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Queuing management:
–
It provides to monitor the load of traffic in the local router, and to take measures for preventing the
congestions, supported by the intra–board microcontroller, such as: management of many different
queues and relative priorities, packets queuing, packets discarding, packets lifetime management,
etc. It implements, mainly, for this function, the following mechanisms:
•
256 queues for each "logical" port (the logical ports number is 63)
•
scheduling, by means of HOL or WC–WFQ or WNC–WFQ methods
•
congestion avoidance via W–RED method (Weighed–Random Early Discarding): in
occurrence of congestion conditions signals, a random packets discarding is started, in order
to prevent the traffic worsening.
•
The priority management is based on the ethernet SLA (Service Level Agreement), by means
of CIR and PIR values of the traffic contract.
•
Three types of QoS (Quality of Service) are available: Best Effort bandwidth (BE–BW), Min–BW
with regulated bursts, Guaranted constant BW.
•
A "Dual–Rate Leaky–Bucket" police mechanism is used (it can be seen as two cascaded leaky
buckets, the first based on PIR value, the second on CIR).
•
In case of congestion, only the low priority traffic will be cut–off, while the high priority traffic
maintains the guaranted BW.
•
The Best–Effort traffic deployed in ring topology can be associated to a "Fixed Share" of the total
available band, or to a "Variable&Proportional Share". In case of congestion the BE excess
traffic will be cut–off via W–RED.
•
Packets shorter than the minimum ethernet frame are silently discarded. Packets longer than
the maximum frame are silently discarded. The discarded packets are counted by the PM
function.
•
Note: the priority and the BW parameters are marked on the first label, at the "PUSH1" function
of the ingress node.
Microprocessor:
–
It is a local microcontroller managing and supporting the MPLS functionalities, such as:
The RSVP–TE and LDP communications between the destination and the origination nodes,
in order to establish the routing and the LSP tunnelling.
Management of communications with the EC and the network Operations System (OS), by
means of SNMP (Simple Network Management Protocol) messaging, for MPLS network
configuration.
Configuration of the MPLS functions implemented by the devices on the board, by means of
ICMP (Internet Control Message Protocol) messaging.
Collection of alarms and status of the MPLS functions.
Management of the Performance Monitoring (PM) function for MPLS.
Management of Multicast traffic.
Management of OSPF (Open Shortest Path First) routing (not operative).
Furthermore it aids the congestion control function, supporting the "Queuing Manager"
Communications with the EC, by means of the ISSB–EC bus, for software data transfer.
It is provided with relevant SDRAM and Flash EPROM devices, for data and software storage.
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