Cell Relay Archive

[Paul Koning <pkoning@xedia.com>]

tony_ducks@my-deja.com wrote:
> 
> I have an additional query about VPC and VCC operation, regarding the
> use of OAM alarm flows.  F4 flow operates at VP level and F5 flow at VC
> level.  Is F4 provided on VCCs or only on VPCs?  Ditto, does a VPC
> connection support F5 flow, or is that the reponsibility of the end
> equipment which is provisioning the VC value?
> Does network access equipment forward F4 flow to terminal equipment, or
> just F5 as that is the VCC?
> So, if you are monitoring a network could you tell which cellstreams
> were part of VPC and which are VCC by examining what type of OAM F4/F5
> flow was present?

Let me make a stab at this... 

F4 flow lives in a well-defined VCI within the VPC.  F5 flow is a
payload type in the VCC.  So yes, you can tell with a cell monitor
which is which.  F4 by definition exists only in a VPC, since it is
recognized by its unique VCI which cannot exist as a piece of a VCC
(which has its own, different, VCI).

A VPC supports F5 flow in a sense, because it carries VCCs, which
in turn carry F5 flows.  But the provider of the VPC has no awareness
of the F5 flow.

An end to end flow goes to the end of whatever it's flowing in :-)
So if a network provides VCC service but uses VPCs internally, the
F4 flows terminate where the VPC stops.  On the other hand, if
you have VPC service all the way to the customer, then the customer
terminates the end-to-end F4 flow and the network just forwards those
cells just like any ordinary data cells.

	paul

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