Load Sharing On The Switch 9100; Load Sharing Algorithms - 3Com 9100 User Manual

58 C 3: A
HAPTER CCESSING THE
Load Sharing on
the Switch 9100
Load Sharing
Algorithms
S
WITCH
Load sharing with Switch 9100 devices allows you to increase bandwidth
and resilience between switches by using a group of ports to carry traffic
in parallel between switches. The sharing algorithm allows the switch to
use multiple ports as a single logical port. For example, VLANs see the
load-sharing group as a single logical port. The algorithm also typically
guarantees packet sequencing between clients.
If a port in a load-sharing group fails, traffic is redistributed to the
remaining ports in the load-sharing group. If the failed port becomes
active again, traffic is redistributed to include that port.
Load sharing must be enabled on both ends of the link, or a network
loop will result. The load sharing algorithms do not need to be the same
on both ends of the link.
Load sharing is most useful in cases where the traffic transmitted from
the switch to the load-sharing group is sourced from an equal or greater
number of ports on the switch. For example, traffic transmitted to a
two-port load-sharing group should originate from a minimum of two
other ports on the same switch.
This feature is supported between Switch 9100 devices only, but may be
compatible with third-party "trunking" or sharing algorithms. Check with
your supplier for more information.
Load sharing algorithms allow you to select the distribution technique
used by the load-sharing group to determine the output port selection.
Algorithm selection is not intended for use in predictive traffic
engineering. You can configure one of three load-sharing algorithms on
the switch, as follows:
Port-based — Uses the ingress port to determine which physical port
in the load-sharing group is used to forward traffic out of the switch.
Address-based — Uses addressing information to determine which
physical port in the load-sharing group to use for forwarding traffic
out of the switch. Addressing information is based on the packet
protocol, as follows:
IP packets — Uses the source and destination MAC and IP
addresses, and the TCP port number.
IPX packets — Uses the source and destination MAC address, and
IPX network identifiers.