Do you know if I have a 2800 series and a 3800 series router, do you know what is the maximum number of T1 serial interface I can bundle together to form one logical multilink Port?
I usually have 4xT1 (6Mbps) and done via two vwic2-2MFT-T1/E1 interface cards. But I wonder if it is okay to do 8xT1 or even more to form a single logical Port?
Here is a relatively recent document (Updated: Jan 29, 2008) that suggests the use of 8 T1/E1 is possible at least in high end products, and warns about CPU usage even in this case:
The above document refers to a white paper:
Table 1 in this white paper suggests that you can expect use of MLPPP with any serial PA (probably because, as this same table says, MLPPP is a software only solution) and you can have 2-8 T1/E1's per bundle in general.
Still, to be on the safe side, you might consider asking cisco about this as Joseph suggested.