# Routing updates and path costs

Subject: Computer Networks

Exam: TEE

Reader: https://deep-learning-study-room.vercel.app/cn/#tee/formulas/formulas/routing

Canonical: https://deep-learning-study-room.vercel.app/read/cn/tee/formulas/formulas--routing/

Core units, ALOHA, address and routing rules; illustrative values are practice



$$
d[v]\leftarrow\min(d[v],d[u]+w(u,v))
$$



Old destination distance versus cost to u plus edge u→v.



$$
D_x(y)=\min_{v\in N(x)}\{c(x,v)+D_v(y)\}
$$



Distance vector: local link cost plus neighbour advertisement.



$$
\mathrm{RIP\ metric}=\min(16,\mathrm{link\ cost}+\mathrm{advertisement})
$$



16 represents unreachable. Ordinary hop increments commonly equal 1.

## Learn it with complete solutions

[Full Dijkstra solution](https://deep-learning-study-room.vercel.app/read/cn/tee/read/routing--dijkstra-1/)