ip default-network 0.0.0.0
ip route 0.0.0.0 0.0.0.0 172.16.2.1
cdp run
traceroute
debug ip icmp
最优路由的衡量标准
show version可以查看设备最后一次是用哪种方式重启的
WAN链路的封装方法：PPP HDLC(highlevel data link control) ATM(asynchronous transfer mode)
LMI(local management interface)是Frame Relay(帧中继)的一个概念
CIR(committed information rate)
帧中继点对点子接口的特征：每个子接口需要一个独立的网段，类似专线
show access-list
SSID(service set id) names and identifies a wireless network
基于RC4的无线加密算法：WEP TKIP
RIPv2的特征：变长的子网掩码 手动路由汇总
支持传输距离超过550米的以太网光纤模块:1000BASE-LX 1000BASE-ZX
terminal monitor
arp(address resolution protocol)表，是IP地址和MAC地址之间的映射 。
PAT(port address translation)把内部网络映射到外部网络IP地址的不同端口上，实现一对多对于节省IP地址是最为有效的。是NAT的特殊形式，
NAT(network address translation)是为了解决公网IP地址有限的问题。
包括PAT,Pooled NAT,Static NAT
inside local - 内部网络地址
inside global - 内部网络映射的外网地址
outside local - this is the local IP address from the private network, which your local host sees as the IP address of the remote host
outside global - this is the public IP address of the remote host (e.g., the IP address of the remote web server that a workstation is connecting to)
ip nat pool mypool 63.63.64.2 63.63.63.2 prefix 30
access-list 1 permit 10.10.0.0 0.0.0.255
ip nat inside source list 1 pool mypool overload
interface ethernet 0
ip nat inside
interface serial 0
ip nat outside
预留IP地址范围
10.0.0.0/8-10.255.255.255/8
172.16.0.0/16-172.31.255.255/16
192.168.0.0/24-192.168.255.255/24
代理ARP
当主机将自己COM口连设备的CONSOLE口时要用全反线
网桥和交换机
1. 都转发2层广播
2. 交换机比网桥有更多端口
3. 都工作在2层
link-state protocol链路状态路由协议
1. provides common view of entire topology: show ip ospf database
2. calculates shortest path
3. utilizes event-triggered updates
冲突域和广播域
路由器一个端口一个广播域，交换机一个端口一个冲突域，集线器一个冲突域
VLAN trunk的交换机端口模式：auto on desirable
OSPF路由协议的特征：
区域ID设置为0-65535
区域0是骨干区域
多区域情况必须存在0区域
链路状态协议如何维护拓扑数据库？
hello package, 来自其他路由器的LSA(link state advertisement)
OSPF路由协议：支持VLSM(variable length subnet mask可变长子网掩碼), 把网络不稳定性限制在一定范围内, 允许路由更新控制
实现设备的远程管理，首先要给交换机配置管理IP，其次是要路由可达。2层交换机只能在VLAN中配置IP。
vtp server
vlan50
流控(flow control)的措施：buffer(缓存), windowing(窗口机制), congestion avoidance(拥塞控制)
ip subnet-zero
STP选举原则
OSPF路由协议的特征：收敛(converge)快, 使用cost值确定最优路由, 在交换路由信息前先建立邻里关系
最优路由的比较：先比较AD值，然后再比较metric值
EIGRP 90 OSPF 110 RIP 120
show controller S0/0
PPP (layer 2 protocol encapsulation type) supports synchronous and asynchronous circuits and has built-in security mechanisms.
which command can be used to verify the DLCI destination address in a Frame Relay static configuration?
show frame-relay map
选举根桥(root bridge)
如果优先级相同的情况，MAC地址最小的为根桥
OSPF route-id的选举
1. 如果有本地loopback地址，则选loopback地址最大的；
2. 选取最大的以太网口IP地址；
vlan号1006-4094属于扩展vlan，只能在透明模式配置
which PPP subprotocol negotiates authentication options?
LCP (link control protocol)
which two data link layers are supported by cisco iso software for IPv6?
