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OS6624/6648 Architecture
page -52 OmniSwitch Troubleshooting Guide September 2005
Tag Net ID Entry
• Contains related information like tagged set and member set. A 4x32 bit entry is present for every
possible VLAN (4096 supported).
• VLAN Tag Valid. Indicates if this VLAN tag has been configured by the CPU. If not, all packets with
this tag are dropped.
• Ports on which a packet with this Tag can go out on.
• VLAN Statistics Index. IXE2424 can collect statistics on up to 15 VLANs, identified by this index.
• IP Statistics Index. The IXE2424 can collect statistics on up to 256 IP Routed packets, identified by
this index.
• Tagged Set Port indicates which ports have nodes attached that can accept tagged packets on this
VLAN; packets are forwarded untagged to ports that cannot accept the tagged packets.
• Multicast Forward indicates which ports are disabled from transmitting unregistered multicast packets
on this VLAN. If the bit is set for a particular port, unregistered multicast packets are not transmitted
on that port.
• Priority, Bandwidth Management and QOS
Priority
• Each port on the IXE2424 has four output/transmit queues that store pointers to packets to be transmit-
ted. Each queue corresponds to one distinct priority level. Packets in higher priority queues are serviced
before packets in lower priority queues. These transmit queues support weighted fair queuing as well as
strict priority queuing algorithms.
• The IXE2424 supports three methods of assigning device priority to a packet: 802.1p Priority, Rules-
based Priority and QoS flow.
802.1p Priority
The incoming packet may have a priority associated with its 802.1Q Tag. 802.1p priority specifies eight
levels of priority. This priority level is mapped to one of the four device priority levels (per port) using the
Priority Map Register. Note this Priority Map Register applies to all ports on the IXE2424. If the incom-
ing packet is untagged, it is assigned a default 802.1p priority level of zero. However, the priority regener-
ation feature may be used to change this priority level on a per-port basis using the Port Regenerate Tag
Priority Level Entry Register.