Riverstone Networks WICT1-12 - Manual (Page 109)

Riverstone Networks RS Switch Router User Guide Release 8.0 6-9
SmartTRUNK Configuration Guide SmartTRUNK Load Redistribution
6.4 SMARTTRUNK LOAD REDISTRIBUTION
SmartTRUNK Load Redistribution (SLR) monitors all ports within a SmartTRUNK for utilization. If a port begins to
become overloaded, SLR automatically moves some of the port’s flows to other, less utilized ports within the
SmartTRUNK. SLR is enabled for the entire SmartTRUNK, and can be used in unison with any control protocol or
load policy (see
Section 6.1.3, "Specifying Traffic Load Policy" and Section 6.3.1, "Configuring SmartTRUNKs for
LACP" ).
Note When a SmartTRUNK is created, one of the ports is elected for sending and
receiving layer-2 multicast and broadcast traffic. SLR leaves these layer-2
multicast or broadcast flows unaffected.
Note Each time a redistribution is performed by SLR, an SNMP trap is generated.
6.4.1 SLR Water-marks
SLR uses “water-marks,” based on percentage port utilization, to determine whether flows on a port need to be
redistributed to other ports within the SmartTRUNK.
SLR uses the three following user-defined water-marks:
• Low water-mark (
lwm
) – Used by SLR to detect whether a port is under utilized; the default is 20%
of bandwidth
• Medium water-mark (
mwm
) – Used by SLR as a baseline of normal port utilization; the default is 50%
of bandwidth
• High water-mark (
hwm
) – Used by SLR to detect whether a port is over utilized; the default is 80%
of bandwidth
Note Water-marks are set on a per-SmartTRUNK basis, i.e., water-marks cannot be set
on a per-port basis.
6.4.2 Polling intervals
SLR uses two intervals to perform load redistribution:
Status Interval – Interval in which port utilization information is gathered; the default is one second.
Redistribution Interval – Interval in which SLR considers flows for redistribution. The Redistribution Interval is the
number of Status Intervals that must pass before flows are considered for redistribution.The Redistribution Interval
relates to a number of Status Intervals, as opposed to being a measure of time; the default is 5 Status Intervals.
To determine the length of time in seconds for one Redistribution Interval, multiply the Status Interval by the
Redistribution Interval value. For example, using the defaults,