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As the IANA allocations change, you will want to remove some of the prefix blocks<br />

from the list to override the defaults. To change the JUNOS defaults so the only martians<br />

are 0.0.0.0/8 (addresses on this network), 127.0.0.0/8 (loopback address), and<br />

240.0.0.0/4 (experimental address block, formerly the Class E addresses), configure<br />

the martian addresses to allow the remaining defaults:<br />

[edit routing-options]<br />

aviva@router1# set martians 128.0.0.0/16 orlonger allow<br />

aviva@router1# set martians 191.255.0.0/16 orlonger allow<br />

aviva@router1# set martians 192.0.0.0/24 orlonger allow<br />

aviva@router1# set martians 223.255.255.0/24 orlonger allow<br />

You can verify that these prefixes are now accepted:<br />

aviva@router1> show route martians table inet.0<br />

inet.0:<br />

0.0.0.0/0 exact -- allowed<br />

0.0.0.0/8 orlonger -- disallowed<br />

127.0.0.0/8 orlonger -- disallowed<br />

128.0.0.0/16 orlonger -- allowed<br />

191.255.0.0/16 orlonger -- allowed<br />

192.0.0.0/24 orlonger -- allowed<br />

223.255.255.0/24 orlonger -- allowed<br />

240.0.0.0/4 orlonger -- disallowed<br />

The allowed keyword in the output means that the routes are now accepted.<br />

RFC 3330, Special-Use IPv4 Addresses, describes specialized IPv4 address blocks that<br />

have been assigned to IANA to manage. Team Cymru maintains information about<br />

other prefixes that you might want to mark as martians (see http://www.cymru.com/<br />

gillsr/documents/junos-bgp-template.pdf and http://www.cymru.com/gillsr/documents/<br />

junos-martians.txt).<br />

See Also<br />

RFC 3330, Special-Use IPv4 Addresses and Team Cmyru (http://www.cymru.com/<br />

gillsr/documents/junos-bgp-template.pdf and http://www.cymru.com/gillsr/documents/<br />

junos-martians.txt)<br />

8.11 Changing Route Preferences to Migrate<br />

to Another IGP<br />

Problem<br />

You are migrating the IGP on your network from OSPF to IS-IS and you want to do<br />

this in a controlled manner.<br />

274 | Chapter 8: IP Routing<br />

This is the Title of the Book, eMatter Edition<br />

Copyright © 2008 O’Reilly & Associates, Inc. All rights reserved.

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