Re: OSPF - Load balancing

maybe some of this will get you going in the right direction...

by default OSPF does equal cost load balancing:

http://www.cisco.com/en/US/tech/tk365/technologies_q_and_a_item09186a0080094704.shtml#q37

simple example to see it and also change the defaults to get into load
balance over "unequal cost" paths by making them equal:
R1#sh ip int br | e una
Interface IP-Address OK? Method Status
Protocol
FastEthernet0/0 1.1.1.1 YES manual up
up
Serial0/0 3.3.3.1 YES manual up
up
FastEthernet0/1 2.2.2.1 YES manual up
up
Serial0/1 4.4.4.1 YES manual up
up
Loopback100 100.100.100.100 YES manual up
up

R2#sh ip int brief
Interface IP-Address OK? Method Status
Protocol
FastEthernet0/0 1.1.1.2 YES manual up
up
Serial0/0 3.3.3.2 YES manual up
up
FastEthernet0/1 2.2.2.2 YES manual up
up
Serial0/1 4.4.4.2 YES manual up
up
Loopback200 200.200.200.200 YES manual up
up

R2#sh ip route 100.100.100.100
Routing entry for 100.100.100.100/32
  Known via "ospf 1", distance 110, metric 11, type intra area
  Last update from 2.2.2.1 on FastEthernet0/1, 00:03:50 ago
  Routing Descriptor Blocks:
    2.2.2.1, from 0.0.1.0, 00:03:50 ago, via FastEthernet0/1
      Route metric is 11, traffic share count is 1
  * 1.1.1.1, from 0.0.1.0, 00:03:50 ago, via FastEthernet0/0
      Route metric is 11, traffic share count is 1
R2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#int s0/1
R2(config-if)#ip os
R2(config-if)#ip ospf co
R2(config-if)#ip ospf cost 10
R2(config-if)#int s0/0
R2(config-if)#ip ospf cost 10
R2(config-if)#do sh ip route 100.100.100.100
Routing entry for 100.100.100.100/32
  Known via "ospf 1", distance 110, metric 11, type intra area
  Last update from 4.4.4.1 on Serial0/1, 00:00:23 ago
  Routing Descriptor Blocks:
    4.4.4.1, from 0.0.1.0, 00:00:23 ago, via Serial0/1
      Route metric is 11, traffic share count is 1
    3.3.3.1, from 0.0.1.0, 00:00:23 ago, via Serial0/0
      Route metric is 11, traffic share count is 1
    2.2.2.1, from 0.0.1.0, 00:04:40 ago, via FastEthernet0/1
      Route metric is 11, traffic share count is 1
  * 1.1.1.1, from 0.0.1.0, 00:04:40 ago, via FastEthernet0/0
      Route metric is 11, traffic share count is 1

and also a quick look at the CEF table for that route for per-packet vs.
per-destination:

R2#sh ip cef 100.100.100.100
100.100.100.100/32, version 29, epoch 0, per-destination sharing
0 packets, 0 bytes
  via 4.4.4.1, Serial0/1, 0 dependencies
    traffic share 1
    next hop 4.4.4.1, Serial0/1
    valid adjacency
  via 3.3.3.1, Serial0/0, 0 dependencies
    traffic share 1
    next hop 3.3.3.1, Serial0/0
    valid adjacency
  via 2.2.2.1, FastEthernet0/1, 0 dependencies
    traffic share 1
    next hop 2.2.2.1, FastEthernet0/1
    valid adjacency
  via 1.1.1.1, FastEthernet0/0, 0 dependencies
    traffic share 1
    next hop 1.1.1.1, FastEthernet0/0
    valid adjacency
  0 packets, 0 bytes switched through the prefix
  tmstats: external 0 packets, 0 bytes
           internal 0 packets, 0 bytes
R2(config-if)#int f0/0
R2(config-if)#ip load-sharing per-packet

