A look at your configs would be helpful, but some thoughts...
Are you doing per-packet load balancing or per-destination (the default)?
If you are doing per-destination, how many different destinations is your
traffic going to? You may be getting 'pinhole congestion', where due to
caching all traffic (or a significant proportion of it) goes down one
link. This can be a problem even if you have lots of destinations, if one
destination gets a lot of traffic (for example, large FTP transfers).
Make sure that you have the same form of caching on each interface. If
you have one interface set for per-packet, and one for per-destination,
all traffic will rapidly end up on the per-destination interface (why is
left as an exercise for the reader - it's been discussed before so should
be in the archives if you can't work it out)
JMcL
----- Forwarded by Jenny Mcleod/NSO/CSDA on 17/01/2002 01:47 pm -----
"Elijah Savage"
Sent by: [EMAIL PROTECTED]
17/01/2002 12:42 pm
Please respond to "Elijah Savage"
To: [EMAIL PROTECTED]
cc:
Subject: 2 T1 load balancing not working [7:32239]
All,
I had to setup a 2621 to do load balancing over 2 t1's with ospf. I know
ospf does this on a basic simple default setup. So after setting this up
everything seemed to be working great but one link was definately being
used about 80% more than the other. So after doing some reasearch on cco
I realized my problem I had ip route-cache turned on under the interface
on both serial interfaces. According to
http://www.cisco.com/warp/public/105/46.html it works alot better by
turning this off so I did and was getting just about 50/50 load
balancing accross both t1's. But in my quest of always trying to make
the network more efficient I saw at the bottom of that page on the link
above this statement below.
Newer switching schemes such as Cisco Express Forwarding (CEF)
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/s
witch_c/xcprt2/xccefc.htm allow you to do per-packet and per-destination
load-balancing more quickly. However, it does imply that you have the
extra resources to deal with maintaining CEF entries and adjacencies.
Refer to this Application Note
for more
information on load-sharing with CEF.
So I went of the info on that URL to setup ip cef on the router and ip
load sharing. But after clearing the counters and doing a show interface
I could see all traffic going accross only one serial interface. I am
using IOS 12.1 and I had ip cef turned on globally and on both
interfaces locally as the doc stated, but only 1 link was being used.
Any ideas why?
, ,
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