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OSPF load balancing on default route

I have three routers. Router A gets a default route from Router B and Router C. But I would like to verify if ospf load balancing is working on the default route. I been monitoring the network traffic and noticed 95% of network traffic from Router A is going through Router B.

Below are some of the show commands I did on router A

Routing entry for 0.0.0.0/0, supernet
Known via "ospf 100", distance 110, metric 1, candidate default path
Tag 100, type extern 2, forward metric 1
Last update from 192.168.239.29 on Vlan798, 03:18:21 ago
Routing Descriptor Blocks:
* 192.168.239.29, from 192.168.239.254, 03:18:21 ago, via Vlan798
Route metric is 1, traffic share count is 1
Route tag 100
192.168.239.25, from 192.168.239.253, 03:18:21 ago, via Vlan799
Route metric is 1, traffic share count is 1
Route tag 100

-----------------------------------------------------------------------------
Router#sh ip cef 0.0.0.0
0.0.0.0/32
receive

-------------------------------------------------------------------------------
Router#sh ip protocol
*** IP Routing is NSF aware ***

Routing Protocol is "ospf 100"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 192.168.239.250
It is an autonomous system boundary router
Redistributing External Routes from,
connected, includes subnets in redistribution
static, includes subnets in redistribution
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
192.168.239.24 0.0.0.3 area 0
192.168.239.28 0.0.0.3 area 0
Routing Information Sources:
Gateway Distance Last Update
192.168.239.251 110 03:19:07
192.168.239.254 110 03:19:07
192.168.239.252 110 03:19:07
192.168.239.253 110 03:19:07
Distance: (default is 110)

--------------------------------------------------------------------------------
Router#sh ip cef 0.0.0.0 internal
0.0.0.0/32, epoch 4, flags receive, refcount 6, per-destination sharing
sources: Spc
feature space:
Broker: linked
subblocks:
Special source: receive
ifnums: (none)
path 47CB8398, path list 47CB2B50, share 1/1, type receive, for IPv4
receive
output chain: receive

naderz

Do you have the "show ip route" results?

ShadowColossus

ASKER

Sorry,

The output is below is the output for show ip route 0.0.0.0.

Routing entry for 0.0.0.0/0, supernet
Known via "ospf 100", distance 110, metric 1, candidate default path
Tag 100, type extern 2, forward metric 1
Last update from 192.168.239.29 on Vlan798, 03:18:21 ago
Routing Descriptor Blocks:
* 192.168.239.29, from 192.168.239.254, 03:18:21 ago, via Vlan798
Route metric is 1, traffic share count is 1
Route tag 100
192.168.239.25, from 192.168.239.253, 03:18:21 ago, via Vlan799
Route metric is 1, traffic share count is 1
Route tag 100

naderz

you do have both routes in the table as expected. you also have cef; which is actually handling the load-balancing on a per destination basis. so, it is possible that one destination may have many sources from inside and that could put all traffic on one route. one such destination could be e.g. Facebook.

you can experiment with fine tuning cef. let me know if you are interested.

Phyo HTET AUNG

cef default load balancing is per-destination which source-destination address pair. How many source network do you have in RouterA in this case?

ASKER CERTIFIED SOLUTION

naderz

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