welcome to the forum
Please give a description what you want to achieve instead of repeating the subject.
This makes possible to give you an answer.
I want to migrate my entire project which is written in EJB2.1 from Jboss 6 to Jboss 7. Accourding to my knowledge JBOSS 7 doesn't support custom JNDI name,that I have used earlier in jboss.xml.
Now if I want to migrate then I need to change lot of code for JNDI that means I need to update the JNDI names given by JBOSS7.
I want to know is there any way wherein I can use my existing JNDI names in JBOSS7.
Please ehlp me.
Thanks in advance.
Have a look to  for migration issues.
If it was me I would upgrade to EJB3 as it's easier to handle and you have still the migration effort. Also EJB2 is running out of interest, I suppose there is less support for enhancements.
To map your JNDI names you should have a look into the subsystem 'naming'. You can add a <bindings> section and add individual aliases
<lookup name="java:global/Alias" lookup="ejb:app/modul/......"/>