Figure 523 The routing table of RTC in Figure 520

ip roucc

£uju!h: C connected, S static, I ■ IGRP, H. ■ K1H, U mobile, U Sti?

Li EIGBP, EX EIGRP external, 0 OSPF, [A l*,£.f>f inter ares Hf LJSt^F NSSA external type 1, n? uspf rtsSA nkternni type ? L1 QSPI external type 1 , E2 ■ (JSP? exit "rial tysc 2, L LiiP

1 IS IS, Li ■ IS IS level-1J L2 IS IS level 2, - - candidate default

U per user static route, o ofm

Gateway er last resort is not set

172.16.0,8/23 is Subrtettefl, -1 autinuts c 172. IN.a--,.u is directly corrected, Serial^

R 17?.16.26.0 | 120 1 I Via * 7?. . 16. 24. 2. 04:00:03, 3cr;nlH

n 172.1 a.20.0 1120 lj via "72.16.10.5. 00:89:25, Ethernets

C 172.16.18.0 is directly connected, Ethernets fiTC*

3: Users on subnet 172.16.18.0/23 in Figure 5.20 are complaining that connectivity to subnet

172.16.26.0/23 is intermittent—sometimes it can be reached, sometimes it can't. (The bad subnet masks of RTB have been corrected.) A first examination of the routing tables of RTC and RTD (Figure 5.24) seems to show no problems. All subnets are in both tables. Yet a minute or so later, RTC shows subnet 172.16.26.0/23 to be unreachable (figure 5.25), whereas RTD still shows all subnets. A few minutes after that, the subnet is back in RTC's routing table (Figure 5.26). In each of the three figures, the routing table of RTD shows no change. A careful examination of the routing tables in Figures 5.24 through 5.26 will reveal the problem. What is it?

Figure 5.24. The routing tables of RTC and RTD in figure 5.20

Figure 5.24. The routing tables of RTC and RTD in figure 5.20

Figure 5.25. The routing tables of RTC and RTD ,examined approximately 60 seconds after figure 5.24

Figure 5.26.

The routing tables of RTC and RTd,examined approximately 120 seconds after figure 5.25

Cedii: t tonneetiFd, s sunt, l iGflp, h rih, u mobile, Ei hü?

u LIQfip, LX LlüHP r.'Ai ernal, D DS-Pr , IA OliPf inter nrtn

:|l CSPJ >IBSi. external tvuc I, Mi üüPh My SA external typa 2

ii 05« enteral type l, ! ? hüpi internal ivn'1 E ■

i IS iü, L- level ■, L2 level 2, * ■ candidate default, l. torusor ^liitj-:. ¡'tut'!, o - oiiH

172.16.fl.e/23 i^ subnattad, 5 subnets v 172,10-14,9 ii directly tonivieurf, senaie

R 17Z.1G.2B.B !1S3.'1| Jl.l 1 72 . IB .24.2, 00:B0:B9, SerlalB

Ii 172.1G m e I1MMI via 17S. ■ Fi. IH.6, W:M:1i. Ethernati

R 1 72.1(5.J?.(1 I 1 r-a-■ 1 I via 172. Ti.lH.11. 18, EtlwneTfl

'J 172.1C.18.B la directly connected, EthernetB

RTDiWBhcjw ii rout«

CDdsil C ■ tonnected, 5 -itiiut;, L Lüh?. h mh, U mobile, S Uü^ £ I [idfip, IX EI6HP 4«(4ri>4i, 0 n%PI . IA DKPi inter are*

LI ■ USI'I e* te^nal type 1. 12 external tyüL- 2. E LGF1

; ii; i p.. I ■. ■ ii is level 1. is IS Lival 1, * ■ candidate dsfault, L. por user static rout*

Gateway or last resort is not set

171,16.e,s;is is 3ubneti»d, 5 subums C 1 72.1 r,.2-1.0 li. directiy üün^r.'Ctid, Sarlale

C 172,i6.ii.Ci is directly i-onfteeted, FekenFUUBa

R 172.ie.2i-8 |12QJ2| via 173.18.34.1, 19, Serial!)

ft 172.ie.i2.il |12flf2| via 172,15,24,1, 00:00119,, SerlalB

R 17J,10.18-i MMJll via 1 TS. 16.34,1, M:60;1O, Serial i

0 0

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