Upenn TCOM program will certainly provide good prospects. Upenn is very reputed and offer some great courses in the field of networking.
RA positions are very competitive and are offered to students who have shown research interest and intellectual capabilities. Its usually hard to get TA in first semester. However if you perform well in your courses you have chance for being TA of that subject. Upenn provides no funding even if you get TA/RA.
Regarding placements- well lot of financial/consulting companies visit Upenn and TCOM students are placed there for technical roles. However very few technical and core networking companies come on campus. So you have to apply off campus. If you want better on campus job opportunities in pure technical firms then you should probably consider west coast.
Please join Upenn rangoli group and Upenn TCOM group where you will find lot of discussions. I hope this helps. Feel free to shoot an email if you have any query.