ForCES Forwarding Element Functional Model Lily Yang, Joel Halpern, Ram Gopal, Ram Dantu

Overview FE Model Open Issues & Next Steps

Motivation CE FE capability: what FE can be FE state: what FE is now FE configuration: what FE should be FE FE Functional Model

FE Block FE Block = Abstract Base Class for FE logical functions An FE block specifies: –Block ID or name (functional type) –Textual description of the function Need a namespace: –Extensible (to allow new functions later)

Block Library Requirements to support 8 categories of FE functions: –Forwarding –QoS –Filtering –Port –Security –High touch –Off-loaded –Vendor specific

FE stage & Directed Graph FE Stage: an instance of an FE block in a data path –Stage id (unique within the FE) –Block Name or ID –Number of downstream stages –List of downstream stage Ids FE Directed Graph: –Interconnection of the FE stages –Can support logical loops by configuring FE Block(s)

Issues List – FE/CE Topology control FE graph –Topology discovery should be out of scope (during initial stage of design) –No restriction of FE Block layout Smart CE should be able to figure out and allow/disallow functions. (Current draft addresses this) –Control of Topology FE has full control, less flexibility CE has full control, flexibility, but FE may not like all possible configuration on graph elements Balance approach will be better –Provide bunch of handles and don’t represent topology Most of the interconnection are hard wired

Issue List – Topology vs. Configuration (1) Graph representation –CE get bigger picture and important for behavior of NE It’s a constrained graph (pointers to existing work) –Difficulty in representation CE don’t have capability for any network, any FE, any protocol Logical loops and physical Loops representation CE interpreting any graph is complicated Element configuration –Focus on configuration and control Converting FE’s Topology to represent NE

Issue List – Topology vs. Configuration (2) Resolution –Complete dynamic is out of scope. –Semi-dynamic - Configurablity by manipulating properties of FE Blocks(s) (eg., QoS, IPsec, L5 switching ) –Describe list of function blocks for the model

TO DO List –Data modeling language: representation Candidates : SMI/SPPI/ASN.1/XML/UML Describe list of function blocks for the model WG Document?

Questions