FDDI, Frame Relay PVC
FCS(Frame Check Sequence) is a field at the end of the frame that's used to store the CRC.
OSPF使用带宽计算cost, EIGRP以带宽，延时，负载，可靠性和MTU来度量，IS-IS以默认，延迟，开销，差错来度量
ppp authentication chap pap
show file systems
enhances the 802.1d convergence time on ports that are connected to hosts:
spanning-tree portfast
determine a cisco router chassis serial number:
show inventory
show diag
l
enable IPv6 forwarding on a cisco router:
ipv6 unicast-routing
tunnel隧道
IPv6胜过IPv4的两个地方：no broadcast, auto-configuration
IPSec ESP(Encapsulating Security Payload)
TTL(time to live)
is the IPv6 all-RIP-routers multicast group address that is used by RIPng as the destaion address
FF02::9
Cisco支持Frame-Relay封装格式：cisco, IETF
EIGRP converges fast RIP because of DUAL and backup routes that are stored in the topology table;
EIGRP uses a hello protocol to establish neighbor relationships;
EIGRP supports VLSM and authentication for routing updates;
Teredo
VTP advertisements delivered to switches across the network:
multicast frames
used in troubleshooting, can enabledebug output to a remote location:
terminal monitor
logging host ip-address
HMAC-MD5 HMAC-SHA-1
source address and wildcard mask are standard access list based.
show ip ospf database
show interfaces f0/24 switchport
show interfaces trunk
starndard access list(1-99) is based on source address and wildcard mask.
水平分割(split horizon):路由器从某个接口收到的更新信息不允许再从这个接口发送出去。
information about a route should not be sent back in the direction from which the original update came.
on point-to-point networks, OSPF hello packets are addressed to 224.0.0.5
show cdp neighbors detail
CIR(committed information rate)
以太网端口的三种链路类型：access，hybrid和trunk；
access类型的端口只属于一个VLAN；
trunk类型的端口允许多个VLAN通过；
frame relay point-to-point subinterface的两个特征：
1. they require a unique subnet within a routing domain;
2. they emulate leased lines;
WPAv1 add two features to address the inherent weaknesses found in WEP:
1. key mixing using temporal keys;
2. per frame sequence counters;
which two wireless encryption methods are based on the RC4 encryption algorithm: WEP, TKIP
距离矢量路由协议做的两件事：
1. send periodic updates regardless of topology changes;
2. update the routing table based on updates from their neighbors;
链路状态协议的3个特征：
1. 提供整个拓扑结构的整体视图；
2. 计算最短路径；
3. 利用基于事件的更新。
集线器只有一个冲突域，交换机每个端口都是一个冲突域。
使用VLAN trunk的交换机口的模式auto, on, desirable.
STP的选举原则 RID=优先级+mac地址 小者优先
OSPF配置默认路由 default-information originate
802.11a: 54Mbps
802.11b: 11Mbps
802.11g: 54 108Mbps
802.11n: 300Mbps
RIPv2 default update period is 30 seconds.
只有半双工模式才存在冲突。
RIP如果路由失效，holdtime之内都会表示possible down，经过60s刷新事件才会从路由表删除。刷新频率为30s。
PPP在进行认证配置时，用户名师对端的用户名，但是password要是两边共享的。
配置vty的access list时用命令access-class!!!!
2层交换机优于集线器的地方：
1. filtering frames basedon MAC addresses;
2. allowing simultaneous frame transmissions.
