US 7,480,292 B2Granted

Methods of processing data packets at layer three level in a telecommunication equipment

AssigneeAlcatel

InventorsItalo Busi, Pietro Vittorio Grandi, Michele Fontana, Giovanni Zangrando

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Abstract

Method of processing MPLS packets in a telecommunication equipment comprising the following steps in the following order: incoming direction: count received frames and octets, validate packets, determine interface identification, count received packets and octets, strip external header, lookup for destination of incoming packets, next layer decision and forwarding, TTL management, if next-hop is not the equipment, PHB determination; outgoing direction: extract TTL from received outgoing client packets, forward received outgoing client packet as stripped MPLS packet with FEC, PHB, TTL, generate End_of_Stack bit, forward stripped MPLS packet with FEC, PHB, TTL, End_of_Stack lookup for destination of outgoing client packets with FEC originated by the equipment, TTL management create MPLS header, count transmitted packets and octets, forward MPLS packet, PHB, Next Hop.

Claims11

Dependent claims

A method of processing IP packets at layer three level in a telecommunication equipment, the equipment comprising a first box containing layer 4 protocols, and a second box containing hardware interfaces and layer 2 drivers, the method comprising the following steps in the following order, which are performed by a first termination block:

in the incoming direction:
validating IP packets by performing checks,
managing options field by interpreting all the options that said first termination block understands and preserving unaltered all other options,
filtering,
deciding first next layer and forwarding;
in the outgoing direction:
managing redirect by checking if the packet that is going to be sent satisfies the following conditions:
the IP packet has been received from a same interface over which the IP packet is going out,
the source address belongs to a sub-network of a next-hop,
there is no source route option,
managing TTL by considering a valid packet any IP packet addressed to the equipment and with TTL equal to zero,
managing source address,
managing options field by interpreting all the options that said first termination block understands and preserving unaltered all other options,
fragmenting packets when the packet to be routed has a size greater than a Maximum Transmission Unit,
wherein, in case of IP packets originated from or destined to the equipment, said method further comprising the following steps in the following order, which are performed by a second termination block in the incoming direction, after the first next layer decision and forwarding step:
validating the IP packets by performing checks,
reassembling incoming fragmented packets,
managing options field by interpreting all options that said second termination block understands,
deciding second next layer by stripping the header and forwarding the payload to the upper client layers using the protocol as selector;
in the outgoing direction, before the step of managing redirect:
multiplexing IP payloads coming from different upper layer protocols,
managing options field, and
generating IP headers.

20 more elements

Method of processing MPLS packets at layer three level in a telecommunication equipment, the equipment comprising a first box containing layer 4 protocols, and a second box containing hardware interfaces and layer 2 drivers, the method comprising the following steps in the following order, which are performed by a MPLS box:

in the incoming direction:
counting received frames and number of octets through an incoming termination block of said MPLS box,
validating MPLS packets against label range through said incoming termination block,
determining an interface identification through said incoming termination block,
counting received packets and number of octets through a first incoming adaptation block of said MPLS box,
stripping an external MPLS header retrieving stripped information through said first incoming adaptation block,
looking up for a destination of an incoming MPLS packet through a connection block of said MPLS box,
deciding next layer based at least on End_of_Stack flag through a termination block of said MPLS box,
forwarding to the next layer through said termination block,
managing TTL through a second incoming adaptation block and through an adaptation block of said MPLS box,
if next-hop is not the equipment itself, determining PHB through said second incoming adaptation block and through said adaptation block;
in the outgoing direction:
extracting TTL from a received outgoing client packet through said adaptation block,
passing on the received outgoing client packet as a stripped MPLS packet together with FEC, PHB, TTL through said adaptation block,
generating an End_of_Stack bit through said termination block,
passing on the stripped MPLS packet together with FEC, PHB, TTL and End_of_Stack through said termination block,
looking up for the destination of outgoing client packets with FEC originated by the equipment through said connection block,
managing TTL through an outgoing adaptation block of said MPLS box;
creating a new MPLS header and setting EXP bits according to said PHB through said outgoing adaptation block,
counting transmitted packets and number of octets through said outgoing adaptation block,
performing MPLS fragmentation and passing on MPLS packet, PHB, and Next Hop through an outgoing termination block of said MPLS box.

18 more elements

Dependencies are inferred from the claim text.