浅谈VLSM划分子网的技巧

在网络工程的设计与建设中,经常要用到IP地址的分配与设置。为节省IP地址的使用,大多采用子网划分的方法分配内部IP地址,根据是否改变子网掩码的长度,子网划分可以分为固定长度子网掩码的划分方法和可变长度子网掩码的划分方法,由于后者能够更加高效利用IP地址资源,所以得到广泛应用,但又因其计算过程比较麻烦,实际应用中经常出错,成为学习和应用IP地址过程中的＂瓶颈＂,本文主要介绍可变长度子网掩码划分子网的技巧,以便提高分配IP的效率。     

子网划分方法研究

子网划分就是把单一的IP网络划分为几个物理网络。划分子网可以提高IP地址的利用率,提高网络的安全性,易于管理网络等。为了寻求划分子网的简易方法,通过对什么是子网以及对子网掩码作用的分析和理解,阐述了划分子网的基本思路,如何确定子网掩码,如何得到网络地址和主机地址,总结了划分子网的简易方法及一般步骤,并用实例进行了说明。从而解决了已知子网数或主机数划分子网的方法。     

高校校园网络IP地址设计规划解析

文章针对高校校园网IP地址密集且易冲突的特性指出,在设计IP地址方案之初,应考虑以下问题:为方便管理网络计划划分多个子网;在连入因特网后是否使用真实的网络地址;每个子网信息点的计划划分多少,将来要拓展多少;子网IP地址的分配是采用静态分配或者选择动态IP。还可以用另一个IP地址来代替TCP报头里的IP地址,此法可以由NAT技术解决。     

IP地址子网划分和VLSM划分的易语言算法研究

计算机网络地址的合理分配和充分利用可通过IP地址子网划分和VLSM划分技术来实现。依据子网划分和VLSM划分原理,文章研究了用易语言中文编写的子网划分和VLSM划分算法。经手算和易语言算法计算结果表明,该算法能高效准确的实现子网划分和VLSM划分。     

子网的规划及划分

随着网络技术和信息技术的迅速发展,越来越多的单位和家庭将计算机接入到互联网上,因大部分用户不是网络专业技术人员,很少能合理地使用IP地址,为了节约IP地址和便于管理网络,提出了一种子网的规划及划分的方法。这里对子网编址的方法进行了介绍,并根据实例对子网规划的设计过程进行了分析。通过实验,在内部局域网上划分逻辑子网,从而减少了IP地址的浪费。实践证明,该方法操作方便,可靠性高,具有一定的实际应用价值。     

基于CIDR的网络划分方案

分类IP存在着地址严重的浪费现象,划分子网不能解决主干路由表过长的问题。CIDR将IP地址由3级又回到了两级,降低了主干路由表的长度,提高了地址分配的灵活性。     

IP地址与子网划分的教学方法研究

掌握计算机技术已经成为未来社会人才竞争中的主要能力之一,高校纷纷开设计算机网络基础课程,以便为社会输送更多优秀的计算机人才。在实践教学中,由于教师所择的教学理念和教学方法较为陈旧,所以学生很难有效理解和记忆。基于此,文章主要就计算机网络基础课程中IP地址与子网划分的教学方法进行研究,需要教师根据学科特色,选择合理的教学方法,帮助学生更充分了解IP地址与子网划分内容。     

Cable Modem系统应用设计

本文总结了Cable Modem系统的原理和CMTS的关键功能，系统介绍了南京电视台Cable Modem系统的设计思路和设计方法。采用源IP地址路由技术实现了用户子网划分和区分服务，并且支持基于Cable Modem系统的专网接入业务。     

IP地址的规划和路由的配置

为使广域网在划分子网时，进行合理的IP地址的规划和路由配置，实现高效的资源分配和连通效率。     

VLAN的局限性及其发展

传统VLAN(Virtual Local Area Network)存在IP地址浪费和安全性的问题。本文分析讨论了VLAN在这两方面的问题，并总结归纳了这两个方面问题的解决方案-Super VLAN和Private VLAN技术。Super VLAN将多个VLAN对应于一个IP子网，从而建立一个更加有效的IP地址分配体系；Private VLAN技术引入三种类型的端口和两种类型的VLAN，将同一IP子网内的流量在二层隔开，从而提高了网络安全性。     

SEAL2: An SDN‐enabled all‐Layer2 packet forwarding network architecture for multitenant datacenter networks

