power on self-test (POST)
First, the switch loads a power-on self-test (POST) program stored in ROM. POST checks the CPU subsystem. It tests the CPU, DRAM, and the portion of the flash device that makes up the flash file system.
boot loader
The boot loader performs low-level CPU initialization. It initializes the CPU registers, which control where physical memory is mapped, the quantity of memory, and its speed.
boot environment variable
In the figure, the BOOT environment variable is set using the boot system global configuration mode command.
boot system
show boot
mode button
system led
boot loader switch:
dir flash:
redundant power system (RPS) LED
port status LED
port duplex LED
port speed LED
power over ethernet (POE) LED
switch virtual interface (SVI)
VLAN
虛擬區域是一種建構於區域網路交換技術的網路管理的技術，網管人員可以藉此透過控制交換器有效分派出入區域網的封包到正確的出入埠，達到對不同實體區域網中的裝置進行邏輯分群管理，並降低區域網內大量資料流通時，因無用封包過多導致壅塞的問題，以及提昇區域網的資訊安全保障。
full-duplex
全雙工（full-duplex）的系統允許二台設備間同時進行雙向資料傳輸。 一般的電話、手機就是全雙工的系統，因為在講話時同時也可以聽到對方的聲音。 全雙工的系統可以用一般的雙向車道形容。 兩個方向的車輛因使用不同的車道，因此不會互相影響。
half-duplex
半雙工（half-duplex）的系統允許二台設備之間的雙向資料傳輸，但不能同時進行。 因此同一時間只允許一設備傳送資料，若另一設備要傳送資料，需等原來傳送資料的設備傳送完成後再處理。
auto-mdix
Using the automatic medium-dependent interface crossover (auto-MDIX)
feature on an interface eliminates this problem. When auto-MDIX is
enabled, the interface automatically detects the required cable
connection type (straight-through or crossover) and configures the
connection appropriately.
interface vlan 99
ip default-gateway
show ip interface brief
duplex auto
speed auto
mdix auto
show interfaces
input errors
runts
giants
CRC error
output errors
collisions
Collisions in half-duplex operations are normal. However, you should never see collisions on an interface configured for full-duplex communication.
late collisions
A late collision refers to a collision
that occurs after 512 bits of the frame have been transmitted. Excessive
cable lengths are the most common cause of late collisions.
2018年11月30日 星期五
2018年11月26日 星期一
網路原理(一) RSE6 Section 3.3
classful routing
The routing table hierarchy in Cisco IOS was originally implemented with the classful routing scheme.
classless addressing
Although the routing table incorporates both classful and classless addressing, the overall structure is still built around this classful scheme.
route source (C and L)
Identifies how the route was learned. Directly connected interfaces have two route source codes. C identifies a directly connected network. Directly connected networks are automatically created whenever an interface is configured with an IP address and activated. L identifies that this is a local route. Local routes are automatically created whenever an interface is configured with an IP address and activated.
destination network
The address of the remote network and how that network is connected.
outgoing interface
Identifies the exit interface to use when forwarding packets to the destination network.
administrative distance (AD)
Identifies the trustworthiness of the route source. The AD for static routes is 1 and the AD for connected routes is 0. Dynamic routing protocols have an AD higher than 1 depending upon the protocol.
metric
dentifies the value assigned to reach the remote network. Lower values indicate preferred routes. The metric for static and connected routes is 0.
route timestamp
Identifies from when the route was last heard.
ultimate route
An ultimate route is a routing table entry that contains either a next-hop IPv4 address or an exit interface. Directly connected, dynamically learned, and local routes are ultimate routes.
level 1 route
A level 1 route is a route with a subnet mask equal to or less than the classful mask of the network address.
level 1 parent route
A parent route is a level 1 network route that is subnetted. A parent route can never be an ultimate route.
level 2 child route
A level 2 child route is a route that is a subnet of a classful network address.
network route
A network route that has a subnet mask equal to that of the classful mask.
supernet route
A supernet route is a network address with a mask less than the classful mask, for example, a summary address.
default route
A default route is a static route with the address 0.0.0.0/0.
The routing table hierarchy in Cisco IOS was originally implemented with the classful routing scheme.
classless addressing
Although the routing table incorporates both classful and classless addressing, the overall structure is still built around this classful scheme.
route source (C and L)
Identifies how the route was learned. Directly connected interfaces have two route source codes. C identifies a directly connected network. Directly connected networks are automatically created whenever an interface is configured with an IP address and activated. L identifies that this is a local route. Local routes are automatically created whenever an interface is configured with an IP address and activated.
destination network
The address of the remote network and how that network is connected.
outgoing interface
Identifies the exit interface to use when forwarding packets to the destination network.
administrative distance (AD)
Identifies the trustworthiness of the route source. The AD for static routes is 1 and the AD for connected routes is 0. Dynamic routing protocols have an AD higher than 1 depending upon the protocol.
metric
dentifies the value assigned to reach the remote network. Lower values indicate preferred routes. The metric for static and connected routes is 0.
route timestamp
Identifies from when the route was last heard.
ultimate route
An ultimate route is a routing table entry that contains either a next-hop IPv4 address or an exit interface. Directly connected, dynamically learned, and local routes are ultimate routes.
level 1 route
A level 1 route is a route with a subnet mask equal to or less than the classful mask of the network address.
level 1 parent route
A parent route is a level 1 network route that is subnetted. A parent route can never be an ultimate route.
level 2 child route
A level 2 child route is a route that is a subnet of a classful network address.
network route
A network route that has a subnet mask equal to that of the classful mask.
supernet route
A supernet route is a network address with a mask less than the classful mask, for example, a summary address.
default route
A default route is a static route with the address 0.0.0.0/0.
