Date: Fri, 28 May 1999 08:40:02 +0200 From: Andreas Klemm <andreas@klemm.gtn.com> To: freebsd-net@freebsd.org, zebra@zebra.org Cc: Kunihiro Ishiguro <kunihiro@zebra.org> Subject: OSPF eequal-cost paths, which algorithm, how exactly load balancing ? Message-ID: <19990528084002.A41138@titan.klemm.gtn.com>
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Hi !
I'm looking for the algorithm how OSPF does a routing decision and
what kind of load balancing is been done, between the two 4 MBit
leased lines, when OSPF has equal-cost paths like this.
Cisco IOS 11.2 or 11.3.
Rstart
|e0
|10MBit
|
-----------+----------------
|10MBit |10MBit
|e0 |e0
| |
R1 R3
|| ||
s0||s1 s0||s1 load balancing between 2 serial
||2x2=4MBit ||2x2=4MBit (4 MBit, process switching to get
|| || load balancing between 2 serial
|| ||
R2 R4
| |
|10MBit |10MBit
|e0 |e0
-----------+-----------------
|
|10 MBit
|e0
Rdest
All I read in the OSPF V2 RFC is, that OSPF creates one routing
entry for the interface Rstart e0, that has to destinations
R1 and R3 and that it does a load sharing between the two ways,
but how ?
How is the routing decision being done. What impact does load
have on a routing decision and how often it is re-calculated ???
When is perhaps only one route used between R1-R2 or R3-R4 ?
The question is, in an redundant environment, how well does OSPF
scale when it comes to the point of question, are and how well
are the links shared. Do users get 2 x 4 = 8 MBit throughput or
only 1 x 4 MBit ???
Thanks a lot, if you could help me on this one.
--
Andreas Klemm http://www.FreeBSD.ORG/~andreas
http://www.freebsd.org/~fsmp/SMP/SMP.html
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