[Xorp-users] cannot ping one of the interfaces from an OSPF router after installing XORP
Ben Greear
greearb at candelatech.com
Tue Aug 5 08:45:34 PDT 2014
On 08/05/2014 08:32 AM, Liu, Xuan (UMKC-Student) wrote:
> Hello,
>
>
> I have came across this problem when I have configured a simple five-node network running OSPF protocol. The topology looks like
>
>
> 1 --------------- 2
>
> / \ / \
>
> / \ / |
>
> 4 \ / 3
>
> | \ / |
>
> \ \ / /
>
> \ \ / /
>
> \------ 5 -----/
>
>
> The link information is : rt1:eth4 -- rt2:eth1: 192.168.1.1 - 192.168.1.2
>
> rt2:eth4 -- rt3:eth3: 192.168.6.1 - 192.168.6.2
>
> rt3:eth2 -- rt5:eth2: 192.168.10.1 - 192.168.10.2
>
> rt5:eth1 -- rt4:eth3: 192.168.13.2 - 192.168.13.1
>
> rt4:eth2 -- rt1:eth2: 192.168.2.2 - 192.168.2.1
>
> rt1:eth3 -- rt5:eth3: 192.168.3.1 - 192.168.3.2
>
> rt2:eth2 -- rt5:eth5: 192.168.7.1 - 192.168.7.2
>
> All link has prefix 24.
>
>
> Each node runs Ubuntu 12.04 OS, and I have installed XORP 1.8.5. For each node, I have configured it as an OSPF router. Most of the routing looks fine to me,
> except for some interfaces. For example:
>
>
> If I send ping request from rt1 to 192.168.7.2 (rt5), I got no response. The routing table at rt1, rt5 are like:
>
>
> root at rt-1> show route table ipv4 unicast ospf
> 192.168.6.0/24[ospf(110)/20]
>> to 192.168.1.2 via eth4/eth4
> 192.168.7.0/24[ospf(110)/20]
>> to 192.168.1.2 via eth4/eth4
> 192.168.10.0/24[ospf(110)/20]
>> to 192.168.3.2 via eth3/eth3
> 192.168.13.0/24[ospf(110)/20]
>> to 192.168.2.2 via eth2/eth2
>
>
>
> root at rt-5> show route table ipv4 unicast ospf
> 192.168.1.0/24[ospf(110)/20]
>> to 192.168.3.1 via eth3/eth3
> 192.168.2.0/24[ospf(110)/20]
>> to 192.168.3.1 via eth3/eth3
> 192.168.6.0/24[ospf(110)/20]
>> to 192.168.10.1 via eth2/eth2
>
>
> I ran tcpdump at rt1, rt2 and rt5 and found that
>
>
> At rt-2 eth1:
>
> xuanliu at rt-2:~$ sudo tcpdump -i eth1 icmp -n
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes
> 11:22:58.797404 IP 192.168.1.1 > 192.168.7.2: ICMP echo request, id 11873, seq 265, length 64
> 11:22:59.805624 IP 192.168.1.1 > 192.168.7.2: ICMP echo request, id 11873, seq 266, length 64
> 11:23:00.813283 IP 192.168.1.1 > 192.168.7.2: ICMP echo request, id 11873, seq 267, length 64
> 11:23:01.821354 IP 192.168.1.1 > 192.168.7.2: ICMP echo request, id 11873, seq 268, length 64
>
>
> At rt-2 eth2:
>
> xuanliu at rt-2:~$ sudo tcpdump -i eth2 icmp -n
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on eth2, link-type EN10MB (Ethernet), capture size 65535 bytes
> 11:24:08.347513 IP 192.168.1.1 > 192.168.7.2: ICMP echo request, id 11873, seq 334, length 64
> 11:24:09.355769 IP 192.168.1.1 > 192.168.7.2: ICMP echo request, id 11873, seq 335, length 64
> 11:24:10.363503 IP 192.168.1.1 > 192.168.7.2: ICMP echo request, id 11873, seq 336, length 64
>
> At rt-5 eth5:
> xuanliu at rt-5:/usr/local/xorp/sbin$ sudo tcpdump -i eth5 icmp -n
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on eth5, link-type EN10MB (Ethernet), capture size 65535 bytes
> 11:24:52.122424 IP 192.168.1.1 > 192.168.7.2: ICMP echo request, id 11873, seq 376, length 64
> 11:24:53.130022 IP 192.168.1.1 > 192.168.7.2: ICMP echo request, id 11873, seq 377, length 64
> 11:24:54.138424 IP 192.168.1.1 > 192.168.7.2: ICMP echo request, id 11873, seq 378, length 64
>
> Based on the routing table at rt-5, the packet to 192.168.1.0 should be forwarded to link 192.168.3.0. So I checked the interface rt-5:eth3, and it showed nothing.
>
> xuanliu at rt-5:/usr/local/xorp/sbin$ sudo tcpdump -i eth3 icmp -n
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on eth3, link-type EN10MB (Ethernet), capture size 65535 bytes
>
>
> Similarly, I couldn't ping rt-5:eth1 (192.168.13.2) from rt-1 neither. But I can ping 192.168.10.2, and 192.168.10.1, and the packets were forwarded from
> rt-5:eth3(192.168.3.2) to rt-5:eth2(192.168.10.2)
>
>
> Could you please provide any suggestion on how to troubleshooting this problem?
Use xorpsh to print out the neighbors on rt-5, make sure your configuration interface
is correct, look at the xorp logs to see if it shows any obvious errors, etc.
Thanks,
Ben
>
>
> Thanks,
>
>
> -- Xuan Liu
>
>
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>
--
Ben Greear <greearb at candelatech.com>
Candela Technologies Inc http://www.candelatech.com
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