網路原理(一) RSE6 Section 3.2
以下都為Cisco設備指令，就不一一說明
router rip
no router rip
network network-address
show ip protocols
show ip route
version 2
no version
no auto-summary
passive-interface
passive-interface default
no passive-interface
ip route 0.0.0.0 0.0.0.0
default-information originate
router rip
no router rip
network network-address
show ip protocols
show ip route
version 2
no version
no auto-summary
passive-interface
passive-interface default
no passive-interface
ip route 0.0.0.0 0.0.0.0
default-information originate
網路原理(一) RSE6 Section 3.1
Static routing
靜態路由，一種路由的方式，路由項由手動配置，而非動態決定。與動態路由不同，靜態路由是固定的，不會改變，即使網路狀況已經改變或是重新被組態。一般來說，靜態路由是由網路管理員逐項加入路由表。
Dynamic routing
動態路由（Dynamic Route）就不須要手動輸入，較屬於Worry-Free的類型，一切的工作都交給路由器設備之間去協調，互相交換並學習這些資料，管理人員只要做Routing Protocol的設定即可。這種方式比較耗費系統資源，速度也稍微慢一些，因為系統需要時間去做學習的動作，也需要一點時間才能把Routing Table建立得比較完整。不過，好處是一旦網路架構有任何的改變，網路管理人員不須要做太多事情來管理並且維護Routing Table。
RIPv1
RIP的英文全稱是「Routing Information Protocol」，該路由協定是採用Distance Vector路由演算法之一，是一個相當著名的路由協定，因為RIP路由協定使用得相當廣泛。
RIPv2
RIP路由協定又分為RIPv1和RIPv2兩個版本，這兩個版本的RIP路由協定不盡相同。其中，RIPv1路由協定屬於Classful路由協定，RIPv2則屬於Classless的路由協定，也因為如此，RIPv1路由協定不會傳送子網路遮罩，RIPv2路由協定則會在更新路由資訊時傳送子網路遮罩。也因為沒有子網路遮罩的資訊，RIPv1路由協定無法支援不定長度子網路遮罩，而RIPv2路由協定提供支援。在傳送的方式上，RIPv1使用廣播（Broadcast）的方式傳送路由資訊更新，而RIPv2路由協定使用群播（Multicast）的方式來傳送，其所使用的群播位址是224.0.0.9。
OSPF
開放式最短路徑優先（英語：Open Shortest Path First，縮寫為OSPF）是對鏈路狀態路由協定的一種實現，隸屬內部網路關協定（IGP），故運作於自治系統內部。
IS-IS
中間系統到中間系統（IS-IS，Intermediate system to intermediate system，讀作「i-sys」）是一種內部網路關協定，是電信業者普遍採用的內部網路關協定之一。 標準的IS-IS協定是由國際標準化組織制定的ISO/IEC 10589:2002 所規範的。
IGRP
在眾多的通訊協定中，IGRP是其中一種IGP（Interior Gateway Protocol）協定。 有所謂的IGP，當然也就有EGP（Exterior Gateway Protocol），兩者差異在於自治系統（Autonomous System，AS）。
EIGRP
在內部網路關路由協定（IGRP）的基礎上，由思科公司發展而成，於2013年Cisco將此標準公開，不再是私有的路由協定，在同樣。 EIGRP是一種進階距離向量路由協定（也稱混合型路由協定）。
BGP
邊界閘道器協定（英文：Border Gateway Protocol, BGP）是網際網路上一個核心的去中心化自治路由協定。 它通過維護IP路由表或『字首』表來實現自治系統（AS）之間的可達性，屬於向量路由協定。
routing table
在計算機網絡中，路由表（routing table）或稱路由擇域信息庫（RIB, Routing Information Base），是一個存儲在路由器或者聯網計算機中的電子表格（文件）或類資料庫。
stub network
stub network指的是只能透過單一路由路徑連接的網路，因此有時候也稱為leaf node。
update messages
Static routes do not send update messages
靜態路由，一種路由的方式，路由項由手動配置，而非動態決定。與動態路由不同，靜態路由是固定的，不會改變，即使網路狀況已經改變或是重新被組態。一般來說，靜態路由是由網路管理員逐項加入路由表。
Dynamic routing
動態路由（Dynamic Route）就不須要手動輸入，較屬於Worry-Free的類型，一切的工作都交給路由器設備之間去協調，互相交換並學習這些資料，管理人員只要做Routing Protocol的設定即可。這種方式比較耗費系統資源，速度也稍微慢一些，因為系統需要時間去做學習的動作，也需要一點時間才能把Routing Table建立得比較完整。不過，好處是一旦網路架構有任何的改變，網路管理人員不須要做太多事情來管理並且維護Routing Table。
RIPv1
RIP的英文全稱是「Routing Information Protocol」，該路由協定是採用Distance Vector路由演算法之一，是一個相當著名的路由協定，因為RIP路由協定使用得相當廣泛。
RIPv2
RIP路由協定又分為RIPv1和RIPv2兩個版本，這兩個版本的RIP路由協定不盡相同。其中，RIPv1路由協定屬於Classful路由協定，RIPv2則屬於Classless的路由協定，也因為如此，RIPv1路由協定不會傳送子網路遮罩，RIPv2路由協定則會在更新路由資訊時傳送子網路遮罩。也因為沒有子網路遮罩的資訊，RIPv1路由協定無法支援不定長度子網路遮罩，而RIPv2路由協定提供支援。在傳送的方式上，RIPv1使用廣播（Broadcast）的方式傳送路由資訊更新，而RIPv2路由協定使用群播（Multicast）的方式來傳送，其所使用的群播位址是224.0.0.9。
OSPF
開放式最短路徑優先（英語：Open Shortest Path First，縮寫為OSPF）是對鏈路狀態路由協定的一種實現，隸屬內部網路關協定（IGP），故運作於自治系統內部。
IS-IS
中間系統到中間系統（IS-IS，Intermediate system to intermediate system，讀作「i-sys」）是一種內部網路關協定，是電信業者普遍採用的內部網路關協定之一。 標準的IS-IS協定是由國際標準化組織制定的ISO/IEC 10589:2002 所規範的。
IGRP
在眾多的通訊協定中，IGRP是其中一種IGP（Interior Gateway Protocol）協定。 有所謂的IGP，當然也就有EGP（Exterior Gateway Protocol），兩者差異在於自治系統（Autonomous System，AS）。
EIGRP
在內部網路關路由協定（IGRP）的基礎上，由思科公司發展而成，於2013年Cisco將此標準公開，不再是私有的路由協定，在同樣。 EIGRP是一種進階距離向量路由協定（也稱混合型路由協定）。
BGP
邊界閘道器協定（英文：Border Gateway Protocol, BGP）是網際網路上一個核心的去中心化自治路由協定。 它通過維護IP路由表或『字首』表來實現自治系統（AS）之間的可達性，屬於向量路由協定。
routing table
在計算機網絡中，路由表（routing table）或稱路由擇域信息庫（RIB, Routing Information Base），是一個存儲在路由器或者聯網計算機中的電子表格（文件）或類資料庫。
stub network
stub network指的是只能透過單一路由路徑連接的網路，因此有時候也稱為leaf node。
update messages
Static routes do not send update messages
2018年11月15日 星期四
網路原理（一） RSE6 Section 2.3
extended ping
An extended ping is an enhanced version of the ping utility. Extended ping enables you to specify the source IP address for the ping packets.
