Category Archives: Network

# Simple lab #Two networks are established by using the following Cisco routers. One network is for WEB application. The other is for production application.   [localhost] #load images that may be used for new topologies#configure hardwares as you wish#the … Continue reading →

Dynamips is awesome:) By using VM software, you can build a "real" virtual network testbed based on Cisco devices. The testbed is "real" because the virtual Cisco routers can use your real network interface.:) 1. install following softwares/libs for Dynamips-Dynagen … Continue reading →

http://telecom.dei.unipd.it/ns/download/nsmiracle-2.0-beta.tar.gz

被论文折磨的很痛苦，干脆停下来，灌个水贴。IEEE802.11标准可谓一座摩天大厦，我们的动机就是花费一年人时给这个摩天大厦的缩微模型做一个小螺钉（跨层监控）。常常想，能不能给个做下去的理由先？IEEE802.11的任务组TG可谓蚂蚁搬家，十年来把无线局域网做到了百兆带宽（IEEE802.11n），所用时间和有线以太网类似，考量无线的复杂性，真是不容易。 26个字母的TG头疼医头，脚疼医脚，遍地开花，以致即将用尽，想想来自全世界的工程师为此忙碌，也是很有趣的事情。IEEE802.11n的理论峰值达到600Mbps，市面上已有300Mbps的产品。而IEEE802.11s即将网络扩展到城域接入网范围。MIMO已做到4X4，快速漫游，远程网状网，定向/智能天线，认知无线电网络技术正在发展，百兆有线以太网和综合布线的大限似乎来了。带宽1Gbps的研究组已经成立，无线交换，无线VPN开始启动。再想想指甲大小的芯片组，呵呵，能实现无线接入交换的IEEE802.11是否会和包交换结合组建下一代宽带通信网，可真难说。比如最简单的例子，如果每个移动终端能分配到2Mbps以上的带宽，电信公司估计都要换skype大旗了。移动宽带会将网络应用推到极致，如此的美妙前景，能不能支撑我完成那个该死的螺丝钉！

SNR: Shannon Limit: DSSS: HR/DSSS: PLCP: PMD: OFDM: CCA:Clear Channel Assessment—-ED:energy detection (if the value > the threshold, WM is busy)   CCA:Clear Channel Assessment—-P-CS:Physical Carrier Sense  RSSI: receive signal strength indicator (8bits, 256 levels, 0-255, measured as mW or dBm … Continue reading →

CW:contention windowRTS/CTS: request to send/clear to send (The hidden station problem never occurs in 802.11, this function is disabled by default) DCF:distributed coordination function (via CSMA/CA and a backoff technique)CSMA/CA:IFS:interframe space SIFS:short interframe space (for ACK,CTS,the second or subsequent MPDU of a … Continue reading →

http://books.google.com/books?id=8wvfAw6_Tq0C&printsec=frontcover&dq=802.11+WLAN+Hands-On+Analysis:+Unleashing+the+Network+Monitor+for&client=firefox-a&sig=ACfU3U3QHpotODeCm05MmR_YS8TNC2EPBA CDMA/CA:physical carrier sense;dynamically CW with exphonetial back-off algorithm;virtual carrier sense; Received Frame Acknowledgment( a positive Ack ) : Unicast frames must be Acked; Broadcast frames transmitted by a STA are acknowledged by the AP and then processed by the … Continue reading →

http://www.ece.rice.edu/~jpr/ns/docs/802_11.html MAC frame的格式可参考IEEE STD 802.112007或以下连接：http://technet2.microsoft.com/windowsserver/en/library/370b019f-711f-4d5a-8b1e-4289db0bcafd1033.mspx?mfr=true mac-802_11.h:// frame control field:struct frame_control {    u_char        fc_subtype        : 4;    u_char        fc_type            : 2;   //frame type : RTS, CTS, ACK, data    u_char        fc_protocol_version    : 2;     u_char        fc_order    … Continue reading →

http://networks.rice.edu/papers/ networks.rice.edu/papers/mesh80211s.pdf congestion control: local congestion control signaling 拥塞节点通知相邻节点发生拥塞，邻居节点对其调整速率。 1.the transit queue size : the diffrence between aggregate packets received and transmitted at MAC.   congestion detecting: probability p=(q-tl) / (tu-tl) .q is queue size, tl and tu are lower and … Continue reading →

module的主要功能就是利用sap实现上下各层模块的通讯。nsmiracle可以根据需要在各层定义不同数量的模块,所以定义节点时如同搭积木一般灵活。每个module class还通过clsap和nodecore相连以实现跨层消息传递。 #ifndef MODULE_H#define MODULE_H #include "plugin.h" /** * The MODULE class is a PlugIn which is forced to be in a stack * It may have several connections both to module(s) of the up layer in the stack (through SAP) * and … Continue reading →