Unanswered Question
Jul 12th, 2007

Good afternoon, folks. I need to spec out a router to bond 3 T1s. Have any of you ran into any issues using a vwic2-2mft card in an MLPPP group with a wic-1DSU?



I have this problem too.
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jasonfaraone Fri, 07/13/2007 - 05:11

You shouldn't have any trouble with the second generation dual port VWIC's. The first generation had some timing issues, but nothing severe. If I recall, you need to set the second port's clock source to internal, even if your provider provides clock timing. As far as the single port cards with a 2mft, I've run in this configuration without issue.

shanemason Mon, 07/16/2007 - 05:46

You've ran one vwic2-2mft-t1/e1 and one wic-1dsu?

Thanks for the reply!!


jasonfaraone Mon, 07/16/2007 - 06:12

Well, I've run dual port and single port VWICs together, but for your purposes I dont think there is much difference. I typically run a quad T multilink at one of our sites, but while troubleshooting some line errors I swapped one of the T's to a single VWIC and didn't have any issues. Like I said, the majority of issues I have had with using dual port VWICs in a MLPPP bundle involved having both ports on the dual port VWIC set to clock source internal. IOS doesn't really seem to care where the T's come from, as your Multilink interface only deals with the logical serial interfaces.

Someone please correct me if I'm wrong, but that has been my experience dealing with this, and I manage a number of sites that use MLPPP.

pozurita Fri, 08/08/2008 - 07:58

I think I may be having the same issue, a MLPPP point to point bundle with two VWIC-2MTF-T1-DI (4 t1's) and one of the VWICS have errors (CRC, slips, etc) on both ports, I guess I should mention that a harware loopback test failed; dropped packets with 0x0000 and 0xabcd, 0x1111. I cant find any docs on if this is a known issue or what, at this point I am assuming I have a bad VWIC mod and replacing it. Any ideas?

ISP says it is not providing clocking, all 4 T1's same provider

bberry Thu, 08/21/2008 - 05:59

Can I ask what are you using as a standard hardware platform? We are looking into deploying a point-to-point to a remote locating using mlppp and I need to come up with the hardware to go on the ends. Will a 2811, 2821 work or do I need something a bit bigger? Will interfaces such as WIC-1DSU-T1-V2 work or do I need something different as well?



Richard Burts Thu, 08/21/2008 - 08:46


It is not clear in your post what kind of circuits and how many circuits you want to put into your multilink. I am pretty sure that either of the 2800s will do ok to multilink a couple of T1s. I have a customer running multilink for 4 T1s on a 2851 and doing very well. I do not see any reason why the WIC-1DSU-T1-V2 would have any problem in this.



bberry Thu, 08/21/2008 - 09:27

Sorry, guess I should have included that. At the moment the proposal is a 3Mb link using two individual T-1s. I am leaning toward at least the 2821s with either two WIC-1DSU-T1-V2 or VWIC2-1MFT-T1/E1.

Richard Burts Thu, 08/21/2008 - 10:04


The 2821 is a very nice router and it should certainly handle a pair of T1s multilinked. And it would leave you plenty of room to grow if they decide to add more links or to employ other features.



bberry Thu, 08/21/2008 - 10:20

That is my thought exactly. Will handle the d-dup nicely but still handle SAN replication if we ever move that far.



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