An extended ping is an enhanced version of the ping utility. Extended ping enables you to specify the source IP address for the ping packets.
網路原理（一）RSE6 Section 2.2
exit-intf
next hop
recursive static route
recursive lookup
directly connected static route
CEF (Cisco Express Forwarding)
FIB (Forwarding Information Base)
fully specified statci route
edge router
stub router
quad-zero route
::/0
destination network
Fully specified static IPv6 route
IPv4 Static Host Routes
IPv6 Static Host Routes
以下為Cisco設備指令
IPv6 route
show ipv6 route
show ipv6 route static
show ipv6 route network
next hop
recursive static route
recursive lookup
directly connected static route
CEF (Cisco Express Forwarding)
FIB (Forwarding Information Base)
fully specified statci route
edge router
stub router
quad-zero route
::/0
destination network
Fully specified static IPv6 route
IPv4 Static Host Routes
IPv6 Static Host Routes
以下為Cisco設備指令
IPv6 route
show ipv6 route
show ipv6 route static
show ipv6 route network
網路原理（一） RSE6 Section 2.1
static route
A network administrator can manually configure a static route to reach a specific network. Unlike a dynamic routing protocol, static routes are not automatically updated and must be manually reconfigured any time the network topology changes.
administrative distance (AD)
is a measure of the preference of route sources. Route sources with low AD values are preferred over routes sources with higher AD values.
stub network
Routing to and from stub networks. A stubnetwork is a network accessed by a single route, and the router has only one neighbor.
default route
Using a single default route to represent a path to any network that does not have a more specific match with another route in the routing table. Default routes are used to send traffic to any destination beyond the next upstream router.
default static route ; 0.0.0.0/0
A default static route is simply a static route with 0.0.0.0/0 as the destination IPv4 address.
Gateway of Last Resort
A default route is used when no other routes in the routing table match the destination IP address of the packet. In other words, if a more specific match does not exist, then the default route is used as the Gateway of Last Resort.
more specific match
When no other routes in the routing table match the packet destination IP address. In other words, when a more specificmatch does not exist. A common use is when connecting a company's edge router to the ISP network.
summary static route
To reduce the number of routing table entries, multiple static routes can be summarized into a single static route
floating static route
Floating static routes are static routes that are used to provide a backup path to a primary static or dynamic route, in the event of a link failure. The floating static route is only used when the primary route is not available.
A network administrator can manually configure a static route to reach a specific network. Unlike a dynamic routing protocol, static routes are not automatically updated and must be manually reconfigured any time the network topology changes.
administrative distance (AD)
is a measure of the preference of route sources. Route sources with low AD values are preferred over routes sources with higher AD values.
stub network
Routing to and from stub networks. A stubnetwork is a network accessed by a single route, and the router has only one neighbor.
default route
Using a single default route to represent a path to any network that does not have a more specific match with another route in the routing table. Default routes are used to send traffic to any destination beyond the next upstream router.
default static route ; 0.0.0.0/0
A default static route is simply a static route with 0.0.0.0/0 as the destination IPv4 address.
Gateway of Last Resort
A default route is used when no other routes in the routing table match the destination IP address of the packet. In other words, if a more specific match does not exist, then the default route is used as the Gateway of Last Resort.
more specific match
When no other routes in the routing table match the packet destination IP address. In other words, when a more specificmatch does not exist. A common use is when connecting a company's edge router to the ISP network.
summary static route
To reduce the number of routing table entries, multiple static routes can be summarized into a single static route
floating static route
Floating static routes are static routes that are used to provide a backup path to a primary static or dynamic route, in the event of a link failure. The floating static route is only used when the primary route is not available.
2018年11月13日 星期二
網路原理(一) RSE6 Section 1.3
Administrative Distance (AD)
Cisco IOS uses what is known as the administrative distance (AD) to determine the route to install into the IP routing table.
local route interfaces
Added when an interface is configured and active. This entry is only displayed in IOS 15 or newer for IPv4 routes and all IOS releases for IPv6 routes.
static routes
Added when a route is manually configured and the exit interface is active.
route timestamp
Identifies how much time has passed since the route was learned.
route source
Identifies how the route was learned.
以下為Cisco設備指令
ip route
ip route 0.0.0.0.0.0.0.0
ipv6 unicast-routing
ipv6 route
Router ?
ipv6 router ?
Cisco IOS uses what is known as the administrative distance (AD) to determine the route to install into the IP routing table.
local route interfaces
Added when an interface is configured and active. This entry is only displayed in IOS 15 or newer for IPv4 routes and all IOS releases for IPv6 routes.
static routes
Added when a route is manually configured and the exit interface is active.
route timestamp
Identifies how much time has passed since the route was learned.
route source
Identifies how the route was learned.
以下為Cisco設備指令
ip route
ip route 0.0.0.0.0.0.0.0
ipv6 unicast-routing
ipv6 route
Router ?
ipv6 router ?
