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Hello,
Strange behavior observed - and I am not sure, but it seems to be
Cisco related..
Got router 1750, on one of the interface I have Cisco switch
(1900) connected; to the switch there are connected: hp notebook,
and rs/6000 server (aix machine). Both of them have IPs from same
subnet (192.168.0.0/255.255.255.0).
Behavior I mentioned is:
- I am telneting to the router
- From the router I may ping notebook (always) and aix (but only
from time to time)
- If I may ping aix from the router, I may also telnet to this
machine; If I may not I have to.. ping aix machine from the
notebook, and after that I may ping/telnet to the aix machine from
the router as well.
To summarize - I may always ping/telnet to the aix machine from the
notebook, but not always from the router; If I cannot ping/telnet
to the aix machine from the router, I have to ping/telnet to the
aix from the notebook, and after that (no matter if I stay connected
or not) I will be able - during short time - ping/telnet to the aix
machine also from the router.. few minutes later aix is 'blocked'
again, and all the show needs to be started from the beginning
Can anybody help? To answer first auestion yes, I have tested
other ethernet cable, yes, I have checked other switch port, and
no, it made no difference My config is below. Thanks for any
suggestion.
regards
Tomasz

-------

cisco#sh runn
Building configuration...

Current configuration : 1540 bytes
!
version 12.3
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname cisco
!
boot-start-marker
boot-end-marker
!
logging buffered 8129 debugging
enable secret 5 $1$WrSd$rtdJ007MsUbHAM762laAE/
enable password xxx
!
memory-size iomem 25
no aaa new-model
ip subnet-zero
!
!
!
ip dhcp pool local
network 192.168.0.0 255.255.255.128
domain-name xxx.xxx
dns-server 213.46.172.36
default-router 192.168.0.1
lease 7
!
ip dhcp pool aix
host 192.168.0.10 255.255.255.0
client-identifier 0108.005a.93b5.06
dns-server 213.46.172.36
default-router 192.168.0.1
lease 7
!
!
no ip domain lookup
ip cef
no scripting tcl init
no scripting tcl encdir
!
!
!
!
interface Ethernet0
mac-address 0014.3815.4170
ip address dhcp
ip nat outside
half-duplex
!
interface FastEthernet0
description connected to EthernetLAN
ip address 192.168.0.1 255.255.255.0
ip nat inside
speed auto
half-duplex
!
interface Serial0
no ip address
shutdown
no cdp enable
!
ip nat inside source list 1 interface Ethernet0 overload
ip nat inside source static tcp 192.168.0.10 23 interface Ethernet0 32
ip nat inside source static tcp 192.168.0.251 80 interface Ethernet0 52
ip classless
no ip http server
!
!
no logging trap
access-list 1 permit 192.168.0.0 0.0.0.255
snmp-server community public RO
snmp-server enable traps tty
!
control-plane
!
!
line con 0
exec-timeout 0 0
password xxx
login
line aux 0
line vty 0 4
exec-timeout 0 0
password xxx
login
!
!
end

cisco#

----

where 192.168.0.10 is aix IP, 192.168.0.251 is catalyst 1900 IP.

once more regards
Tomasz

wrote:
> ip dhcp pool local
> network 192.168.0.0 255.255.255.128
^^^

> ip dhcp pool aix
> host 192.168.0.10 255.255.255.0

> interface Ethernet0
> mac-address 0014.3815.4170
> ip address dhcp
> ip nat outside
> half-duplex
> !
> interface FastEthernet0
> description connected to EthernetLAN
> ip address 192.168.0.1 255.255.255.0
^^^


> where 192.168.0.10 is aix IP, 192.168.0.251 is catalyst 1900 IP.

Netmasks need to agree for all devices in a single
subnet.
The occasional operation is due to ARP snooping.
One of the devices is unable to ARP for
the target host but the other is,
My guess is that the mask on the cat 1900
could be 255.255.255.128.
During this correct ARP exchange the
target snoops the activity and puts the
discovered entry in its table.

On cisco "show arp"
On Unix and windows usually "arp -a"