[c-nsp] Monitoring L3 link status

[Frank Bulk]

We're using two Cisco 3750-ME routers (B & C) that are connected to our
upstream service provider's routers (D & E).  We started using ping checks
to D & E from our server running SolarWinds, but because our internet
traffic runs primarily over B-D or C-E it's not really a good link test.  If
our traffic runs over C-E then ping checks to D run over C, E, and then on
to D.  Link B-D could fail and we wouldn't know.

           |---OSPF---[B]---BGP---[W]---[EoS]---[EoS]---[D]
           |           |                     / \         |
server ----A         OSPF                   |   |       BGP
           |           |                     \ /         |
           |---OSPF---[C]---BGP---[X]---[EoS]---[EoS]---[E]

This can't be a new issue -- what's the easiest way to test L3 connectivity
between B-D and C-E?  All our connections internally and to our upstream
provider are Ethernet, transport is Ethernet over SONET) and testing for
interface status is not reliable enough as our demarc with our upstream
provider is a Cisco 2950 (W & X).  I believe our upstream provider uses
Juniper routers.

Regards,

Frank