This paper presents the design and development of a new network virtualization scheme to support multitenant datacenter networking (MT‐DCN) based on software‐defined networking (SDN) technologies. Effective multitenancy supports are essential and challenging for datacenter networking designs. In this study, we propose a new network virtualization architecture framework for efficient packet forwarding in MT‐DCN. Traditionally, an internet host uses IP addresses for both host identification and location information, which causes mobile IP problems whenever the host is moved from one IP subnet to another. Unfortunately, virtual machine (VM) mobility is inevitable for cloud computing in datacenters for reasons such as server consolidation and network traffic flow optimization. To solve the problems, we decouple VM identification and location information with two independent values neither by IP addresses. We redefine the semantics of Ethernet MAC address to embed tenant ID information to the MAC address field without violating its original functionality. We also replace traditional Layer2/Layer3 two‐stage routing schemes (MAC/IP) with an all‐Layer2 packet forwarding mechanism that combines MAC addresses (for VM identification and forwarding in local server groups under an edge switch gateway) and multiprotocol label switching (MPLS) labels (for packet transportation between edge switch gateways across the core label switching network connecting all the edge gateways). To accommodate conventional IP packet architecture in a multitenant environment, SDN (OpenFlow) technology is used to handle all this complex network traffics. We verified the design concepts by a simple system prototype in which all the major system components were implemented. Based on the prototype system, we evaluated packet forwarding efficiency under the proposed network architecture and compared it with conventional IP subnet routing approaches. We also evaluated the incurred packet processing overhead caused by each of the packet routing components.     

自治系统内IP子网和SDN子网的互联机制

SDN网络与传统IP网络的互联机制是当前学术界的研究热点,但现有解决方案并不能适用于所有应用场景。为此提出了一个基于OSPF协议的IMISA架构,在一个包含 SDN 子网（基于OpenFlow）和IP子网的自治系统范围内,通过给SDN控制器添加一个OSPF路由模块,利用OSPF协议交换各自的网络信息,最终实现了2种网络的互联。     

Modeling node mobility for reliable packet delivery in mobile ip networks

In this paper, we analyze node mobility for reliable packet delivery in mobile IP networks. In mobile IP, packets destined to roaming nodes are intercepted by their home agents and delivered via tunneling to their care of addresses (CoA). A mobile node may roam across multiple subnets. At each boundary crossing, a handoff is initiated such that the CoA is updated and a new tunnel is established. We consider both basic mobile IP handoff and smooth handoff. We find that reliable packet delivery in mobile IP networks can be modeled as a renewal process, because the retransmission over a new tunnel after each boundary crossing is independent of the previous history. We then derive the probability distribution of boundary crossings for each successful packet, based on which the packet reliable delivery time can be obtained. Our analytical model is derived based on a general distribution of residence time in a subnet and a general distribution of successful retransmission attempts in each subnet. The results can be readily applied to any distributions for both items. We also provide numerical examples to calculate the probability distribution of boundary crossings, and conduct simulations to validate our analytical results     

Authenticated Ad Hoc Routing at the Link Layer for Mobile Systems

We have designed an authenticated link-level ad hoc routing protocol and integrated it with the Portland State University implementation of Mobile-IP. The routing protocol addresses link security issues. In our protocol, mobile nodes, as well as agents, broadcast ICMP router discovery packets. The router discovery packets are authenticated and bind the sender's MAC and IP addresses. Problems caused by tying IP subnet schemes to routing on radio links are eliminated. Security problems associated with ARP spoofing are also reduced. This link-level protocol is integrated with Mobile-IP on links where increased security is needed. The protocol replaces ARP, and may be integrated with higher-level multi-hop ad hoc routing protocols.     

Multicast delivery based on unicast and subnet multicast

In spite of the numerous works previously made, IP multicasting has not been widely deployed in the public Internet. We present a realistic alternative scheme for IP multicasting, which is based on the unicast transport from a remote sender to a local subnet and the multicast forwarding to receivers within the subnet     

基于IPoverTS系统网段内地址扩展技术的研究

针对IPoverTS系统研究同一网段内的地址扩展技术,分析常用的链路扩展方法,在无线链路传输中针对该方法所导致的信道有效占有率不稳定且不足提出邻接表法。为了增强邻接表法的地址扩展灵活性将邻接表法改进为自适应邻接表法。测试结果表明,自适应邻接表法解决了同一网段内的地址扩展问题．同时提高了无线信道有效数据的占有率和稳定性。     

基于子网模型的运营商移动存量用户保有方法

移动市场已进入存量发展模式,对运营商存量用户保有提出了更高的要求。不同于传统针对单个用户“合约式”的保有策略,本文在社会网络概念的基础上提出基于子网模型的用户保有方法。引出了通信子网、黏性子网概念,构建了同质性子网、异质性子网和易感节点模型,为运营商存量用户保有提供新的思路。     

基于VMware虚拟网络技术的DHCP服务器实验设计

在教学过程提出了一种基于VMware虚拟网络技术实现DHCP中继代理的设计方案。使用VMware构建虚拟网络环境,然后在WindowsServer2003中安装DHCP服务,配置路由和远程访问服务来实现不同子网之间的路由,并能为不同子网的客户机动态分配IP地址。最后,对该设计方案进行了测试。