Cell Relay Archive

[Thomas Frieling <thomas.frieling@experteach.de>]

In article <8j6l7e$jcg$1@nnrp1.deja.com>,
  zsquad@my-deja.com wrote:
> HI.
>
> Can someone explain the usage of AIS and RDI in an ATM environment.
>
> On a oc3 port there is an RDI light, does that indicate a problem is
> being reported from the router all the way at the other end of  the atm
> line?  or is it from an intermediate switch, and what does this mean.
>
> (...)

Hi,

the RDI-light normally says that there is a SDH/SONET failure - layer 1.
It occurs when only the receiver fiber is connected properly. An ATM-
switch can be configured to generate special "OAM"-cells that carry the
information of an occurred AIS or RDI along the ATM-connection.
Assume an ATM-connection going across six ATM-switches between two
Routers. If now somewhere between the 3rd and the 4th switch a SONET-
error occurs (due to a defective interface, a broken line or whatever)
the ATM-switches adjacent to the damage receive nothing or a SONET AIS/
RDI and generate OAM-cells of type AIS (upstream SONET-error information
is carried downstream the ATM-connection) or RDI (reverse). Upon the
reception of an AIS-cell the end station (here your routers) will
transmit an OAM-cell of type RDI on the same connection. The OAM-cells
appear in the statics menus of the end stations.
There are some specific configuration options about the OAM fault
management but I hope this helps.

Thomas Frieling

(These are all my opinions and they do not necessarily math those of my
employer.)


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