# 4/21 Network Protocols

## Spanning Tree Algorithm

Max/Min

find shortest path for


## Virtual Circuit Services – Multi-Protocol Label Switching (MPLS)

## Routing vs. Forwarding


Routing: use algorith,like Dijkstra,

Routing refers to the network-wide algorithm,like Dijkstra, that determines end-to-end paths that packets take from source to destination.

Forwarding refers to the router-local action of transferring the packet from an input link interface to the output link interface.

## DHCP

Getting IP Addresses for Host Network Interfaces

## ARP (Address Resolution Protocol) packet

work in LAN,

ARP send a broadcast message to ask the subject question for every host and host reply to the sender’s MAC address

can cache the IP address

:::info
Who has ip ......?
:::

走過會建立在ARP table中，下次可以從中查詢要走哪一個interface即可

## Path MTU Discovery （最佳化package size）

## IPv4 Fragmentation

packet太大，需要切碎，依照MTU切

## Path MTU Discovery


## ICMP message

:::info
ping ...
traceroute ...
:::


更正：`Time exec...`>>`TTL`

## Tracerouth

## IPv6 transver

# Routing

## shortest path

## shortest path protocal