網路原理(一) Section 6.2

netstat -r  ;  route print
Entering the netstat -r command or the equivalent route print command, displays three sections related to the current TCP/IP network connections

interface list
Lists the Media Access Control (MAC) address and assigned interface number of every network-capable interface on the host, including Ethernet, Wi-Fi, and Bluetooth adapters.

IPv4 Route Table
Lists all known IPv4 routes, including direct connections, local network, and local default routes.

IPv6 Route Table
Lists all known IPv6 routes, including direct connections, local network, and local default routes.

directly-connected routes
These routes come from the active router interfaces. Routers add a directly connected route when an interface is configured with an IP address and is activated.

remote routes
These routes come from remote networks connected to other routers. Routes to these networks can be manually configured on the local router by the network administrator or dynamically configured by enabling the local router to exchange routing information with other routers using a dynamic routing protocol.

default route
Like a host, routers also use a default route as a last resort if there is no other route to the desired network in the routing table. 

show ip route
On a Cisco IOS router, the show ip route command can be used to display the router’s IPv4 routing table.

route source
Notice how directly connected networks with a route source of C and L have no next-hop address. This is because a router can forward packets directly to hosts on these networks using the designated interface.

destination network
When a packet arrives at the router interface, the router examines the packet header to determine the destination network.

outgoing interface
The switch looks up the destination MAC address in its switching table, determines the outgoing interface port, and forwards the frame onto its destination through the designated switch port.

administrative distance
行政距離

metric
If there are two or more possible routes to the same destination, the metric is used to decide which route appears in the routing table.

next-hop
If a match is found, the router forwards the packet to the next hop address out of the identified interface.

route timestamp
路由時間戳記

branch routers
Teleworkers, small businesses, and medium-size branch sites. Includes Cisco Integrated Services Routers (ISR) G2 (2nd generation).

WAN routers
Large businesses, organizations, and enterprises. Includes the Cisco Catalyst Series Switches and the Cisco Aggregation Services Routers (ASR).

service proivder routers
Large service providers. Includes Cisco ASR, Cisco CRS-3 Carrier Routing System, and 7600 Series routers.