2层交换机是一个全双工设备，而hub是一个半双工设备，所以hub只有一个冲突域，而2层交换机的每个端口都是一个冲突域。另外2层交换机会MAC地址学习，所以它能基于MAC地址进行过滤帧，而HUB只是傻瓜式转发。
STP(802.1d)的端口状态disabled learning blocking listening forwarding，RSTP将前3中状态合并成一个状态discarding。
802.11b的最高速率为11Mbps，802.11g的最高速率为54Mbps。更具实际情况也可以采用5.5Mbps，2Mbps，1Mbps。
ip route 0.0.0.0 0.0.0.0 172.16.2.1
cdp run
traceroute
debug ip icmp
最优路由的衡量标准
show version可以查看设备最后一次是用哪种方式重启的
WAN链路的封装方法：PPP HDLC(highlevel data link control) ATM(asynchronous transfer mode)
LMI(local management interface)是Frame Relay(帧中继)的一个概念
CIR(committed information rate)
帧中继点对点子接口的特征：每个子接口需要一个独立的网段，类似专线
show access-list
SSID(service set id) names and identifies a wireless network
基于RC4的无线加密算法：WEP TKIP
RIPv2的特征：变长的子网掩码 手动路由汇总
支持传输距离超过550米的以太网光纤模块:1000BASE-LX 1000BASE-ZX
terminal monitor
arp(address resolution protocol)表，是IP地址和MAC地址之间的映射 。
PAT(port address translation)把内部网络映射到外部网络IP地址的不同端口上，实现一对多对于节省IP地址是最为有效的。是NAT的特殊形式，
NAT(network address translation)是为了解决公网IP地址有限的问题。
包括PAT,Pooled NAT,Static NAT
inside local - 内部网络地址
inside global - 内部网络映射的外网地址
outside local - this is the local IP address from the private network, which your local host sees as the IP address of the remote host
outside global - this is the public IP address of the remote host (e.g., the IP address of the remote web server that a workstation is connecting to)
ip nat pool mypool 63.63.64.2 63.63.63.2 prefix 30
access-list 1 permit 10.10.0.0 0.0.0.255
ip nat inside source list 1 pool mypool overload
interface ethernet 0
ip nat inside
interface serial 0
ip nat outside
预留IP地址范围
10.0.0.0/8-10.255.255.255/8
172.16.0.0/16-172.31.255.255/16
192.168.0.0/24-192.168.255.255/24
代理ARP
当主机将自己COM口连设备的CONSOLE口时要用全反线
网桥和交换机
1. 都转发2层广播
2. 交换机比网桥有更多端口
3. 都工作在2层
link-state protocol链路状态路由协议
1. provides common view of entire topology: show ip ospf database
2. calculates shortest path
3. utilizes event-triggered updates
冲突域和广播域
路由器一个端口一个广播域，交换机一个端口一个冲突域，集线器一个冲突域
VLAN trunk的交换机端口模式：auto on desirable
OSPF路由协议的特征：
区域ID设置为0-65535
区域0是骨干区域
多区域情况必须存在0区域
链路状态协议如何维护拓扑数据库？
hello package, 来自其他路由器的LSA(link state advertisement)
OSPF路由协议：支持VLSM(variable length subnet mask可变长子网掩碼), 把网络不稳定性限制在一定范围内, 允许路由更新控制
实现设备的远程管理，首先要给交换机配置管理IP，其次是要路由可达。2层交换机只能在VLAN中配置IP。
vtp server
vlan50
流控(flow control)的措施：buffer(缓存), windowing(窗口机制), congestion avoidance(拥塞控制)
ip subnet-zero
STP选举原则
OSPF路由协议的特征：收敛(converge)快, 使用cost值确定最优路由, 在交换路由信息前先建立邻里关系
最优路由的比较：先比较AD值，然后再比较metric值
EIGRP 90 OSPF 110 RIP 120
show controller S0/0
PPP (layer 2 protocol encapsulation type) supports synchronous and asynchronous circuits and has built-in security mechanisms.
which command can be used to verify the DLCI destination address in a Frame Relay static configuration?
show frame-relay map
选举根桥(root bridge)
如果优先级相同的情况，MAC地址最小的为根桥
OSPF route-id的选举
1. 如果有本地loopback地址，则选loopback地址最大的；
2. 选取最大的以太网口IP地址；
vlan号1006-4094属于扩展vlan，只能在透明模式配置
which PPP subprotocol negotiates authentication options?
LCP (link control protocol)
which two data link layers are supported by cisco iso software for IPv6?
