From: Mohamed Heeba (MAHeeba@xxxxxxxxxxx)
Date: Tue May 08 2001 - 17:51:23 GMT-3
HI
thx for the explanation ..but still i have few things here
does the load be redistributed equally between the links?or based on the
bandwidth ratio ?? i read somewhere that a protocol is doing load balancing
based on the b.w ratio ( when we use the variance command with OSPF for
example ).
second thing is that what u explained is right ,the deactivate-load value as
explained in the command reference is the ratio (or percentage) of the
total load on both links measured to the primary link full load or in maths
like that
(load on primary +load in backup )/primary full load %.
on the fatkid lab (which i want to verify ) the requirement is to drop the
backup when the primary is 25% utilized ,as i understand this , the exact
load at this point will be double of the 25% .
the solution is showing 10% ??? so im still confusing or may i understand
something wrong .
have a look on it if u have time
thx
> -----Original Message-----
> From: Wayne Gustavus [SMTP:wgustavus@mentortech.com]
> Sent: Tuesday, May 08, 2001 8:50 AM
> To: 'Mohamed Heeba'; lkouncar@UU.NET; ccielab@groupstudy.com
> Subject: RE: Fatkid 505 ,dail backup question
>
> I believe the proper way to interpret the syntax of the command is more
> basic than what you described. The percentages that are used in the
> backup
> load command are definitely in relation to the available bandwidth of the
> primary interface. The description of the disable-load threshold is
> trying
> to convey the idea that the *total* traffic must be less than the value
> derived from the disable-load threshold before *all* traffic will be moved
> back to the primary link and the backup link is shut down.
>
> For example, suppose you have a primary link with a bandwidth of 100Kbps
> defined and the command "backup load 20 10". (I know the numbers may be
> unrealistic but it makes the math easy and is easy to test)
> If there is 50Kbps of traffic on the primary interface then there is a 50%
> load and the secondary link will be activated. If the router balances the
> traffic across the 2 links (don't forget about ip route-cache) then 25Kbps
> will travel across both the primary and secondary.
>
> Now suppose the traffic source(s) slows down and there is 18Kbps traffic
> presented to the network. This will result in approx 9Kbps on the primary
> and secondary. However, since the total traffic rate is still 18kbps, the
> 10% kick-out (or 10Kbps, since it is 10% of the primary's 100Kbps
> bandwidth)
> the secondary stays active.
>
> Finally, if the traffic source(s) slows its rate to 8Kbps, the primary and
> secondary will each carry approximately 4Kbps of traffic. Since the
> *total*
> traffic rate is below the 10% kick-out rate, the secondary link will
> revert
> to 'normal operation' and go into standby mode. The primary link will
> then
> carry the entire 8Kbps.
>
> The BOTTOM LINE is to think of the disable-load value as the traffic rate
> which the primary link 'decides' it doesn't need the help of the secondary
> any more. This rate is calculated as a percentage of the primary link's
> bandwidth. Therefore, the bandwidth of the secondary link does not factor
> into the equation at all (BTW, even though it isn't relevant to this
> issue,
> you may want to double check the BW of the BRI interface with a "sh int
> bri0"; I think you will find it is 64Kb even though you effectively have
> 128Kb with the 2 B-channels)
>
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