Datasheet

____________________________________________________ DS34T101, DS34T102, DS34T104, DS34T108
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10.6.13 Packet Classifier
The Packet Classifier is part of the receive path, immediately following the Ethernet MAC block. It analyzes the
header of each incoming packet, by comparing the header fields to the chip’s configured parameters, and then
decides whether to discard the packet or add a buffer descriptor and forward the packet to the CPU or one of the
payload-type machines. Section 11.4.1 has re
gister descriptions for the packet classifier configuration registers.
IP version:
 Packets with IP version different than 4 or 6 are always discarded.
 The chip has three IPv4 addresses and two IPv6 addresses (all software configurable)
 The chip works in one of four modes defined by two bits in General_cfg_reg1, as de
scribed in Table 10-29.
Table 10-29. Handling IPv4 and IPv6 Packets
IP_version Dual_stack
Transmitted
Packe
ts IP Version
Received Packets IP Version
0 0 IPv4
Receive only IPv4 packets (other IP
versions are discarded)
1 0 IPv6
Receive only IPv6 packets (other IP
versions are discarded)
0 1 IPv4
Receive both IPv4 and IPv6 packets (dual
stack mode)
1 1 IPv6
Receive both IPv4 and IPv6 packets (dual
stack mode)
Although the chip has more than one IP address, in most cases all three IPv4 addresses should have the same
value and both IPv6 addresses should have the same value. The chip also has two configurable MAC addresses.
Packets with CRC errors are discarded regardless to their contents, unless the Ethernet MAC has been configured
to ignore them (in which case they are treated as correct packets).
IP Packets with IP checksum error are discarded, unless the Discard_ip_checksum_err config
uration bit is cleared
in General_cfg_reg0.
Packets othe
r than TDM-over-IP or TDM-over-MPLS or TDM-over-MEF packets destined to the chip are not
transferred to the payload-type machines. Instead, they are either discarded or transferred to the CPU according to
the nine Discard_switch
configuration bits in Packet_classifier_cfg_reg3:
Discard_Switch_0: An ARP packet whose Ipv4 destination address is not identical to any of the chip’s
Ipv4 addresses is discarded if Discard_Switch_0 is set. Otherwise it is transferred to
the CPU.
Discard_Switch_1: An IP (both Ipv4 or Ipv6) packet whose IP destination address is not identical to any of
the chip’s IP addresses is discarded if Discard_Switch_1 is set. Otherwise it is
transferred to the CPU.
Discard_Switch_2: A packet whose Ethertype is not known by the block is discarded if Discard_Switch_2
is set. Otherwise it is transferred to the CPU.
Discard_Switch_3: An ARP packet whose Ipv4 destination address is identical to one of the chip’s Ipv4
addresses is discarded if Discard_Switch_3 is set. Otherwise it is transferred to the
CPU.
Discard_Switch_4: An IP packet destined to the chip whose protocol is different than UDP and L2TPv3 is
discarded if Discard_Switch_4 is set. Otherwise it is transferred to the CPU.
Discard_Switch_5: An IP/UDP packet destined to the chip whose UDP destination/source port number is
not identical to one of the chip’s TDM-over-Packet port numbers (according to
TDMoIP_port_num_loc in Packet_classifier_cfg_reg3)
is discarded if
Discard_Switch_5 is set. Otherwise it is transferred to the CPU.
Discard_Switch_6: A TDMoP/MPLS/MEF packet destined to the chip whose bundle identifier is not
identical to one of the chip’s OAM Bundle Numbers or one of the bundle identifiers