I've been working for a small regional service provider for 3 years. 2 of the 3 years my work has been focused on the MPLS core and edge equipment. I just got around to getting my CCNA back in November of 2009 and now my employer would like me to get my CCIP within 6 months. I'm not sure yet how many resources the company is willing to put forth to help make this happen, but I would like to know if this even sounds realistic. If not, would the new CCNP path be any more realistic? I'm not going to pretend to be MIT material but I'm not a complete dolt either.
I can just underline Marias "it depends".
One of my former Coworkers did his in less than 4.5 Months. But I have to also say, he has a very good knowledge about the topics.
On top he was getting time to study, so he did not have to worry about his job.
Passed the Cisco Exam, then passed the Juniper 2 months later. Now he is working on some BlueCoat cert.
You see it "also depents" on your employers support.
As always, the answer to such questions boils down to the answer "it depends". From what you say, I tend to think the CCIP track would be more appropriate for you. Now, about the realistic timeline: does something like that even exist? I passed my BGP+MPLS on December 2008, QoS on January 2009 and CCIE SP written on January 2009 as well. Does this sound realistic? No! More than a year has passed and I haven't yet managed to sit for BSCI. Does this sound realistic? I guess the answer is 'no' as well! Besides experience and willingness to study, there are other factors as well you need to take into account (such as responsibilities in your personal life or having the time to eat some proper food every once in a while, it's good for the health ). I generally need some time to recover after passing a certification exam (say 2 weeks or more). Maybe 6-8 or 6-12 would be more realistic, but it still depends. Good luck!