網路原理(一) RSE6 Section 1.2
metrics
The best path is selected by a routing protocol based on the value or metric it uses to determine the distance to reach a network. A metric is the quantitative value used to measure the distance to a given network. The best path to a network is the path with the lowest metric.
routing information protocol (RIP)
路由信息協議是一種內部網關協議，為最早出現的距離向量路由協定。屬於網路層，其主要應用於規模較小的、可靠性要求較低的網絡，可以通過不斷的交換信息讓路由器動態的適應網絡連接的變化，這些信息包括每個路由器可以到達哪些網絡，這些網絡有多遠等。
open shortest path first (OSPF)
開放式最短路徑優先是對鏈路狀態路由協定的一種實現，隸屬內部網路關協定，故運作於自治系統內部。採用戴克斯特拉演算法被用來計算最短路徑樹。它使用「代價」作為路由度量。鏈路狀態資料庫用來儲存當前網路拓撲結構，路由器上屬於同一區域的鏈路狀態資料庫是相同的。
enhanced interior gateway routing protocol (EIGRP)
加強型閘道間選徑協定，又譯增強型企業網路關路由協定，一種企業網路關協定。在企業網路關路由協定的基礎上，由思科公司發展而成，於2013年Cisco將此標準公開，不再是私有的路由協定，在同樣。EIGRP是一種進階距離向量路由協定。
load balancing
負載平衡是一種電腦技術，用來在多個電腦、網路連接、CPU、磁碟驅動器或其他資源中分配負載，以達到最佳化資源使用、最大化吞吐率、最小化回應時間、同時避免過載的目的。 使用帶有負載平衡的多個伺服器元件，取代單一的元件，可以通過冗餘提高可靠性。負載平衡服務通常是由專用軟體和硬體來完成。
Intermediate system to intermediate system (ISIS)
中間系統到中間系統是一種企業網路關協定，是電信業者普遍採用的企業網路關協定之一。標準的IS-IS協定是由國際標準化組織制定的ISO/IEC 10589:2002 所規範的。
RIPng
RIP next generation
OSPFv3
OSPF第三版
The best path is selected by a routing protocol based on the value or metric it uses to determine the distance to reach a network. A metric is the quantitative value used to measure the distance to a given network. The best path to a network is the path with the lowest metric.
routing information protocol (RIP)
路由信息協議是一種內部網關協議，為最早出現的距離向量路由協定。屬於網路層，其主要應用於規模較小的、可靠性要求較低的網絡，可以通過不斷的交換信息讓路由器動態的適應網絡連接的變化，這些信息包括每個路由器可以到達哪些網絡，這些網絡有多遠等。
open shortest path first (OSPF)
開放式最短路徑優先是對鏈路狀態路由協定的一種實現，隸屬內部網路關協定，故運作於自治系統內部。採用戴克斯特拉演算法被用來計算最短路徑樹。它使用「代價」作為路由度量。鏈路狀態資料庫用來儲存當前網路拓撲結構，路由器上屬於同一區域的鏈路狀態資料庫是相同的。
enhanced interior gateway routing protocol (EIGRP)
加強型閘道間選徑協定，又譯增強型企業網路關路由協定，一種企業網路關協定。在企業網路關路由協定的基礎上，由思科公司發展而成，於2013年Cisco將此標準公開，不再是私有的路由協定，在同樣。EIGRP是一種進階距離向量路由協定。
load balancing
負載平衡是一種電腦技術，用來在多個電腦、網路連接、CPU、磁碟驅動器或其他資源中分配負載，以達到最佳化資源使用、最大化吞吐率、最小化回應時間、同時避免過載的目的。 使用帶有負載平衡的多個伺服器元件，取代單一的元件，可以通過冗餘提高可靠性。負載平衡服務通常是由專用軟體和硬體來完成。
Intermediate system to intermediate system (ISIS)
中間系統到中間系統是一種企業網路關協定，是電信業者普遍採用的企業網路關協定之一。標準的IS-IS協定是由國際標準化組織制定的ISO/IEC 10589:2002 所規範的。
RIPng
RIP next generation
OSPFv3
OSPF第三版
網路原理(一) RSE6 Section 1.1
topology
The physical topology is the arrangement of the cables, network devices, and end systems. It describes how the network devices are actually interconnected with wires and cables. The logical topology is the path over which the data is transferred in a network. It describes how the network devices appear connected to network users.
speed
Speed is a measure of the data rate in bits per second (b/s) of a given link in the network.
cost
Cost indicates the general expense for purchasing of network components, and installation and maintenance of the network.
security
Security indicates how protected the network is, including the information that is transmitted over the network.
availability
Availability is the likelihood that the network is available for use when it is required.
scalability
Scalability indicates how easily the network can accommodate more users and data transmission requirements.
reliability
Reliability indicates the dependability of the components that make up the network, such as the routers, switches, PCs, and servers.
point-to-point protocol
In computer networking, Point-to-Point Protocol (PPP) is a data link layer (layer 2) communications protocol used to establish a direct connection between two nodes. It connects two routers directly without any host or any other networking device in between.
process switching
An older packet forwarding mechanism still available for Cisco routers.
fast switching
This is a common packet forwarding mechanism which uses a fast-switching cache to store next-hop information.
cisco express forwarding (CEF)
CEF is the most recent and preferred Cisco IOS packet-forwarding mechanism. Like fast switching,
wireless access points (WAPs)
Laptops and smartphones connect wirelessly to wireless access points (WAPs).
edge router
The edge router connects to a WAN SP, and also connects to an ISP for backup purposes.
gateway of last resort
A router is also usually configured with its own default gateway. This is known as the Gateway of Last Resort.
topology diagram
拓樸圖
secure shell (SSH)
Secure Shell是一種加密的網路傳輸協定，可在不安全的網路中為網路服務提供安全的傳輸環境。
hypertext transfer protocol secure (HTTPS)
超文字傳輸安全協定（英語：Hypertext Transfer Protocol Secure，縮寫：HTTPS，常稱為HTTP over TLS，HTTP over SSL或HTTP Secure）是一種透過電腦網路進行安全通訊的傳輸協定。
console cable
console纜線
terminal emulation software - Tera Term, PuTTY, Hyper Terminal
PuTTY 、PieTTY 、Tera Term 都是知名的免費連線工具，單一程式免安裝就可以執行
臨時要 Telnet 、SSH 連線或是 terminal console 這些小程式都很方便
Secure management access
Secures privileged EXEC, user EXEC, and remote access.
loopback interface
The loopback interface is a logical interface internal to the router. It is not assigned to a physical port and can therefore never be connected to any other device. The loopback interface is useful in testing and managing a Cisco IOS device because it ensures that at least one interface will always be available. For example, it can be used for testing purposes, such as testing internal routing processes, by emulating networks behind the router.
