Core Size

Core Size
Routing protocols are the main factor in determining the size of your core. This is because
routers, or any layer 3 device, isolate the core. Routers send updates to other routers, and
as the network grows, so do these updates, so it takes longer to converge or to have all the
routers update. Because at least one of the routers will connect to the Internet, it’s possible
that there will be more updates throughout the internetwork.
The routing protocol dictates the size of the distribution layer devices that can communicate
with the core. Table 12.2 shows a few of the more popular routing protocols and the number
of blocks each routing protocol supports. Remember that this includes all blocks, including
server, mainframe, and WAN.