Protocol Support; Types Of Teams - Dell Broadcom NetXtreme Family of Adapters User Manual

each link (Inbound Flow Entries) represents an IP host located in the same subnet.
When an inbound IP Datagram arrives, the appropriate Inbound Flow Head Entry is located by hashing the source IP address
of the IP Datagram. Two statistics counters stored in the selected entry are also updated. These counters are used in the
same fashion as the outbound counters by the load-balancing engine periodically to reassign the flows to the physical
adapter.
On the inbound code path, the Inbound Flow Head Hash Table is also designed to allow concurrent access. The link lists of
Inbound Flow Entries are only referenced in the event of processing ARP packets and the periodic load balancing. There is no
per packet reference to the Inbound Flow Entries. Even though the link lists are not bounded; the overhead in processing
each non-ARP packet is always a constant. The processing of ARP packets, both inbound and outbound, however, depends on
the number of links inside the corresponding link list.
On the inbound processing path, filtering is also employed to prevent broadcast packets from looping back through the
system from other physical adapters.

Protocol Support

ARP and IP/TCP/UDP flows are load balanced. If the packet is an IP protocol only, such as ICMP or IGMP, then all data flowing
to a particular IP address will go out through the same physical adapter. If the packet uses TCP or UDP for the L4 protocol,
then the port number is added to the hashing algorithm, so two separate L4 flows can go out through two separate physical
adapters to the same IP address.
For example, assume the client has an IP address of 10.0.0.1. All IGMP and ICMP traffic will go out the same physical adapter
because only the IP address is used for the hash. The flow would look something like this:
IGMP ------> PhysAdapter1 ------> 10.0.0.1
ICMP ------> PhysAdapter1 ------> 10.0.0.1
If the server also sends an TCP and UDP flow to the same 10.0.0.1 address, they can be on the same physical adapter as
IGMP and ICMP, or on completely different physical adapters from ICMP and IGMP. The stream may look like this:
IGMP ------> PhysAdapter1 ------> 10.0.0.1
ICMP ------> PhysAdapter1 ------> 10.0.0.1
TCP------> PhysAdapter1 ------> 10.0.0.1
UDP------> PhysAdatper1 ------> 10.0.0.1
Or the streams may look like this:
IGMP ------> PhysAdapter1 ------> 10.0.0.1
ICMP ------> PhysAdapter1 ------> 10.0.0.1
TCP------> PhysAdapter2 ------> 10.0.0.1
UDP------> PhysAdatper3 ------> 10.0.0.1
The actual assignment between adapters may change over time, but any protocol that is not TCP/UDP based goes over the
same physical adapter because only the IP address is used in the hash.
Performance
Modern network interface cards provide many hardware features that reduce CPU utilization by offloading certain CPU
intensive operations (see Teaming and Other Advanced Networking Properties). In contrast, the BASP intermediate driver is a
purely software function that must examine every packet received from the protocol stacks and react to its contents before
sending it out through a particular physical interface. Though the BASP driver can process each outgoing packet in near
constant time, some applications that may already be CPU bound may suffer if operated over a teamed interface. Such an
application may be better suited to take advantage of the failover capabilities of the intermediate driver rather than the load
balancing features, or it may operate more efficiently over a single physical adapter that provides a particular hardware
feature such as Large Send Offload.

Types of Teams