CCIE Pursuit Blog

May 22, 2009

Core Knowledge Question of the Day: 22 May 2009

Filed under: Cisco,Cisco Certification — cciepursuit @ 8:01 am
Tags: , , , ,

r6#sh ip route 30.2.0.0
Routing entry for 30.2.0.0/16
Known via “ospf 100”, distance 110, metric 20, type extern 2, forward metric 1
Last update from 155.1.146.4 on FastEthernet0/0, 00:29:54 ago
Routing Descriptor Blocks:
* 155.1.146.4, from 150.1.4.4, 00:29:54 ago, via FastEthernet0/0
Route metric is 20, traffic share count is 1

If we change the above route from an OSPF E2 to an OSPF E1 route, what will the route metric be?

Highlight for answer: 21. E1 routes compute the OSPF metric “end-to-end”, whereas E2 routes only compute the OSPF metric from the ASBR onwards. In the output above the ‘forward metric’ represents the metric to reach the ASBR.  When the route is converted to an E1, the forward cost is added to the existing metric to form the E1 metric.

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2 Comments »

  1. metric will not be changed..this subnet is redistributed from anohter protocol without configuring metric..by default ospf router takes this as metric 20..am i right???

    Comment by vijay — June 20, 2009 @ 12:34 am | Reply

  2. 21 = 20 TO REACH asbr + 1 FORWARD METRIC. am I RIGHT

    Comment by MOHAMMAD — November 9, 2009 @ 5:20 am | Reply


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