Error message from yum update on RedHat 7.2 syatem

[Nachiketa Sadhu <sadhu idc iitb ac in>]

Hi,

I installed yum on a RedHat 7.2 system as explained in "Using 
Fedora Legacy's yum for Red Hat Linux 7.x" documentation. On 
giving the command to update, I am getting the following error 
message:
[root abhikalpa root]# yum update
Gathering package information from servers
Getting headers from: Red Hat Linux 7.2 base
Error getting file 
http://download.fedoralegacy.org/redhat/7.2/os/i386/headers/header.info
[Errno 4] IOError: [Errno socket error] nonnumeric port

I am behind a proxy server, and use a HTTP_PROXY setting.

Can any one suggest any solution?

Thanks

sadhu