OSPF的cost值累加计算

1、OSPF的cost值累加计算OSPF以cost值为路由的度量值，cost值是从源到目的所有出接口的累加开销值，可手工修改。一、拓扑R1、R2、R3的接口都在area 0中。各台路由器默认接口 cost值。链路类型cisco默认开销IEEE修订IEEE旧版以太网（10M）10100100快速以太网（100M）11910吉比特以太网（1G）14110吉比特以太网（10G）1212.1、R1Rl_IOL#5h Interf are EtO a EtU/UPDOOs IG &o P11 nterface briefAreaIP Address1 ask0/24Ul.l.l.L/2Dooellstate

2、 Nbrs F/cDR C/0DR 1/12.2、R2R2_lOLsh interface E LO，2L ELO/O K2_1UL#-PD o o5 I & oo p 1 1ntcrf ace br i ef Ar ea 0 0IP AddrEss/pask2.1.1. 2/24/24StateR ELXCU? 3 br/1/1 Nil2.3、R3R-TOUhTn-prfatpEt3/1Et3/CR3_I0U#c.p PTD 100 100nt prfatpAr pabri pfTP/24/24St ATP NWS F/CDR 0/0BDR 1/1三、访问关系3.1、数据包以R1为源，PC2

3、为目的，进行ping的访问操作计算路由及累加cost值。3.1.1、cisco默认cost配置的累加值：R1到网络的累加cost值30。Rl_IOL#ih code: _ -J -二ip rcute os af1 ocal , C - connected, 3 - stafi c,壬-FLIP, M - mob-1e, D - GCPLLtiKF, LX - LitiF external , u -. ia - ubFi- 1 niEr ar ea-nspp jssa pxrp-nsl -ypp 1 , N? - opf nssa PKternal type ?-ospr Ktcnal typ

4、e 1, EZ2 - osnr external type 215-15, iu - 15-15 iunmdry, Ll - 15-15 1evel-1, L2 - 15-15 level-Z -is-is 1 nter area, * - candidate detauIt, u - per-use- statlc route DRs P - per-odi c downloaded statd e roue ? H - NHRP, 1 - LISP repUcated route, % - rexi boa ovet-ceGfltpwy nf Iast rpsnrt -s not spT2

5、. 0.0. 3；24G2.L.1.U6一 0.0.9/?4CKL_10L#：4J:04.Liherneiu/u.EihcrnctO/Oi i jbntLLed niu/zoi via i s s.ibnprr pd 110/30 v-i a,1 aubriet.、1.1.1.z, uu,1 subnet?;, 00计算 cost 累加：R1 e0/0+R2 e0/1+R3 e0/1 =30对应： 10+10 +10=30220验证：通过修改R3 e0/1的cost值为200。预测R1到/24网络的cost值应为配置:RB-IOUih r un i _iL eOl bdi 1 dlnq con

6、flqjratl an.Current conf i guratiioni : Bl bytes interface EthernetO/1Ip address 6.1.1-3 ip ospf cost 200end验证结果：正确。-|- Rl_iou5i Jp route ospfcudti: L - luLdl , (_ - Lunr tLLtu, b - LdL i l , R - RF, N - mub i 11, b - EiGP D - PTGHPr FX - FTCR= PtPrnA I , Cl 一 flSPF, TA - C-S = F IntPr ArPA N1 - OPP

7、 NSA extemaI type 1, N2 - OPF NA external type 2 El - O5PF external type 1, E2 - 05PF exterral type 2i - ib-ib, 5ii - li-ib summary, li - ib-ib level-1, lw - it-n level-2 na - TS-TS i nrpr appa , * - rndi riAtp ripfaiilr, Ll - ppr-.jpr Ti r rnu-p o - GDR, P - peri odi c doinl oaded 5tatic route, P -

8、 Nl-R。， 1 - LIEP + - r epl icaLtd ruule, % - nexL hep uvtrT i dtof Iart rpf；orr is nnt s;prIIIC/23 vlal.1.1.2, 00:52:56. Ether net0；0 is subnetted. 1 subnets110/220 via 1.1.1. 2, 。：M:55, EthernetO/O2.0. 0.024 i i iubiielLEd . 1 iubMELi e 一技砰6粕 G.1.1.0四、结论。当明确了源与目的IP的访问关系，从路由器的角度，cost值是从源到目的所有出接 口的累加

9、开销值。在R1看来，到达PC2的网络（）, cost值是从源到目的所有出接口的 累加开销值，也就是R1_e0/0+R2_e0/1+R3_e0/1的 cost 值。反之亦然。R3_lOU；Vsh 1 p route ospCodes: L - local , C - came ct cd, 5 - stati c,玲-RIP, F - mab-le, C - GCP D - EzlGKP, LX - L1GRP tXLtfF fldl , O - O咨，A - DbFF i nltzF N1 - 35PF 幅 SA external type 1, N2 - OSPF NS SA extEmal

10、 type 2 F1 - nspp pxtprnAl typp 1 . P? - OSPF pxTprnal typp ?i - IS IS, gu - IS I summary, Ll - IS I 1cvcl 1, L2 - 15 I 1cvcl 2 da- 15-15 i nter area. * - can eld daLE default, U - pe- -use- staLi c - oute u - ODR. F - per i ud i l uuwnluddtd i l r uuLe, H - NTFtP, 1 - LLiP + - repilcatec route, % - hexl hop ove-r_ceGatEway of last resort i s not set1. 3.