Load Balanceing problem.........!

Unanswered Question
Mar 23rd, 2007
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I have two link between to locations each of 16MB..


We are using SDM link between to router.


COnfig on router 1

====================


ip cef


inte gig0/1

ip ADDRESS 1.1.1.1 25.0.0.0

ip load shareing per-packet

no ip proxy-arp

no ip mroute-cache

no autonegotiation

load-interval 30

dulpex full

speed 100

media type RJ45




inte gig0/0

ip ADDRESS 2.2.2.1 25.0.0.0

ip load shareing per-packet

no ip proxy-arp

no ip mroute-cache

no autonegotiation

load-interval 30

dulpex full

speed 100

media type RJ45



ip route 172.16.2.0 255.255.255.0 1.1.1.2


ip route 172.16.2.0 255.255.255.0 2.2.2.2



===================

COnfig on router2

===================


ip cef


inte gig0/1

ip ADDRESS 1.1.1.2 25.0.0.0

ip load shareing per-packet

no ip proxy-arp

no ip mroute-cache

no autonegotiation

load-interval 30

dulpex full

speed 100

media type RJ45




inte gig0/0

ip ADDRESS 2.2.2.2 25.0.0.0

ip load shareing per-packet

no ip proxy-arp

no ip mroute-cache

no autonegotiation

load-interval 30

dulpex full

speed 100

media type RJ45



ip route 172.16.1.0 255.255.255.0 1.1.1.1


ip route 172.16.1.0 255.255.255.0 2.2.2.1



Now with this config...


When i m doing FTP(20 MB) from host A to Host B then i geting very low threwput on both link....i m geting aound 20%

therwput.


If i remove one link then i m geting 100% thoughput on the remained link.


PLease let me know where is root cause of problem ?If u are haveing any alternate solutions for same (to load balance )let me know.




===========Please see attachment for Toplogy=========



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Kypamop Fri, 03/23/2007 - 11:16
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Hi!


Let me see your:


1) show ip cef 172.16.1.0 detail

2) show ip cef gig 0/0 detail

show ip cef gig 0/1 detail

3) show ip int gig 0/0

show ip int gig 0/1


Also, the cause of low throughput might be the process switching mode on one the interfaces, please check if you are experiencing high CPU utilization during ftp transfer.

ganpatspatil Sun, 03/25/2007 - 21:31
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Hi Kypamop ,


Please see the attachment for command output.

Let me know different configuration option so i can try with the same.....As i don't have full time access to this secnario i may not give full output...So pls tell me diffent config options.......thanks



Attachment: 
Kypamop Mon, 03/26/2007 - 01:54
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Hi!


Unfortunately this output isn't enough to solve your issue.


I've tried your scenario on emulator: "show" commands show that load balancing was activated, but I can't say for sure if this actually works.


Try to get output of commands I've posted you before.

Richard Burts Mon, 04/09/2007 - 20:33
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Ganpat


When I see that someone is configuring load sharing to do per packet load balancing I am concerned about the impact of out of order packets. While I do not know for sure if this is the cause of your problem I would suggest that you investigate this possibility.


Is it possible to get some protocol analyzer (Sniffer/Ethereal/etc) to capture and analyze this traffic? If so run the transfer and look for retransmissions/lost packets.


If it is not possible to do a packet capture there are a couple of things that might be helpful in the investigation on the router. Configure the load interval on all 4 interfaces to the minimum value. Then I would suggest that you transfer the same file several times (once with both links active, once with only one link, and once with only the other link). I would suggest doing clear interface counters before each transfer, and then show interface commands several times while each transfer is being done, and then at the end of each transfer. I would look at the total number of packets transferred and check to see if the total packets was the same when both links are used as the number of packets when a single link is used. If the number of packets is larger when both links are used then it is probably a sign of packet loss and retransmission.


I would also look at the show interface output done while that transfer is being done on the two single links. I would look at the number of bytes per second being transferred. Are the same number of bytes being transfer over link 1 as are transferred over link 2? If there is much difference in number of bytes per second there there is some performance difference between the links and this could lead to out of order packets, packet loss, packet retransmission, and worse performance with both links are in use.


HTH


Rick

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