[Ilugc] Can not ping via switch consistently

[Arun Khan]

2010/10/6 ராஜ பாண்டி <vrpcse at gmail.com>:
>
>  I am having a switch ,one server and 3 systems which are connected to
> the switch. The IPs are 192.168.48.9, 108,109,110 respectively.
> Netmask is 255.255.240.0 .

I am presuming the "server" is 192.168.48.9 since you have not
explicitly stated so.  What is your objective for using a /28 netmask?

Anyway, with a /28 netmask, the "server" is on a different subnet
vis-a-vis your other systems.  see [1] and [2]

> Now there is no problem in ping command
> among 108,109,110 always. But i can ping the server from only one
> system either 108 or 109 or 110.

Given you are using a /28 netmask this is interesting ... even though
the 2 subnets are on the same physical fabric, you would need some
kind of routing to occur for ping to work between hosts on the 2
subnets.

>  If 192.168.48.109 pings the server,
> 108,110 did not ping the server. After some interval 192.168.48.110
> pings and 192.168.48.109,108 did not ping the server. I also checked
> the cables. They are all right. What is the problem in network
> connection? Can someone bring me out?

IMO, the netmask is your problem.  With a  /24 netmask all the
machines should be able to ping each other.  (make sure iptables and
SE Linux are disabled)

Buy a new switch if the problem still persists.

[1]  $ sipcalc 192.168.48.9 255.255.255.240
-[ipv4 : 192.168.48.9 255.255.255.240] - 0

[CIDR]
Host address		- 192.168.48.9
Host address (decimal)	- 3232247817
Host address (hex)	- C0A83009
Network address		- 192.168.48.0
Network mask		- 255.255.255.240
Network mask (bits)	- 28
Network mask (hex)	- FFFFFFF0
Broadcast address	- 192.168.48.15
Cisco wildcard		- 0.0.0.15
Addresses in network	- 16
Network range		- 192.168.48.0 - 192.168.48.15
Usable range		- 192.168.48.1 - 192.168.48.14

[2] $ sipcalc 192.168.48.108 255.255.255.240
-[ipv4 : 192.168.48.108 255.255.255.240] - 0

[CIDR]
Host address        - 192.168.48.108
Host address (decimal)    - 3232247916
Host address (hex)    - C0A8306C
Network address        - 192.168.48.96
Network mask        - 255.255.255.240
Network mask (bits)    - 28
Network mask (hex)    - FFFFFFF0
Broadcast address    - 192.168.48.111
Cisco wildcard        - 0.0.0.15
Addresses in network    - 16
Network range        - 192.168.48.96 - 192.168.48.111
Usable range        - 192.168.48.97 - 192.168.48.110

-- Arun Khan