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T1 CSU/DSU V1 vs. V2

I've got a strange case where a t1 will not come up/up using a router that only supports the v1 T1 CSU/DSU.  The same circuit, same config comes up/up on a router with a V2 card. 

If it helps, the circuit is the customer-end of Sprint MPLS service with nothing special required beside the usual config to get the circuit up.  To be clear, the router only connects to the Sprint's MPLS service.  To be clear, my router doesn't need any MPLS config because Sprint is doing all the tagging/routing MPLS infrastructure.

I've set up a couple of t1's and partials before and never had this issue. 

Community Member

T1 CSU/DSU V1 vs. V2

Some more information:

Serial interface goes up/up on a 3250 router with a V2 T1 DSU/CSU and 12.4 firmware.  A V1 T1 DSU/CSU stays down/down

Serial interface is down/down on a 1921 with 15.1 and ipbasek9 firmware license.  The V1 T1 DSU/CSU is the only supported WIC for this device.

Community Member

T1 CSU/DSU V1 vs. V2

Greetings Jesus,

I don't mean to question your research into the compatability of your T1 interface, but a 1900 series router running Cisco IOS 15 seems to be a little new to not support a v2 WIC.  Maybe it was a misprint.  Maybe the 1900 supports V2, but not V1.  I was told the 1800 routers needed a V2 WIC, which would make it seem odd that a 1900 would only support a V1.  Have you tried the V2 interface in your 1921 router?

Would it be possible to share a show interface, with the ip address/subnet'd out?

Are there any hints in a "show controller" output?


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