Moby Dick Consolidated System Integration Plan

D0103v1.doc Version 1 6.7.2003
4.2.3.2 Interface between QoSManager and DiffServ Logic
PEP communicates with DiffServ Logic using an API: The IBM TC API. This section describes shortly
the main functions of the API.
• First is the call of the API function QSession() which creates a netlink socket to communicate
between the kernel space (where DiffServ Logic runs) and the user space (where PEP code
runs).
• To configure queues in the DiffServ Logic a two step process is followed. We first call the API
function AddQDiscCBQ() is first called to reserve and configure some resources of a router
interface for later creating the queues in those reserved resources. Then, for each queue we want
to create in the mentioned interface, we call AddTClassCBQ(). If we want to create queues other
than CBQ we may also call AddQDiscName() and AddTClassName().
• To create filters to route packets to any of the queues created in the preceding step, we have to
call two API functions. First we create a set of conditions the packet must meet using the
function AddCondition() as many times as needed. Then, we aggregate these conditions and
create the filter using AddFilterU32Filter(), this functions allow us to specify to which queue the
packets meeting the above created conditions will be routed.
DiffServ Logic has also to tell the PEP when a packet that does not match any filter rules arrives, so that
the PEP initiates the Authorization Process. But TC does not allow that. So we use pcap. Pcap captures all
the packets and stores in a shared memory variable packets parameters (CoA and DSCP). PEP checks this
shared memory variable and looks if any (CoA, DSCP) pair is not in his DSCP table. In that case it begins
the authorization process begins.
A wrapper around IBM’s TC API has been designed. Its more relevant functions are:
Create_session(interface)
Create_initial_qdiscs()
create_CBQ_class(BW, borrow_bw)
create_GRED_VQ(queue capacity (min, max) discard probabilty)
create_default_filter(class to send packets matching none of the filters)
add_filter6(CoA, DSCP, class to send packets matching this filter)
tell_stats(interface_status)
4.2.3.2.1 Flow sequence between PEP and DiffServ Logic
No. Function call Remarks
1 Create_session
To initiate DiffServ Logic
2 Create_initial_qdiscs
3 create_CBQ_class As many times as needed
4 create_CBQ_class
As many times as needed
5 create_GRED_VQ
6 create_CBQ_class
CBQ can be created and deleted as
needed
7 delete_CBQ_class
create_default_filter
8 add_filter6 As many times as needed
9 add_filter6
10 remove_filter6
11 Stats As many times as needed
Table 14: Flow Sequence between PEP and DiffServ logic
Filters can be created and deleted as
needed
4.2.3.3 Interface between the QoSManager and the Integrated Logger
Each time the Access Router is going to send a ‘Resource allocation Request’ message asking
authorization for an active traffic not installed at this time, the router is forced to log this event for later
auditing. After the response is received and the report state message sent, this event must also be logged.
The Integrated Logger functionalities are provided by the API ‘SessionSetupLogger’.
The interface provided by the Integrated Logger is simple and consists of three functions and a structure.
The functions are:
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