graphical tool to check bandwidth usage

[ESGLinux]

Hi all,
I have been asked for a graphical tool to check the the bandwith usage that
pass through my RHEL 5 firewall.

First I thought in the fantastic wireshark (a.k.a ethreal) but I don´t know
how to see in real time and in a graphical way the usage of the bandwidth
usage from the hosts from my local lan. This way I can see quickly if a host
is abusing.

I like wireshark but I need this feature, so, is there any way to get this
with wireshark?

If it´s not possible, it´s time to explore another solution, Do you know one
with gives me this possibility?

Thanks in advance

ESG