09.12.2012 Views

Understanding the network.pdf - Back to Home

Understanding the network.pdf - Back to Home

Understanding the network.pdf - Back to Home

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

hostname ABR-a57<br />

!<br />

access-list 1 deny 10.0.0.0<br />

access-list 1 permit any<br />

!<br />

rip<br />

version 2<br />

<strong>network</strong> 172.16.0.0<br />

distribute-list 1 out E<strong>the</strong>rnet5/0<br />

distribute-list 1 out E<strong>the</strong>rnet5/1<br />

Link state pro<strong>to</strong>cols, however, can only use outbound filters for limiting <strong>the</strong> <strong>network</strong><br />

announcements being redistributed in<strong>to</strong> ano<strong>the</strong>r routing pro<strong>to</strong>col. Again, let's use<br />

Figure 10.7. In this scenario, OSPF is being used <strong>to</strong> manage all <strong>the</strong> internal routing<br />

(including <strong>the</strong> test <strong>network</strong>s) for <strong>the</strong> <strong>network</strong>. This information is <strong>the</strong>n redistributed<br />

in<strong>to</strong> BGP, which is being used <strong>to</strong> announce reachability for <strong>the</strong> <strong>network</strong> segments.<br />

However, because <strong>the</strong> test <strong>network</strong>s are using "unregistered" IP address space that<br />

cannot be announced publicly, <strong>the</strong>y need <strong>to</strong> be filtered from <strong>the</strong> redistribution. To<br />

prevent <strong>the</strong>ir announcement, <strong>the</strong>y are being suppressed using an outbound<br />

distribution list:<br />

hostname abr-a57.<br />

!<br />

router ospf 45<br />

<strong>network</strong> 172.16.192.0 0.0.0.255 area 57<br />

<strong>network</strong> 172.16.60.32 0.0.0.3 area 0.0.0.0<br />

<strong>network</strong> 172.16.60.28 0.0.0.3 area 0.0.0.0<br />

default-information originate always<br />

distribute-list 2 out bgp 23<br />

!<br />

bgp 890<br />

redistribute ospf 45<br />

neighbor 12.14.116.2 remote-as 2889<br />

neighbor 12.14.116.2 password gimmyroutes<br />

neighbor 12.14.116.2 soft-reconfiguration inbound<br />

neighbor 12.14.116.2 version 4<br />

neighbor 12.14.116.2 distribute-list 4 out<br />

neighbor 12.14.116.2 distribute-list 3 in<br />

!

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!