MT92210 Datasheet, PDF (44/175 Pages) Zarlink Semiconductor Inc – 1023 Channel Voice Over IP Processor

Data Sheet
MT92210
LA [20] RA [20]
b31 b30 b29 b28 b27 b26 b25 b24 b23 b22 b21 b20 b19 b18 b17 b16 b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0
+0
Profile
Header CRC Key [55:32]
+4
Header CRC Key [31:0]
+8
Left Address [19:4]
Right Address [19:4]
+C
First Post-Search Confirmation Structure Address [24:7]
Figure 23 - Binary Tree Node
Field
Header CRC key
Profile
LA
RA
First Post-Search
Confirmation
Structure Address
Description
Bits 55:48 represent a CRC-8 of the initial identification key. Bits 47:32 represent a
CRC-16 of that same key, and bits 31:0 represent a CRC-32 of that same key.
Profile number being used to perform packet search. The profile number and header CRC
key, between them, represent the 60-bit identification key used to search for the packet.
Address of left node below the current node. The left node will contain an identification
key that is smaller than the current one.
Address of right node below the current node. The right node will contain an identification
key that is larger than the current one.
Indicates the address of the post-search confirmation structure that will be used to route
this packet if it matches the identification key.
Table 18 - Fields and Description
When the correct node associated with the packet is found, the post-search confirmation structure will indicate what
course of action to take concerning the packet. It may indicate to route the packet to the Packet Disassembly, to the
RX CPU buffer or onto network port A or B. It may also indicate that another look-up needs to be performed, this
time using a different look-up profile. The process then begins anew using the new profile
Other look-ups can take place in the binary tree: for example, ELAN-IDs contained in LANE v2 packets can be
looked up, along with the Flow Table Pointer. A CRC will be performed on the fields, a 60-bit key will be generated,
and a post-search entry will be obtained. This entry can be used to modify the Flow Table Pointer and the parsing of
the packet will then continue with the new pointer.
MPOA tags and MPLS labels can also be searched for in the binary tree and post-search structures: apart from
modifying the Flow Table Pointer, these searches are also used to identify the nature of the protocol above MPOA
or MPLS. When packets are first assembled in the AAL5 reassembly structure, the nature of the protocols above
these two are tagged in the fields MPLS_IP and MPOA_IP. When an MPOA or MPLS header is found in the packet
and the nature of the following protocol has not been established, this header is looked-up along with the Flow
Table Pointer. The resulting structure will identify the following protocol and may also change the Flow Table
Pointer. The packet analysis then strips the MPOA or MPLS header off and continues the binary tree search with
the following protocol.
Zarlink Semiconductor Inc.
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