routing and arp problem

[Juergen Tappe]

Hi,
in one of our subnets any HP-UX system has a problem to reach any system outsite this subnet.

i.e. a traceroute -n www.google.com returns:
traceroute to www.google.akadns.net (66.102.11.104), 30 hops max, 20 byte packet
s
1 10.99.4.84 1 ms !N 0 ms !N 0 ms !N

and no ping or whatever to anywhere except the local subnet.

Lansettings of one of these systems as an example:
#ifconfig lan0
lan0: flags=843
inet 10.99.4.84 netmask fffffc00 broadcast 10.99.7.255

Please note the special subnet mask.

#netstat -rnv
Routing tables
Dest/Netmask Gateway Flags Refs Use Interface Pmtu
127.0.0.1/255.255.255.255
127.0.0.1 UH 0 174392 lo0 4136
10.99.4.84/255.255.255.255
10.99.4.84 UH 0 98539 lan0 4136
10.99.4.0/255.255.252.0 10.99.4.84 U 2 0 lan0 1500
127.0.0.0/255.0.0.0 127.0.0.1 U 0 0 lo0 4136
default/0.0.0.0 10.99.4.255 UG 0 0 lan0 1500

if I do :
route delete default 10.99.4.255
route add default 10.99.4.255 1

ping/traceroute is OK for about a minute.
After that I have the same problem.

The 10.99.4.255 IP is one of several Cluster IPs of another HP-UX System, which connects to other subnets.

with a fresh initialies default route arp shows me :
#arp -a | grep 8:0:9:c3:ca:92
system1.xx.de (10.2.4.1) at 8:0:9:c3:ca:92 ether
system2.xx.de (10.2.4.121) at 8:0:9:c3:ca:92 ether
system3.xx.de (10.2.4.255) at 8:0:9:c3:ca:92 ether
(system names changed)

as soon the ping hangs, the .255 entry ismissing in arp.

I have the problem on all HP-UX systems in this subnet with various models lan card types.
But no other computer running i.e. windows/linux/sun has any problem with the default .255 router.

I guess this is something HP-UX specific together with the combibation of special subnetting, the .255 IP for the router and the multilpe IPs for the same MAC (arp).

But how I make it running ?
What else I can check / configure ?

Any ideas?
Thx in advance
Juergen

[RAC_1]

ndd -h ip_ire_gw_probe

Get the setting.
ndd -get /dev/tcp ip_ir_gw_probe

Set it to 0

ndd -set /dev/tcp ip_ire_gw_probe 0

Hardcore the settings in /etc/rc.config.d/nddconf.

Anil

[Sanjay_6]

Hi Juergen,

"0" and "255" in the last field of an ip address are not allowed.

http://www1.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000007950522

For eg,

//Quote//

CLASS C ADDRESS:
NETWORK PORTION range is 192.0.1 - 223.255.254
number of available hosts is 254
24 NETWORK bits; 8 HOST bits

//EndQuote//

You'll see the no of available hosts is 254 (0-255=256 addresses, These two excluded are 0 & 255)

Hope this helps.

Regds

[Juergen Tappe]

RAC,
Thx very much.
The commands are working perfectly and my test ping is running > 30 mins now.

But :
When I configure /etc/rc.config.d/nddconf
to :
TRANSPORT_NAME[5]=ip
NDD_NAME[5]=ip_ire_gw_probe
NDD_VALUE[5]=0

and execute ndd -c
The value keeps on "1".
Im doing something wrong? what?

Sanjay:
It is possible using special subnetting, which we are doing since years.
Cut+paste out of "your document"
CLASS B ADDRESS: 16 NETWORK BITS 16 HOST BITS

# BITS NETMASK # SUBNETS # HOSTS
(contiguous) PER SUBNET

2 255.255.192.0 2 16382
3 255.255.224.0 6 8190
4 255.255.240.0 14 4090
5 255.255.248.0 30 2046
6 255.255.252.0 62 1022 <- We are using this one
7 255.255.254.0 126 510
8 255.255.255.0 254 254
9 255.255.255.128 510 126
10 255.255.255.192 1022 62
11 255.255.255.224 2046 30
12 255.255.255.240 4094 14
13 255.255.255.248 8190 6
14 255.255.255.252 16382 2

[Juergen Tappe]

Anybody knows how to configure /etc/rc.config.d/nddconf correctly or which command to use to enable the entries in it?

ndd -c ist nor working.

[James A. Donovan · Accepted solution]

The standard nddconf file has many examples of what parameters you could set. These examples "use" indexes 0,1,2,3 and 4.

I notice you used index [5] to set your parameter. Do you have 5 other uncommented values being set? If not, then you should be using index [0] (or whatever is appropriate...)

e.g.

TRANSPORT_NAME[0]=ip
NDD_NAME[0]=ip_ire_gw_probe
NDD_VALUE[0]=0


# For each additional tunable parameter, add a set of variable assignments
# like the ones below, changing the index to "[0]", "[1]" et cetera.
# Index must be starting from 0 and they must be in sequential order.
# Missing index values inside the array range is not supported.

[Juergen Tappe]

Again, thats what I entered to nddconf :

TRANSPORT_NAME[5]=ip
NDD_NAME[5]=ip_ire_gw_probe
NDD_VALUE[5]=0

but when I execute "ndd -c" or "ndd -a" the value keeps on 1.
N.B. /sbin/init.d/net or .../net.init using these ndd commands.
So: I assumed these are changing what I configured, but thats not the case.

[Juergen Tappe]

I didnt wanted to use the [0] because there are these examples, and if somebody uncomments one of them i.e. the [0] the new change will not be active anymore.

I will try to use [0] tomorrow......

thanks for the tip.

[James A. Donovan]

Look closely at what you've written, and what I've written.

I wrote:

TRANSPORT_NAME[0]=ip
NDD_NAME[0]=ip_ire_gw_probe
NDD_VALUE[0]=0

You wrote:

TRANSPORT_NAME[5]=ip
NDD_NAME[5]=ip_ire_gw_probe
NDD_VALUE[5]=0

The index values are different. If you are not setting any other parameters in your nddconf file then you MUST use index 0.

[Juergen Tappe]

Jim,

you are absolutly correct, with index [0] its working fine.

I realy should have read the nddconf file and your post more carefully.

Sorry and Thx