0
We kick off the CCNA series from the beginning. Operation of IP data networks is weighted as 5% in the CCNA RS blueprint. The first topic is:
1.1 Recognize the purpose and functions of various network devices such as routers, switches, bridges and hubs
Router
A router is a device that routes between different networks, meaning that it looks at the IP header and more specifically the destination IP of a packet to do forwarding. It uses a routing table which is populated by static routes and routes from dynamic protocols such as RIP, EIGRP, OSPF, ISIS and BGP. These routes are inserted into the Routing Information Base (RIB). The routes from different sources compete against each other and the best route gets inserted into the RIB. To define how trustworthy a route is, there is a metric called Administrative Distance (AD). These are some of the common AD values:
0 Connected route
1 Static route
20 External BGP
90 EIGRP
110 OSPF
115 ISIS
120 RIP
200 Internal BGP
255 Don't install
If a value of 255 is used, the route will not installed in the RIB as the route is deemed not trustworthy at all.
The goal Continue reading