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  • traceroute issue

    Posted on

    Hi experts,

    I met an issue regarding traceroute.

    When I set default route, I can trace all paths.

    [root@localhost ~]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         192.168.44.2    0.0.0.0         UG    0      0        0 eno16777736
    169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eno16777736
    192.168.44.0    0.0.0.0         255.255.255.0   U     0      0        0 eno16777736
    
    [root@localhost ~]# traceroute -I 172.25.252.129
    traceroute to 172.25.252.129 (172.25.252.129), 30 hops max, 60 byte packets
     1  192.168.44.2 (192.168.44.2)  0.089 ms  0.057 ms  0.045 ms
     2  172.27.226.254 (172.27.226.254)  36.412 ms  36.620 ms  36.645 ms
     3  172.25.252.129 (172.25.252.129)  24.081 ms  24.685 ms  24.663 ms
    

    If I do not set default route but using static routes, I can not trace all paths.

    [root@localhost ~]# route -n 
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eno16777736
    172.25.252.129  192.168.44.2    255.255.255.255 UGH   0      0        0 eno16777736
    192.168.44.0    0.0.0.0         255.255.255.0   U     0      0        0 eno16777736
    
    [root@localhost ~]# traceroute -I 172.25.252.129
    traceroute to 172.25.252.129 (172.25.252.129), 30 hops max, 60 byte packets
     1  192.168.44.2 (192.168.44.2)  0.185 ms  0.221 ms  0.074 ms
     2  * * *    -------------------
     3  172.25.252.129 (172.25.252.129)  5.753 ms  13.348 ms  13.770 ms
    

    When I add static route for next hop (

    172.27.226.254
    ), all is ok, but I can not add all next hops...

    [root@localhost ~]# route -n 
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eno16777736
    172.25.252.129  192.168.44.2    255.255.255.255 UGH   0      0        0 eno16777736
    172.27.226.254  192.168.44.2    255.255.255.255 UGH   0      0        0 eno16777736    -------------------
    192.168.44.0    0.0.0.0         255.255.255.0   U     0      0        0 eno16777736
    
    [root@localhost ~]# traceroute -I 172.25.252.129
    traceroute to 172.25.252.129 (172.25.252.129), 30 hops max, 60 byte packets
     1  192.168.44.2 (192.168.44.2)  0.143 ms  0.102 ms  0.065 ms
     2  172.27.226.254 (172.27.226.254)  7.625 ms  8.337 ms  8.306 ms                 -------------------
     3  172.25.252.129 (172.25.252.129)  8.275 ms  8.258 ms  8.228 ms
    

    Then, If I have multiple networks and I can only set one default route, so I must use static routes for other networks, but I can not trace all paths on these networks unless adding all next hops. How can I resolve this issue? Are there any alternative ways?

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