topic why route work ircoorrectly? in Operating System - HP-UX

why route work ircoorrectly?

faust2004 — Tue, 30 Apr 2002 01:55:29 GMT

Hi, export,
In my sun box (sloaris 2.7), netstat -rn show:
Routing Table: IPv4
Destination Gateway Flags Ref Use Interface
-------------------- -------------------- ----- ----- ------ ---------
10.17.65.0 10.17.65.25 U 1 4080 hme0
224.0.0.0 10.17.65.25 U 1 0 hme0
default 10.17.65.1 UG 1 55096
127.0.0.1 127.0.0.1 UH 312341988 lo0

but traceroute 132.97.64.6 show :
1 10.17.65.220 1.494 ms 0.917 ms 0.831 ms
2 **
why It does not route through default route 10.17.65.1 but 10.17.65.220(a pc, not router)?

Thanks
Sunny

Re: why route work ircoorrectly?

Steven Sim Kok Leong — Tue, 30 Apr 2002 02:03:03 GMT

Hi,

Can you show your ifconfig settings? What is the netmask set for your interface?

# ifconfig hme0

Hope this helps. Regards.

Steven Sim Kok Leong

Re: why route work ircoorrectly?

faust2004 — Tue, 30 Apr 2002 02:45:44 GMT

ifconfig -a
lo0: flags=1000849 mtu 8232 index 1
inet 127.0.0.1 netmask ff000000
hme0: flags=1000843 mtu 1500 index 2
inet 10.17.65.25 netmask ffffff00 broadcast 10.17.65.255
ether 8:0:20:90:ce:e5

Re: why route work ircoorrectly?

sven verhaegen — Tue, 30 Apr 2002 06:05:42 GMT

is this PC some sort of firewall ??? could be the router is redirecting you to that point

Re: why route work ircoorrectly?

sven verhaegen — Tue, 30 Apr 2002 06:25:50 GMT

i've been looking a little deeper in this one ,if the router doesn't redirect the packet this would need an error in the mask in your routing table to react like this :
if your netmask is indeed correct it is 255.255.255.0 meaning it should standardly go to the default gateway , however if for one reason or another the entry in the routing table would be 'wrong' that is not have the subnetmask not set to 255.255.255 but to 255.0.0.0 which is standard A class this could also explain the behaviour , it will then just flush the request(packet) on your local lan and any router capable device that can forward it will do so , if the PC is faster then the router to receive it , it would forward and the reply would conatin it's address (e.g. this implies a 'fault' in the routing table)

Re: why route work ircoorrectly?

Ron Kinner — Tue, 30 Apr 2002 18:55:17 GMT

Can you ping your router?

Run a traceroute to the ip address of another interface on the router and see what happens. There would be no reason for the router to redirect that kind of traffic.

Check the route tables and masks on your router. Odds are it thinks the best route to the destination is via the PC and is doing a redirect.

Also if a Cisco router make sure it has "ip classless" on.
Come to think of it I bet this is the problem. The router is probably running pre 12.x code which has no ip classless by default and it has a default route over a serial link to another router which has some 10 net addresses but they are not listed individually in its routing table so it assumes that the 10.17.65.x LAN is the best way to go to get to other 10 net addresses. Turn on ip classless and it should stop messing with your mind.

Ron