From: Chua, Parry (Parry.Chua@xxxxxxxxxx)
Date: Sun Nov 18 2001 - 06:38:04 GMT-3
Hi,
I thought that when we show IP route, there could be one or more path to
reach a particular destination based on the routing protocol type. For
OSPF, if we know there could be more than one path to reach that
destination, we can then manuiplate the COST to get a equal cost
for load balanceing, right ? Other protocolos such as (E)IGRP support
unequal cost load balancing. As for RIP, I belive we can use offset to
change the hop count from unequal to
equal and vice versa, right ?
Regards
Parry
-----Original Message-----
From: tom cheung [mailto:tkc9789@hotmail.com]
Sent: Sunday, November 18, 2001 10:31 AM
To: hbae@nyc.rr.com; ccielab@groupstudy.com
Subject: Re: OSPF Load Balance
I'll have to disagree, and someone else please correct me if I'm wrong.
OSPF only understands intra-area, inter-area and external route types.
OSPF
route preference is based upon route types and within the same route
type,
costs. If there're equal cost routes within the same route type, then
load
balance is automatic. Sure you can look at same cost as hop counts. If
I
make the cost of two paths to the same destination, say 100, you
certainly
can view that as 100 hops. But load balance will happen.
If there're no equal cost paths to the same destination, fast switch
will
not put packets on the higher cost path, period.
Tom
>From: Hansang Bae <hbae@nyc.rr.com>
>Reply-To: Hansang Bae <hbae@nyc.rr.com>
>To: ccielab@groupstudy.com
>Subject: Re: OSPF Load Balance
>Date: Sat, 17 Nov 2001 20:14:20 -0500
>
>>>From: Hansang Bae <hbae@nyc.rr.com>
>>>I don't think you accomplished what you wanted to do. Setting all
the
>>>costs to be the same causes OSPF to act like RIP. That is, the
metric
>>>now
>>>becomes a hop count. So unless you have the same number of hops, it
>>>won't
>>>work.
>>>Even then, route-cache will cause per destination load-balancing.
>
>
>At 10:17 AM 11/17/2001 -0600, tom cheung wrote:
>>Correct me if I'm wrong. By default, OSPF load balances up to a max
of 4
>>equal cost, equal path-type routes. OSPF does not take into
consideration
>>of hop counts.
>
>
>
>All correct. *Except*, that the original poster made all the interface
>costs to be the same. So basically, the metric acts just like hop
counts.
>And while load balancing works across 4 links (w/o using
maximum-paths),
>the route-cache (fast processing) makes the router use one link for a
>particular destination. This isn't unique to OSPF, it's just the way
fast
>processing works (w/o using CEF etc.)
>
>hsb
This archive was generated by hypermail 2.1.4 : Fri Jun 21 2002 - 06:45:17 GMT-3