RHEL or VMWare ESX or HP Gbe2c switch problem?

[sunhux G]

I would like to just zoom into my specific problem here :

We have a HP Proliant 480C blade that comes with a HP Gbe2c Layer3
switch built in (ie you can't see the NIC of the blade server, only switch
ports).
It's VMWare ESX & we have just built one Windows client in it & now we
have just installed a second guest client (a noncluster RHEL Ver 5.2) :

a)we have succeeded in building a Windows guest client  inside this VMWare
   ESX earlier.  The Windows client has an  IP addr 10.51.x.y  &  it uses
the
   very same switch & is able to get connected to other LANs.  From this
   Windows client, I'm able to ping to other external servers on other
subnets
   & vice-versa.  The Layer 3 switch could ping to the Windows client too

b)We just installed Redhat Linux 5.2 inside the same VMWare, it's able to
   to boot up fine, just that it's unable to even reach the built-in Layer 3
switch:
   From this Layer3 switch, I'm able to ping to the Windows guest client
   10.51.x.y  but  from this built-in Layer3 switch, I'm unable to ping to
the
   Linux client  (with vswif0 interface addr 172.17.y.z up & running)

c) I then tried to configure an IP addr for eth2 (172.17.y.t) in this Linux
    client,  restart network (shown as Ok for both vswif0 & eth2 during
    "/etc/init.d/network restart"  but it did not help make (still
unreachable)

What's the problem here?

The switch has one default VLAN1 in it - must I specify "tagging" during
the Linux installation to this VLAN1  or I'll need to create another VLAN
in the HP built-in switch or  ...... ?

Is there a firewall within Linux which could have prevented these
connectivity
& if so how do we disable it?

Any ideas/brainstorming suggestions appreciated



Thanks
U