R2(config-if)#do clear ip route *

R2(config-if)#do sh ip cef 100.100.100.100
100.100.100.100/32, version 27, epoch 0, per-packet sharing
0 packets, 0 bytes
  via 4.4.4.1, Serial0/1, 0 dependencies
    traffic share 1, current path
    next hop 4.4.4.1, Serial0/1
    valid adjacency
  via 3.3.3.1, Serial0/0, 0 dependencies
    traffic share 1
    next hop 3.3.3.1, Serial0/0
    valid adjacency
  via 2.2.2.1, FastEthernet0/1, 0 dependencies
    traffic share 1
    next hop 2.2.2.1, FastEthernet0/1
    valid adjacency
  via 1.1.1.1, FastEthernet0/0, 0 dependencies
    traffic share 1
    next hop 1.1.1.1, FastEthernet0/0
    valid adjacency
  0 packets, 0 bytes switched through the prefix
  tmstats: external 0 packets, 0 bytes
           internal 0 packets, 0 bytes
http://www.cisco.com/en/US/products/hw/modules/ps2033/prod_technical_reference09186a00800afeb7.html

--
Garry L. Baker
"There is no 'patch' for stupidity." - www.sqlsecurity.com
On Sat, Jul 31, 2010 at 10:26 AM, Mohammed Aftab Memon <
aftabmemon12_at_gmail.com> wrote:
> Hello All,
>
> There was some problem with my yahoo id and from days I was not getting any
> emails from this group.
>
> Please assist me on my below query.
> *
> Quote\\
> *Hello Group,
>
> I have completed my preparation for OSPF but still feel that there is
> something missing.
>
> When I compared it with other protocols I realized that the Load balancing
> over OSPF is not done.
>
> I have been though video material of different vendors but stll I did not
> find in any of them.
>
> MIght be I am wrong or might be I did not concentrate if they did cover
> that
> topic during their lecture.
>
> I did find something related to load balancing which talks about Max - lsa.
>
> Can some one please advise me on this.
>
>
> Like if we have 2 routers with 3 redundant link between them, how wil the
> ospf load balance between them ?
>
>
> Also is there any specific command with which we can see only the flow of
> LSA's ?
>
> *Unquote*
>
> Regards
> Mohammed Aftab Memon
>
> --- On *Sun, 25/7/10, Aftab Memon <aftab.memon_at_ymail.com>* wrote:
>
>
> From: Aftab Memon <aftab.memon_at_ymail.com>
> Subject: Fw: OSPF - Load balancing
> To: "ccielab" <ccielab_at_groupstudy.com>
> Date: Sunday, 25 July, 2010, 6:37 AM
>
>  FYI Group
>
> Regards,
>
> Mohd Aftab MEMON
> Network Analyst
>
> --- On *Sat, 24/7/10, Aftab Memon <aftab.memon_at_ymail.com>* wrote:
>
>
> From: Aftab Memon <aftab.memon_at_ymail.com>
> Subject: OSPF - Load balancing
> To: ccielab_at_groupstudy.com
> Date: Saturday, 24 July, 2010, 5:49 AM
>
>  Hello Group,
>
> I have completed my preparation for OSPF but still feel that there is
> something missing.
>
> When I compared it with other protocols I realized that the Load balancing
> over OSPF is not done.
>
> I have been though video material of different vendors but stll I did not
> find in any of them.
>
> MIght be I am wrong or might be I did not concentrate if they did cover
> that
> topic during their lecture.
>
> I did find something related to load balancing which talks about Max - lsa.
>
> Can some one please advise me on this.
>
>
> Like if we have 2 routers with 3 redundant link between them, how wil the
> ospf load balance between them ?
>
>
> Also is there any specific command with which we can see only the flow of
> LSA's ?
>
> Regards,
>
> Mohd Aftab MEMON
> Network Analyst
>
>
> Blogs and organic groups at http://www.ccie.net
>
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