANs to communicate, a Layer 3 gadget has to be included to manage the routing amongst the VLANs. That system is often a router, and you'll find Distinctive things to consider that needs to be taken under consideration for both the Bodily router itself and also the configuration you’ll be producing.
The router will likely be linked to a change by means of a FastEthernet port (or increased). The router port can not be an everyday Ethernet port, since the router port will require the chance to ship and get info simultaneously.
The configuration on the interface is in which issues get fascinating. Let’s say Now we have two VLANs which will be using router-on-a-stick to speak.
Here's the VLAN details:
VLAN 20: 20.twenty.20.0 /24
VLAN forty: forty.40.forty.0 /24
The port around the change that should be linked to the router’s FastEthernet port have to be in 안전공원 trunking method, and you must know the trunking protocol in use. We’ll go Together with the Cisco-proprietary ISL here.
The physical FE port around the router will likely not have an IP deal with. The use of router-on-a-stick mandates the use of reasonable subinterfaces. Whilst we don’t have to make use of the VLAN figures to the subinterface quantities, I’ve located this helps you keep the interfaces straight. http://query.nytimes.com/search/sitesearch/?action=click&contentCollection®ion=TopBar&WT.nav=searchWidget&module=SearchSubmit&pgtype=Homepage#/토토사이트 Just one subinterface must be provided an IP deal with in VLAN twenty, and the opposite may have an IP deal with in VLAN 40.
Just after producing subinterfaces rapid 0.twenty and rapid 0.forty, the config appears like this:
interface fastethernet0
no ip handle
interface FastEthernet 0.twenty
ip deal with twenty.twenty.20.1 255.255.255.0
interface FastEthernet 0.40
ip deal with 40.forty.forty.1 255.255.255.0
Truth be told, you’re Just about completed! Now we'd like the encapsulation statement underneath Each individual subinterface. The subinterface statement ought to mirror both equally the VLAN range and the encapsulation style being used. After we’re finished, the config would appear like this:
no ip deal with
ip tackle twenty.20.twenty.1 255.255.255.0
encapsulation isl twenty
ip address forty.forty.40.one 255.255.255.0
encapsulation isl forty
Which’s it! Your hosts in VLAN 20 should really now be capable of communicate with hosts in VLAN 40, and vice versa.
A few final troubleshooting details – the commonest mistake with router-on-a-stick is To place the incorrect vlan selection during the encapsulation statement. Also, ensure that you have configured the router’s IP tackle in VLAN 20 as being the default gateway for hosts in VLAN 20, and do the identical for VLAN forty.
I hope you’ve appreciated this evaluate router-on-a-stick. Though the name may get a chuckle out of you, it’s however Employed in quite a few networks on the market, and knowing the best way to configure and troubleshoot it will get you that Considerably nearer to earning your CCNA and CCNP.