数据链路层移动性技术 苏锐丹
数据链路层移动性技术 苏锐丹
■P地址是分配给主机的网络接口 ▣一个主机可能有多个网络接口 Internet socket ■IP Address,Port ■P地址与接口相关 Solving mobility below IP layer is attractive IP Point of Attachment remain static Mobility is hidden from Correspondent Node Data Link layer domain cover area ▣Big or small area
◼ IP地址是分配给主机的网络接口 一个主机可能有多个网络接口 Internet socket ◼ IP Address，Port ◼ IP地址与接口相关 ◼ Solving mobility below IP layer is attractive IP Point of Attachment remain static Mobility is hidden from Correspondent Node ◼ Data Link layer domain cover area Big or small area
■Local Mobility ▣交换式以太网 ▣WLAN ■Vide Area mobility ▣3G/4G ▣ViMax
◼ Local Mobility 交换式以太网 WLAN ◼ Wide Area mobility 3G/4G WiMax
Mobility Across an Ethernet- Bridged Domain ■ “心脏”：介质访问控制(MAC)地址表也 叫内容可寻址存储器(CAM) 动态学习 ▣学习过程 口超时 静态配置 ▣减轻广播的流量 口仅允许特定的设备访问网络 CAM大小是有限的
Mobility Across an EthernetBridged Domain ◼ “心脏”：介质访问控制（MAC）地址表也 叫内容可寻址存储器（CAM） ◼ 动态学习 学习过程 超时 ◼ 静态配置 减轻广播的流量 仅允许特定的设备访问网络 ◼ CAM大小是有限的
MAC Address Table Port Addresses that can be reached D 0260.60AA.AAAA 0260.60DD.DDDD B 0260.60BB.BBBB 0260.60CC.CCCC
MAC Address Table Port Addresses that can be reached 0260.60AA.AAAA 2 0260.60BB.BBBB 3 0260.60CC.CCCC 4 2060.60DD.DDDD A D 0260.60AA.AAAA 0260.60DD.DDDD 0260.60BB.BBBB 0260.60CC.CCCC
■ Learning:When the bridge receives an Ethernet frame from a device,it records the source MAC address and the source interface. ■ Flooding:When a bridge receives an Ethernet frame with an unknown destination MAC address,it floods the frame by forwarding it to all forwarding interfaces except for the one on which it received the frame. Filtering:When the bridge receives an Ethernet frame with a destination MAC address on an interface that it has previously recorded the address as a source MAC address,the bridge will filter the frame by discarding it. Forwarding:When the bridge receives an Ethernet frame with a destination MAC address that it has previously recorded and the associated interface is different from the one on which the frame was received,the bridge forwards the frame out of the recorded interface. Aging:When the bridge records a source MAC address and associated interface,it will timestamp the record.If the bridge doesn't see another frame from the source MAC address before an aging timer expires,the record is deleted
■H2的P地址是静态分派的 B1 Interface #1 Interface H2 #2 Move B2 H2 Note The default timer for aging out MAC entries in Cisco switches is 5 minutes
◼ H2的IP地址是静态分派的
DHCP “plug-and-play” ■简化主机网络配置管理，方便接入 Host DHCP Relay DHCP Server DHCP-Discover DHCP-Offer DHCP-Request DHCP-Ack/Nack
DHCP “plug-and-play” ◼ 简化主机网络配置管理，方便接入
■当主机从一个交换机端口迁移到另一个端 口时，会重新发起DHCP过程，DHCP Discover与DHCP-Request均是广播方式， 这样有利于及时更新交换机的MAC地址表
◼ 当主机从一个交换机端口迁移到另一个端 口时，会重新发起DHCP过程，DHCPDiscover与DHCP-Request均是广播方式， 这样有利于及时更新交换机的MAC地址表