以下為Cisco設備指令
no shutdown
interface loopback
show ip route
show running-config
show ip interface brief
show ip interfaces
show ipv6 interface
show interfaces
show ipv6 interface
show ipv6 route
Ctrl+P
Ctrl+N
show history
terminal history
The physical topology is the arrangement of the cables, network devices, and end systems. It describes how the network devices are actually interconnected with wires and cables. The logical topology is the path over which the data is transferred in a network. It describes how the network devices appear connected to network users.
speed
Speed is a measure of the data rate in bits per second (b/s) of a given link in the network.
cost
Cost indicates the general expense for purchasing of network components, and installation and maintenance of the network.
security
Security indicates how protected the network is, including the information that is transmitted over the network.
availability
Availability is the likelihood that the network is available for use when it is required.
scalability
Scalability indicates how easily the network can accommodate more users and data transmission requirements.
reliability
Reliability indicates the dependability of the components that make up the network, such as the routers, switches, PCs, and servers.
point-to-point protocol
In computer networking, Point-to-Point Protocol (PPP) is a data link layer (layer 2) communications protocol used to establish a direct connection between two nodes. It connects two routers directly without any host or any other networking device in between.
process switching
An older packet forwarding mechanism still available for Cisco routers.
fast switching
This is a common packet forwarding mechanism which uses a fast-switching cache to store next-hop information.
cisco express forwarding (CEF)
CEF is the most recent and preferred Cisco IOS packet-forwarding mechanism. Like fast switching,
wireless access points (WAPs)
Laptops and smartphones connect wirelessly to wireless access points (WAPs).
edge router
The edge router connects to a WAN SP, and also connects to an ISP for backup purposes.
gateway of last resort
A router is also usually configured with its own default gateway. This is known as the Gateway of Last Resort.
topology diagram
拓樸圖
secure shell (SSH)
Secure Shell是一種加密的網路傳輸協定，可在不安全的網路中為網路服務提供安全的傳輸環境。
hypertext transfer protocol secure (HTTPS)
超文字傳輸安全協定（英語：Hypertext Transfer Protocol Secure，縮寫：HTTPS，常稱為HTTP over TLS，HTTP over SSL或HTTP Secure）是一種透過電腦網路進行安全通訊的傳輸協定。
console cable
console纜線
terminal emulation software - Tera Term, PuTTY, Hyper Terminal
PuTTY 、PieTTY 、Tera Term 都是知名的免費連線工具，單一程式免安裝就可以執行
臨時要 Telnet 、SSH 連線或是 terminal console 這些小程式都很方便
Secure management access
Secures privileged EXEC, user EXEC, and remote access.
loopback interface
The loopback interface is a logical interface internal to the router. It is not assigned to a physical port and can therefore never be connected to any other device. The loopback interface is useful in testing and managing a Cisco IOS device because it ensures that at least one interface will always be available. For example, it can be used for testing purposes, such as testing internal routing processes, by emulating networks behind the router.
以下為Cisco設備指令
no shutdown
interface loopback
show ip route
show running-config
show ip interface brief
show ip interfaces
show ipv6 interface
show interfaces
show ipv6 interface
show ipv6 route
Ctrl+P
Ctrl+N
show history
terminal history
2018年11月8日 星期四
網路原理(一) Section 11
Application Filtering
Prevents or allows access by specific application types based on port numbers
Authentication, Authorization, and Accounting (AAA)
AAA is a way to control who is permitted to access a network (authenticate), what they can do while they are there (authorize), and what actions they perform while accessing the network (accounting).
auto secure (command)
exec timeout (command)
Exec timeouts can be configured on console, VTY, and aux ports using the exec-timeout command in line configuration mode.
crypto key generate rsa general-keys modulus modulus-size (command)
To generate the SSH key, use the crypto key generate rsa general-keys command in global configuration mode.
endpoint security
An endpoint, or host, is an individual computer system or device that acts as a network client.
ip domain-name domain-name (command)
Ensure that the router has a unique hostname, and then configure the IP domain name of the network using the ip domain-name command in global configuration mode.
login block-for 120 attempts 3 within 60 (command)
t is possible to prevent this type of attack by blocking login attempts to the device if a set number of failures occur within a specific amount of time.
Packet Filtering
Prevents or allows access based on IP or MAC addresses
passphrase
Therefore, one method to create a strong password is to use the space bar and create a phrase made of many words. This is called a passphrase.
Personal firewalls
Host-based firewalls or personal firewalls are installed on end systems.
security passwords min-length (command)
Additionally, to ensure that all configured passwords are a minimum of a specified length, use the security passwords min-length command in global configuration mode.
Stateful Packet Inspection (SPI)
Incoming packets must be legitimate responses to requests from internal hosts.
transport input ssh
Enable inbound SSH sessions using the line vty commands login local and transport input ssh.
