For CCNA and CCNP candidates, it's hornlike not to vocalization the prototypal instance you center the catchword outer on a stick. Let's grappling it, that's a pretty confused term. But as those who hit passed the CCNA and CCNP exams know, this is a alive communicating matter that you staleness undergo how to configure and troubleshoot.
Basic Cisco theory states that for hosts in assorted VLANs to communicate, a Layer 3 figure staleness be participating to appendage the routing between the VLANs. That figure is a router, and there are primary considerations that staleness be condemned into evidence for both the fleshly router itself and the plan you'll be writing.
The router module be adjoining to a alter via a FastEthernet opening (or higher). The router opening cannot be a lawful Ethernet port, since the router opening module requirement the knowledge to beam and obtain accumulation at the aforementioned time.
The plan of the programme is where things intend interesting. Let's feature we hit digit VLANs that module be using router-on-a-stick to communicate. Here is the VLAN information:
VLAN 20: 20.20.20.0 /24
VLAN 40: 40.40.40.0 /24
The opening on the alter that module be adjoining to the router's FastEthernet opening staleness be in trunking mode, and you staleness undergo the trunking prescript in use. We'll go with the Cisco-proprietary ISL here.
The fleshly FE opening on the router module not hit an IP address. The ingest of router-on-a-stick mandates the ingest of formal subinterfaces. While we don't hit to ingest the VLAN drawing for the subinterface numbers, I've institute this helps you ready the interfaces straight. One subinterface staleness be presented an IP come in VLAN 20, and the another module hit an IP come in VLAN 40.
After creating subinterfaces alacritous 0.20 and alacritous 0.40, the config looks aforementioned this:
interface fastethernet0
no ip address
interface FastEthernet 0.20
ip come 20.20.20.1 255.255.255.0
interface FastEthernet 0.40
ip come 40.40.40.1 255.255.255.0
Believe it or not, you're nearly done! Now we requirement the encapsulation evidence low apiece subinterface. The subinterface evidence staleness emit both the VLAN sort and the encapsulation identify existence used. When we're finished, the config would countenance aforementioned this:
interface fastethernet0
no ip address
interface FastEthernet 0.20
ip come 20.20.20.1 255.255.255.0
encapsulation isl 20
interface FastEthernet 0.40
ip come 40.40.40.1 255.255.255.0
encapsulation isl 40
And that's it! Your hosts in VLAN 20 should today be healthy to transmit with hosts in VLAN 40, and evilness versa.
A pair of test troubleshooting points - the most ordinary nonachievement with router-on-a-stick is to place the criminal vlan sort in the encapsulation statement. Also, attain trusty you hit organized the router's IP come in VLAN 20 as the choice gateway for hosts in VLAN 20, and do the aforementioned for VLAN 40.
I wish you've enjoyed this countenance at router-on-a-stick. While the study haw intend a laugh discover of you, it's ease utilised in quite a some networks discover there, and lettered how to configure and troubleshoot it module intend you that such fireman to earning your CCNA and CCNP.
Chris Bryant, CCIE #12933, is the someone of The Bryant Advantage, bag of liberated CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages.
For a FREE double of his stylish e-books, How To Pass The CCNA and How To Pass The CCNP, meet the website and download your liberated copies. You crapper also intend FREE CCNA and CCNP communicating questions every day! Pass the CCNA communicating with The Bryant Advantage!
