各课程学习通信网理论基础netheory nettheory

1、平面:路由协议(RIP OSPF BGP)路由表数据平面:分组经路由表查再转发至出口Forwardin functions或MAframes或MAframes25 1 距离矢量5 2 链路状态路由5 3 MAC广播的生成树5 4 路由查找算法5 5交换路由34 BellmanFord算法 对加权有向图，计算源点去往一组(即vector)其他点最短距离和路径；负权回路时，无法解算完成；Richard Bellman无穷计数 (count-to-infi)问题；内循环次数：外循环次数： RIP|E|V|er Fo d Jr56d1d1EC311F261D3A4BRIPPort：520IPv4 Ad

2、dr.：224.0.0.9UDP IPNIF78192.168.5.1/24if (d1< t1 + a)d1 = t1 + adntndnDTDd2d2t1t2Bellm n, Richard O ating problem Quart. Appl. Math. ,1958, 16:8790.总循环次数：O(|E|V|)EC311F261D3A4B910ECEC331111FF226611DD33AA44BB1112V 192.168.5.1/24 D(V) = 0 + 1N 192.168.103.1V 192.168.5.1/24 D(V) = 0 + 1N 192.168.102

3、.1距离相等路径的解决1) 先到先用；2) 组播更新周期一半之前的优先。V 192.168.5.1/24 D(V) = 4 + 2N 192.168.105.1192.168.105.1192.168.102.1V192.168.5.1/24D(V) = infiniteN192.168.5.1192.168.5.1/24192.168.5.1/24192.168.102.0V192.168.5.1/24D(V) = 1N192.168.102.1度量值目标地址1个表项192.168.103.119224C92.168.5.1/231V 1 .1 8 .1 2V) = infiniteF219

4、 . 6110 .D3A4BV D(V) N.168.102.1 N 192.168.102.0 1314移动路线ECECCCFFDDAABBV CD(V) = 1D(V) = 1V BVCVCD(V) = 3D(V) = 2D(V) = 2ND15161 2 168.10 .0N BVCVCD(V) = 2NFVCD(V) = 2NF无线链路移动(mobile)Prob如此循环，以至无穷MANET: Mobile Ad hoc Network(IETF working group)68.5.1/24N192.168.5.1V92.168.5.1/24D( ) 1N1 2.168.102.1(

5、V) = 0EECCFS1VD(V) = 2DAVCV) = 1BVCVCD(V) = 1D(V) =2N D 10 SN1117185.1 距离矢量路由5.2 链路状态路由5.3 MAC广播的生成树EC192.168.5.1/2431V 192.168.5.1/24D(V) = infinite1F2192.168.102.1136NDA5.4 路由查找算法4B5.5VD(V)交换路由N192. Prob如此循环，以至无穷1920192.168.102.068.5.1/24.168.102.0192.168.5.1V192.168.5.1/24D(V) = 1N192.168.102.1cl

6、7v/cs851-papers/dsdv-sigcomm94.pdfSN 11 SNVCD(V) = 3NBSN11SN0VCD(V) = 2NFSN10移动路线DV0CS192.168.5.1/24EC311F61D3A4B2122DV0CS192.168.5.1/24EC311F2613DA4BS192.168.5.1/242324192.168.5.1/24192.168.102.0192.168.5.1/24192.168.5.1/24D10VDCD10VFCD10VFCSD10VDCS 192.168.5.1/24E13EC311F261S1 2 11/243DA4B2526Inpu

7、t: Graph (N,E) withthe set of nodes and E Í N × N the set of edgesNdvw slink cost (dvw = infisource node.if (v,w) Ï E, dvv = 0)Output: DnM = s;for eachcost of the least-cost path from node s to node nn Ï MDn = dsn;while (M ¹ all nodes) doFind w Ï M for which Dw = minDj

8、; j Ï M; Add w to M;for each n Ï MDn = minw Dn, Dw + dwn ; Update route;enddo2728A 集路状态D1VFDV1D0CS192.168.5.1/24E,BE,B,FE,B,F,CE,B,F,C,Dstep1step2step3step4step5BCDEFS4667772222265555664444VCS192.168. . /24Unicast-Routing Protocol forMANET (Topology-based)EECFDAB 2）删除已选的MPR及对应的2跳节点 3）重复1）和

9、2），甚至所有2跳节点全部删除321）连接2跳邻接节点最多的单居源自C的L消息总数为8条Table-Driven/ Proactive源自C的OLSR消息总数为5条所以，节能3/8Prob节点D为MPR(M lti-Point Relay)负责2跳的单跳邻近节DSDVOLSRTBRPFFSR STARLANMAR CEDARDSR AODV TORAZRPDistance- VectorLink- StateClusterbased/ HierarchicalOn-Demand- driven/ReactiveHybrid5 1 距离矢量5 2 链路状态路由5 3 MAC广播的生成树5 4 路