URL Filtering
Prevents or allows access to websites based on specific URLs or keywords
! . U
Address Resolution Protocol (ARP)
位址解析協定(ARP) 是通過解析網路層位址來找尋資料鏈路層位址的一個在網路協定包中極其重要的網路傳輸協定。
ipconfig (host command)
查看介面卡配置
loopback address
127.0.0.1
ping (command)
ping是一種電腦網路工具，用來測試封包能否透過IP協定到達特定主機。
service password-encryption (command)
密碼加密
show cdp neighbors (IOS command)
The show cdp neighbors detail command reveals the IP address of a neighboring device.
show ip interface brief (IOS command)
The show ip interface brief output displays all interfaces on the router, the IP address assigned to each interface, if any, and the operational status of the interface.
tracert (host command) ; traceroute (IOS command)
traceroute，現代Linux系統稱為tracepath，Windows系統稱為tracert，是一種電腦網路工具。它可顯示封包在IP網路經過的路由器的IP位址。
網路原理(一) Section 10.2
IMAP
網際網路資訊存取協定（縮寫為IMAP，以前稱作互動郵件存取協定）是一個應用層協定，用來從本地郵件用戶端（如Microsoft Outlook、Outlook Express、Foxmail、Mozilla Thunderbird）存取遠端伺服器上的郵件。
Port 25 (SMTP)
25Port分配給SMTP（簡單郵件傳輸協定）
TCP port 110 (POP)
110Port是為POP3（郵件協定3）服務開放的
Domain name
在說明 DNS Server 前，可能要先說明什麼叫 Domain Name，在網路上辨別一台電腦的方式是利用 IP，但是一組 IP 數字很不容易記，且沒有什麼聯想的意義，因此，我們會為網路上的伺服器取一個有意義又容易記的名字，這個名字我們就叫它「Domain Name」。
DNS Protocol
The Domain Network System (DNS) protocol helps Internet users and network devices discover websites using human-readable hostnames, instead of numeric IP addresses.
Record types: A, NS, AAAA, MX
The DNS server stores different types of resource records used to resolve names. These records contain the name, address, and type of record.
ipconffig /displaydns
指令
Top-level domains are: .com, .org, .au, .co
The different top-level domains represent either the type of organization or the country of origin.
nslookup
DNS偵錯工具
Dynamic Host Configuration Protocol (DHCP) for IPv4
The Dynamic Host Configuration Protocol (DHCP) for IPv4 service automates the assignment of IPv4 addresses, subnet masks, gateways, and other IPv4 networking parameters.
DHCPv6
DHCPv6 (DHCP for IPv6) provides similar services for IPv6 clients.
DHCP Discover
As shown in the figure, when an IPv4, DHCP-configured device boots up or connects to the network, the client broadcasts a DHCP discover (DHCPDISCOVER) message to identify any available DHCP servers on the network.
DHCP Offer
The client may receive multiple DHCPOFFER messages if there is more than one DHCP server on the local network.
DHCP Request
Therefore, it must choose between them, and sends a DHCP request (DHCPREQUEST) message that identifies the explicit server and lease offer that the client is accepting.
DHCP Acknowledgement
Assuming that the IPv4 address requested by the client, or offered by the server, is still available, the server returns a DHCP acknowledgment (DHCPACK) message that acknowledges to the client that the lease has been finalized.
DHCP Negative Acknowledgement
If the offer is no longer valid, then the selected server responds with a DHCP negative acknowledgment (DHCPNAK) message.
DHCPv6: SOLICIT, ADVERTISE, INFORMATION, REQUEST, and REPLY
The DHCPv6 messages
FTP daemon (FTPd)
FTP server
Server Message Block (SMB)
伺服器訊息區塊，又稱網路檔案分享系統，一種應用層網路傳輸協定，由微軟開發，主要功能是使網路上的機器能夠共享電腦檔案、印表機、串列埠和通訊等資源。
網際網路資訊存取協定（縮寫為IMAP，以前稱作互動郵件存取協定）是一個應用層協定，用來從本地郵件用戶端（如Microsoft Outlook、Outlook Express、Foxmail、Mozilla Thunderbird）存取遠端伺服器上的郵件。
Port 25 (SMTP)
25Port分配給SMTP（簡單郵件傳輸協定）
TCP port 110 (POP)
110Port是為POP3（郵件協定3）服務開放的
Domain name
在說明 DNS Server 前，可能要先說明什麼叫 Domain Name，在網路上辨別一台電腦的方式是利用 IP，但是一組 IP 數字很不容易記，且沒有什麼聯想的意義，因此，我們會為網路上的伺服器取一個有意義又容易記的名字，這個名字我們就叫它「Domain Name」。
DNS Protocol
The Domain Network System (DNS) protocol helps Internet users and network devices discover websites using human-readable hostnames, instead of numeric IP addresses.
Record types: A, NS, AAAA, MX
The DNS server stores different types of resource records used to resolve names. These records contain the name, address, and type of record.
ipconffig /displaydns
指令
Top-level domains are: .com, .org, .au, .co
The different top-level domains represent either the type of organization or the country of origin.
nslookup
DNS偵錯工具
Dynamic Host Configuration Protocol (DHCP) for IPv4
The Dynamic Host Configuration Protocol (DHCP) for IPv4 service automates the assignment of IPv4 addresses, subnet masks, gateways, and other IPv4 networking parameters.
DHCPv6
DHCPv6 (DHCP for IPv6) provides similar services for IPv6 clients.
DHCP Discover
As shown in the figure, when an IPv4, DHCP-configured device boots up or connects to the network, the client broadcasts a DHCP discover (DHCPDISCOVER) message to identify any available DHCP servers on the network.
DHCP Offer
The client may receive multiple DHCPOFFER messages if there is more than one DHCP server on the local network.
DHCP Request
Therefore, it must choose between them, and sends a DHCP request (DHCPREQUEST) message that identifies the explicit server and lease offer that the client is accepting.
DHCP Acknowledgement
Assuming that the IPv4 address requested by the client, or offered by the server, is still available, the server returns a DHCP acknowledgment (DHCPACK) message that acknowledges to the client that the lease has been finalized.
DHCP Negative Acknowledgement
If the offer is no longer valid, then the selected server responds with a DHCP negative acknowledgment (DHCPNAK) message.