FDDI, Frame Relay PVC
FCS(Frame Check Sequence) is a field at the end of the frame that's used to store the CRC.
OSPF使用带宽计算cost, EIGRP以带宽，延时，负载，可靠性和MTU来度量，IS-IS以默认，延迟，开销，差错来度量
ppp authentication chap pap
show file systems
enhances the 802.1d convergence time on ports that are connected to hosts:
spanning-tree portfast
determine a cisco router chassis serial number:
show inventory
show diag
l
enable IPv6 forwarding on a cisco router:
ipv6 unicast-routing
tunnel隧道
IPv6胜过IPv4的两个地方：no broadcast, auto-configuration
IPSec ESP(Encapsulating Security Payload)
TTL(time to live)
is the IPv6 all-RIP-routers multicast group address that is used by RIPng as the destaion address
FF02::9
Cisco支持Frame-Relay封装格式：cisco, IETF
EIGRP converges fast RIP because of DUAL and backup routes that are stored in the topology table;
EIGRP uses a hello protocol to establish neighbor relationships;
EIGRP supports VLSM and authentication for routing updates;
Teredo
VTP advertisements delivered to switches across the network:
multicast frames
used in troubleshooting, can enabledebug output to a remote location:
terminal monitor
logging host ip-address
HMAC-MD5 HMAC-SHA-1
source address and wildcard mask are standard access list based.
show ip ospf database
show interfaces f0/24 switchport
show interfaces trunk
starndard access list(1-99) is based on source address and wildcard mask.
水平分割(split horizon):路由器从某个接口收到的更新信息不允许再从这个接口发送出去。
information about a route should not be sent back in the direction from which the original update came.
on point-to-point networks, OSPF hello packets are addressed to 224.0.0.5
show cdp neighbors detail
CIR(committed information rate)
以太网端口的三种链路类型：access，hybrid和trunk；
access类型的端口只属于一个VLAN；
trunk类型的端口允许多个VLAN通过；
frame relay point-to-point subinterface的两个特征：
1. they require a unique subnet within a routing domain;
2. they emulate leased lines;
WPAv1 add two features to address the inherent weaknesses found in WEP:
1. key mixing using temporal keys;
2. per frame sequence counters;
which two wireless encryption methods are based on the RC4 encryption algorithm: WEP, TKIP
距离矢量路由协议做的两件事：
1. send periodic updates regardless of topology changes;
2. update the routing table based on updates from their neighbors;
链路状态协议的3个特征：
1. 提供整个拓扑结构的整体视图；
2. 计算最短路径；
3. 利用基于事件的更新。
集线器只有一个冲突域，交换机每个端口都是一个冲突域。
使用VLAN trunk的交换机口的模式auto, on, desirable.
STP的选举原则 RID=优先级+mac地址 小者优先
OSPF配置默认路由 default-information originate
802.11a: 54Mbps
802.11b: 11Mbps
802.11g: 54 108Mbps
802.11n: 300Mbps
RIPv2 default update period is 30 seconds.
只有半双工模式才存在冲突。
RIP如果路由失效，holdtime之内都会表示possible down，经过60s刷新事件才会从路由表删除。刷新频率为30s。
PPP在进行认证配置时，用户名师对端的用户名，但是password要是两边共享的。
配置vty的access list时用命令access-class!!!!
2层交换机优于集线器的地方：
1. filtering frames basedon MAC addresses;
2. allowing simultaneous frame transmissions.
2层交换机是一个全双工设备，而hub是一个半双工设备，所以hub只有一个冲突域，而2层交换机的每个端口都是一个冲突域。另外2层交换机会MAC地址学习，所以它能基于MAC地址进行过滤帧，而HUB只是傻瓜式转发。
STP(802.1d)的端口状态disabled learning blocking listening forwarding，RSTP将前3中状态合并成一个状态discarding。
802.11b的最高速率为11Mbps，802.11g的最高速率为54Mbps。更具实际情况也可以采用5.5Mbps，2Mbps，1Mbps。
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