We currently have a single 1.5mb connection to the frame cloud and management has decided to add another in hopes of 'bonding' the connection to the cloud to 3mb. I don't think bonding in that sense is possible from our 3640. What are some options?
Hmmm... I suppose you could pp over it, and use mlppp.... Well, nevermind. :-) You should be able to get fairly resonable load sharing over two links like this using cef's load sharing techniques. You can always use per packet, at the risk of out of order packets, and get pretty close to the best load sharing you're going to get, statistically.
As long as the lines have close enough delay that you don't get out of order packets, then it shouldn't matter that you are running voip on it. Of course, you're going to get better packet ordering with per source/destination load sharing, and in terms of efficiency, it's often better to have some unequal use on the links and have in order packets.
Are you running full route BGP? if you do, it'll be pretty tough to do this. You may running out of memory on the 3640 which has max. of 128MB. You do have some options: ask the ISP to send only the summary routes, or change the router to 7200 class. You may check the current free memory of the router. If you are running static route with ISP, I don't see any problems for adding another T1 frame links to the 3640 router.
You can bond 2 T1s if you have an NM-4T (4 port synch) on your router and use a CSU/DSU that can multiplex multiple T1s. A Datalink 3800 will bond up to 8 T1s. The NM-4T allows you to use 1 port at 8Mbps or 2 port each at 4Mbps.
If you are going for speed, then go with inversed mux option - meaning "bonding" multiple T1 as a single link. The serial port on your 3640 could support multiple T1 speed (don't remember the max, but 2-3 T1 is safe). With this option, there is less over head over balancing/queing method, but you'll need a multiplexer for this, however.
While its not a redundant in design design, the InversedMux option does offer redundancy. If one link fails, it will not affect the connectivity - just the speed. But this redundancy fails if local loop fails and both of your circuit is in same carrier switch. If you need a full redundancy, then you'll need a different design. Good luck.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...