DHCPv6: SOLICIT, ADVERTISE, INFORMATION, REQUEST, and REPLY
The DHCPv6 messages
FTP daemon (FTPd)
FTP server
Server Message Block (SMB)
伺服器訊息區塊，又稱網路檔案分享系統，一種應用層網路傳輸協定，由微軟開發，主要功能是使網路上的機器能夠共享電腦檔案、印表機、串列埠和通訊等資源。
網路原理(一) Section 10.1
Hypertext transfer protocol (HTTP)
超文本傳輸協定（英文：HyperText Transfer Protocol，縮寫：HTTP）是一種用於分佈式、協作式和超媒體信息系統的應用層協議。
File Transfer Protocol (FTP)
檔案傳輸協定是用於在網路上進行檔案傳輸的一套標準協定，使用客戶/伺服器模式。
Trivial File Transfer Protocol (TFTP)
簡單檔案傳輸協定也稱小型檔案傳輸協定（Trivial File Transfer Protocol, TFTP），是一種於1981年在RFC 783中定義的簡化的檔案傳輸協定（FTP）。
Internet Message Access Protocol (IMAP)
網際網路資訊存取協定（縮寫為IMAP，以前稱作互動郵件存取協定）是一個應用層協定，用來從本地郵件用戶端（如Microsoft Outlook、Outlook Express、Foxmail、Mozilla Thunderbird）存取遠端伺服器上的郵件。
Domain Name System (DNS)
網域名稱系統（英文：Domain Name System，縮寫：DNS）是網際網路的一項服務。
Simple Mail Transport Protocol (SMTP)
簡單郵件傳輸協定(Simple Mail Transfer Protocol, SMTP) 是在Internet傳輸email的事實標準。
Post Office Protocol (POP)
Email protocol
Dynamic Host Configuration Protocol (DHCP)
動態主機設定協定（英語：Dynamic Host Configuration Protocol，DHCP）是一個區域網路的網路協定，使用UDP協定工作，主要有兩個用途： 用於內部網路或網路服務供應商自動分配IP位址給用戶
Quick Time and Motion Picture Experts Group (MPEG)
Some well-known standards for video include QuickTime and Motion Picture Experts Group (MPEG).
Graphics Interchange Format (GIF)
圖像互換格式是一種點陣圖圖形檔案格式，以8位元色重現真彩色的圖像。
Joint Photographic Experts Group (JPEG)
在電腦中，JPEG是一種針對相片影像而廣泛使用的失真壓縮標準方法。
Portable Network Graphics (PNG)
可攜式網路圖形是一種無失真壓縮的點陣圖圖形格式，支援索引、灰度、RGB三種顏色方案以及Alpha通道等特性。
BOOTP
BOOTP是一種網路協定，讓電腦或其他周邊儀器可以從伺服器下載啟動程式。
HTTPS
超文字傳輸安全協定（英語：Hypertext Transfer Protocol Secure，縮寫：HTTPS，常稱為HTTP over TLS，HTTP over SSL或HTTP Secure）是一種透過電腦網路進行安全通訊的傳輸協定。
Client-server model
主從式架構(英語：Client–server model) 也稱用戶端-伺服器（Client/Server）架構、C/S架構，是一種網路架構，它把用戶端 (Client) （通常是一個採用圖形化使用者介面的程式）與伺服器(Server) 區分開來。
Peer-to-peer network (P2P)
In its simplest form, a peer-to-peer (P2P) network is created when two or more PCs are connected and share resources without going through a separate server computer.
P2P applications
A P2P application allows a device to act as both a client and a server within the same communication.
Gnutella protocol
Some P2P applications are based on the Gnutella protocol, where each user shares whole files with other users.
BitTorrent
BitTorrent協定是用在對等網路中檔案分享的網路協定程式。
Uniform Resource Locator (URL)
URL（全名Uniform Resource Locator），又譯劃一資源定位器，俗稱網頁地址（網址）
Uniform Resource Identifier (URLs)
URI可被視為定位符（URL），名稱（URN）或兩者兼備。
Get
A client request for data. A client (web browser) sends the GET message to the web server to request HTML pages.
Post
Uploads data files to the web server such as form data.
Put
Uploads resources or content to the web server such as an image.
HTTP Secure (HTTPS)
HTTPS uses authentication and encryption to secure data as it travels between the client and server.
Secure Socket Layer (SSL)
HTTPS uses the same client request-server response process as HTTP, but the data stream is encrypted with Secure Socket Layer (SSL) before being transported across the network.
超文本傳輸協定（英文：HyperText Transfer Protocol，縮寫：HTTP）是一種用於分佈式、協作式和超媒體信息系統的應用層協議。
File Transfer Protocol (FTP)
檔案傳輸協定是用於在網路上進行檔案傳輸的一套標準協定，使用客戶/伺服器模式。
Trivial File Transfer Protocol (TFTP)
簡單檔案傳輸協定也稱小型檔案傳輸協定（Trivial File Transfer Protocol, TFTP），是一種於1981年在RFC 783中定義的簡化的檔案傳輸協定（FTP）。
Internet Message Access Protocol (IMAP)
網際網路資訊存取協定（縮寫為IMAP，以前稱作互動郵件存取協定）是一個應用層協定，用來從本地郵件用戶端（如Microsoft Outlook、Outlook Express、Foxmail、Mozilla Thunderbird）存取遠端伺服器上的郵件。
Domain Name System (DNS)
網域名稱系統（英文：Domain Name System，縮寫：DNS）是網際網路的一項服務。
Simple Mail Transport Protocol (SMTP)
簡單郵件傳輸協定(Simple Mail Transfer Protocol, SMTP) 是在Internet傳輸email的事實標準。
Post Office Protocol (POP)
Email protocol
Dynamic Host Configuration Protocol (DHCP)
動態主機設定協定（英語：Dynamic Host Configuration Protocol，DHCP）是一個區域網路的網路協定，使用UDP協定工作，主要有兩個用途： 用於內部網路或網路服務供應商自動分配IP位址給用戶
Quick Time and Motion Picture Experts Group (MPEG)
Some well-known standards for video include QuickTime and Motion Picture Experts Group (MPEG).
