MT92210 Zarlink Semiconductor, MT92210 Datasheet - Page 49

• Manufacturer Part Number: MT92210
• Description: 1023 Channel Voice Over ip (VoIP) Processor
• Manufacturer: Zarlink Semiconductor

Data Sheet
6.0
Packets received from the network must go through a look-up process to determine what is their destination. The
first step in choosing a final destination for a packet is determining its packet type.
6.1
The two most important decisions are whether or not the received packet is an IP packet, and whether or not it is a
null-encapsulated packet. A null-encapsulated packet is a packet that is transported over AAL5 and whose IP and
UDP headers are eliminated to save bandwidth.
Regular IP packets must also be sub-classified: their IP version (v4 or v6) must be determined, and the protocol
used below IP is established. Non-fragmented UDP packets are grouped together in one category, while
fragmented packets or non-UDP packets are grouped separately.
IP packets with a version other than v4 or v6 are routed separately. Non-IP packets are also routed separately. And
lastly, three “special” headers can be decoded and used to take decisions on packets: these are the MPLS label,
the MPOA tag, and the LANEv2 ELAN-ID.
Table 13 lists all the packet types that MT92210 can identify. Each type has an associated Initial Search Structure,
which has a fixed location in SDRAM C. Any received packet must fall into one of the type, and will be handled as
per the instructions in Initial Search Structure. Packets that contain one or many of these headers may require
multiple look-up iterations before being assigned to their final destination
Packet Identification
Packet Types
Table (1
subnet)
logical
Flow
RX RTP Connection
Structure Base Address
per
IP Address
Index
(points to an
entry in the
Flow Table)
Post-Search
Process
connection or
Confirmation
Post-Search
Structure (1
header)
If the post-search process decides to search for the
packet in the binary tree using another profile
per
Structure (1 per
Profile Default
Post-Search
profile)
Match
No Match
Binary Tree
(global)
Binary Tree
Figure 24 - Packet Identification
Search
Zarlink Semiconductor Inc.
Memory Entry
Mask) (1 per
Profile)
(Hash Key
Profile
Identification
Key CRC +
hashing
Structure (1 per
Initial Search
packet type)
Identifi-
cation
Key (pre-
CRC)
If the initial search was for an MPLS label, MPOA
tag or ELAN ID, and the result is valid, then the
packet will be parsed again, ignoring that header
Memory
Header
(global)
Next
Parsing
Packet
(Option +
Memory
(global)
Profile
TOS)
Buffer Handles
(global)
Identification
Packet
MT92210
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