10、由查找算法5 5交换3336192.1 8.5.2B(o ) 与网络中间L2交换机1）以广播方式，效率极低/可扩展性极差.3通过 IP 分组互通MID：multiple interface declarationTC：Topology ControlBobEC311F2 t1=1 61 t2= 1+1D3A4B 广播永远不终止3738BobEC311F2613DA4B t1=1+6=7 t2=1+3+5=9t5=1+3+1+3+2=10 t4=1+1+4=6 3940Prob如何阻断广播回路?(ob) 与 A( ice) 通过 IPt3=1+3+4=8192.168.5.3192.168.5.

11、2.168.5.3192.168.5.3网络中间L2交换2） 以单播方式，要求学习并相互交换转发MA 地址3） 端 点，一定要询问到特定IP地址对应的MAC地址192.168.5.28.5.2BobEC311F2611953DA4B规则：不为根的L2发送Hello消息所以，F不以根发送Hello4142BobBobECEC331111FF226611DD33AA44BB规则：L2转发Hello消息，并附加至根的成本4344对于F：w(A,E,F)=2+3=5 w(A,F)=6w(A,B,F)=5相同成本，以ID最小，即B，为父Perlman R. An algorithm for distri

12、buted computation of a spanningtree in an extended LANC. ACM SIGCOMM Computer Communication Review, 1985, 15(4): 44-53.A作为根发出的Hello被F转发给C192.168.5.3192.168.5.3不再间通过HELLO消息通告ID、成本和链路ID2) 选取根端口L2至根成本最小的端口4) 确定指定端口L1经该口至根最小的端口Bob1F261D33AAli4B454695088464529153834748业务流临时转移到MSPT(1)MSTP(0)如果(A,E)和(A,B)链

13、路中断192.168.5.3：(B,F), ( ,D)为指定端口F(F,C)为指定端口.25.1 距离矢量路由5.2 链路状态路由5.3 MAC广播的生成树5.4 路由查找算法5.5交换路由平面:运行路由协议( IP, O PF, BGP)数据平面:技1)查找速度（最坏/平均）将分组寻址转发到出口2)空间大小3)更新速度5152根节点度不大于2，中间节点度不大于3， 叶节点度为1。53545556int Looku (Nod *r, IPAdd addr, i t o = 0) n retifaddr<<of)>> 32 of) &&>right)

14、 ret = Lookup(&(*r)->r ght), addr, + f)if (! (addr<<of)>>( 2- f) && (*r)->le t ret = o up(&(*r)eft) addr, +of);i ( et = - ) ret = (*r)->portIndex; eturn ret;Insert( ode *r, int p rt, IPPref p ef, i t f0) if (* = N LLr = new Node(0,0,-1 ;if (of se >= pref.(*r)-

15、>portIn ex = port; lse f ( (pref.ad r << of >> (32 o r = &(*r)->right);l er = &(*r)->leInser (r, p rt, p ef, +of);struct IPPre int8 len int32 d r;struNode *lef ; Node *right int32 portIndex; *root;struct IPPref nt8 len;i t32 a r;structode *left; ode *right;i t32 portInde

16、x; *r平衡二叉树：除外，节点度均为3585960Prob设计更新和查找 序单分支路径单分支路径增加匹配位6364T(us)S(Mb/s)620003.534291.580000.524000平均分组查 时间最长分组长度L1500B12000b吞吐能性：L/TProb如何缩小缺口路由器端口数：N100端口宽带：BW10Gb/s最低吞吐性能：S1000Gb/sRuiz-Sánchebous W. Survey and taxonomy of IP address lookup ahmsJ. Network, IEEE, 2008-23.5.15.2 链路状 路由5.3 MAC广播的

17、成树5.4 路由查 算法5.5交换路由6768100个端口、32位长地址， 最多需要3200个TCA含6400个SRAM单元LSR1O tO tLER出口LERL1L2L3RUTAT E GE, SW TCIN CORE72按Q 现状预分配IPIPIPIP ForwardingL BEL SWITCIP ForwardingP#L3#L2#L1IPP：有QoS保障Pr 中间链路不能保证Q S152DA1测度m <M、跳数最小路径7576式521B785.1 对比分析RIP与 SPF协议的异同点。5.2 如何解决LS路由的无究 数问题？5.3 实验观测并报告交换机自环前后的网络 量变化。5.4 设计PATRICIA路由表的更新和查找代码。5.5 给出Bel