Graphics Interchange Format (GIF)
圖像互換格式是一種點陣圖圖形檔案格式，以8位元色重現真彩色的圖像。
Joint Photographic Experts Group (JPEG)
在電腦中，JPEG是一種針對相片影像而廣泛使用的失真壓縮標準方法。
Portable Network Graphics (PNG)
可攜式網路圖形是一種無失真壓縮的點陣圖圖形格式，支援索引、灰度、RGB三種顏色方案以及Alpha通道等特性。
BOOTP
BOOTP是一種網路協定，讓電腦或其他周邊儀器可以從伺服器下載啟動程式。
HTTPS
超文字傳輸安全協定（英語：Hypertext Transfer Protocol Secure，縮寫：HTTPS，常稱為HTTP over TLS，HTTP over SSL或HTTP Secure）是一種透過電腦網路進行安全通訊的傳輸協定。
Client-server model
主從式架構(英語：Client–server model) 也稱用戶端-伺服器（Client/Server）架構、C/S架構，是一種網路架構，它把用戶端 (Client) （通常是一個採用圖形化使用者介面的程式）與伺服器(Server) 區分開來。
Peer-to-peer network (P2P)
In its simplest form, a peer-to-peer (P2P) network is created when two or more PCs are connected and share resources without going through a separate server computer.
P2P applications
A P2P application allows a device to act as both a client and a server within the same communication.
Gnutella protocol
Some P2P applications are based on the Gnutella protocol, where each user shares whole files with other users.
BitTorrent
BitTorrent協定是用在對等網路中檔案分享的網路協定程式。
Uniform Resource Locator (URL)
URL（全名Uniform Resource Locator），又譯劃一資源定位器，俗稱網頁地址（網址）
Uniform Resource Identifier (URLs)
URI可被視為定位符（URL），名稱（URN）或兩者兼備。
Get
A client request for data. A client (web browser) sends the GET message to the web server to request HTML pages.
Post
Uploads data files to the web server such as form data.
Put
Uploads resources or content to the web server such as an image.
HTTP Secure (HTTPS)
HTTPS uses authentication and encryption to secure data as it travels between the client and server.
Secure Socket Layer (SSL)
HTTPS uses the same client request-server response process as HTTP, but the data stream is encrypted with Secure Socket Layer (SSL) before being transported across the network.
網路原理(一) Section 9
Segmentation
切割
Multiplexing
Sending some types of data (for example, a streaming video) across a network, as one complete communication stream, can consume all of the available bandwidth.
Transmission Control Protocol (TCP)
傳輸控制協定（英語：Transmission Control Protocol，縮寫為TCP）是一種連接導向的、可靠的、基於位元組流的傳輸層通訊協定，由IETF的RFC 793定義。
Flow Control
Network hosts have limited resources, such as memory and processing power.
User Datagram Protocol (UDP)
用戶資料報協定（英語：User Datagram Protocol，縮寫為UDP），又稱使用者資料包協定，是一個簡單的面向資料報的傳輸層協定，正式規範為RFC 768。
Port Addressing
By default, Port Addressing is disabled, which means that the physical emulation ports operate like a network switch (or bridge).
Socket
Sockets enable multiple processes, running on a client, to distinguish themselves from each other, and multiple connections to a server process to be distinguished from each other.
Three-way Handshake
To establish the connection, the hosts perform a three-way handshake.
Initial Sequence Number (ISN)
This ISN represents the starting value of the bytes for this session that is transmitted to the receiving application.
Sequence Numbers
This ISN represents the starting value of the bytes for this session that is transmitted to the receiving application.
Window Size
Indicates the number of bytes that can be accepted at one time.
Flow Control-Congestion Avoidance
When congestion occurs on a network, it results in packets being discarded by the overloaded router.
切割
Multiplexing
Sending some types of data (for example, a streaming video) across a network, as one complete communication stream, can consume all of the available bandwidth.
Transmission Control Protocol (TCP)
傳輸控制協定（英語：Transmission Control Protocol，縮寫為TCP）是一種連接導向的、可靠的、基於位元組流的傳輸層通訊協定，由IETF的RFC 793定義。
Flow Control
Network hosts have limited resources, such as memory and processing power.
User Datagram Protocol (UDP)
用戶資料報協定（英語：User Datagram Protocol，縮寫為UDP），又稱使用者資料包協定，是一個簡單的面向資料報的傳輸層協定，正式規範為RFC 768。
Port Addressing
By default, Port Addressing is disabled, which means that the physical emulation ports operate like a network switch (or bridge).
Socket
Sockets enable multiple processes, running on a client, to distinguish themselves from each other, and multiple connections to a server process to be distinguished from each other.
Three-way Handshake
To establish the connection, the hosts perform a three-way handshake.
Initial Sequence Number (ISN)
This ISN represents the starting value of the bytes for this session that is transmitted to the receiving application.
Sequence Numbers
This ISN represents the starting value of the bytes for this session that is transmitted to the receiving application.
Window Size
Indicates the number of bytes that can be accepted at one time.
Flow Control-Congestion Avoidance
When congestion occurs on a network, it results in packets being discarded by the overloaded router.
2018年11月5日 星期一
網路原理(一) Section 8.1
Subnetting
The solution is to reduce the size of the network to create smaller broadcast domains in a process called subnetting.
Classful Boundary
分類的邊界
Classless Subnetting
The examples seen so far borrowed host bits from the common /8, /16, and /24 network prefixes. However, subnets can borrow bits from any host bit position to create other masks.
Magic number
讓人模糊的數字
Variable Length Subnet Mask (VLSM)
In all of the previous examples of subnetting, notice that the same subnet mask was applied for all the subnets.
Global Routing Prefix
The IPv6 global unicast address normally consists of a /48 global routingprefix, a 16 bit subnet ID, and a 64 bit interface ID.
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