From: Cheung, Tom [JJMI-AR] (TCHEUNG@xxxxxxxxxxxxx)
Date: Thu Oct 12 2000 - 16:47:50 GMT-3
Title: FW: routing problem
All,
I have a general routing question. Here's the scenario:
serial serial
r5 ---------------------- R1 ------------------> frame cloud
172.17.59.64/26 (IGRP) 172.17.59.x (OSPF, VLSM)
On OSPF side 172.17.59.x is variable subnetted into /28, /29 and /30.
I injected the OSPF routes into IGRP by "summary-address 172.17.59.0
255.255.255.192"
From R5, I'm able to ping 172.17.59.5, 59.9, 59.17 etc. but was unable
to ping 59.193. It is "unroutable".
My explanation to why 192.17.59.193 is "not routable" is that R5 knows
only 172.17.59.0/26 and 172.16.59.64/26. 192.17.59.192 is not a
192.17.59.0 subnet. Therefore R5 drops packets for 192.17.59.193. But
then, shouldn't "ip classless" force the router to do longest match
and find 182.17.59.0 for 59.193?
R5's show ip route, debug IP packet output during the ping fail are
attached for your reference.
[r5#
r5#sh ip ro
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B -
BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * -
candidate default
U - per-user static route, o - ODR
Gateway of last resort is not set
172.17.0.0/26 is subnetted, 2 subnets
I 172.17.59.0 [100/159250] via 172.17.59.65, 00:00:17, Serial0
C 172.17.59.64 is directly connected, Serial0
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.2.0 is directly connected, Ethernet0
r5#
r5#
r5#deb ip packet
IP packet debugging is on
r5#ping 172.17.59.193
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.17.59.193, timeout is 2 seconds:
00:11:20: IP: s=172.17.59.66 (local), d=172.17.59.193, len 100,
unroutable.
00:11:21: IP: s=10.1.2.1 (local), d=255.255.255.255 (Ethernet0), len
52, sending
broad/multicast
00:11:22: IP: s=172.17.59.66 (local), d=172.17.59.193, len 100,
unroutable.
00:11:24: IP: s=172.17.59.66 (local), d=172.17.59.193, len 100,
unroutable.
00:11:26: IP: s=172.17.59.66 (local), d=172.17.59.193, len 100,
unroutable.
00:11:28: IP: s=172.17.59.66 (local), d=172.17.59.193, len 100,
unroutable.
Success rate is 0 percent (0/5)
Tom
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