The only protocols which redistribute one another automatically are E-IGRP
and IGRP when both are configured with the same autonomous system number.
The reason for this is that E-IGRP uses a 32-bit field for the metric and
IGRP uses a 24-bit field, allowing the router to use a multiplier of 256 to
convert automatically from IGRP to E-IGRP and dividing by 256 to go the
other way.
However, in the majority of cases, route redistribution must be manually
configured and requires an arbitrary decision on the part of the
administrator as to the conversion between dissimilar metrics. Thus, for
example, when going from RIP into some other routing protocol, one must
convert from hop count to the appropriate new metric.
Therefore it follows that you must configure the router to use the correct
conversion metric when importing routes from one into another protocol.
Certain protocols only require one parameter, such as RIP and OSPF, both of
which require either a hop count (RIP) or bandwidth (OSPF). E-IGRP and IGRP,
however, base their metric calculation on an entirely different equation, so
you as the administrator have to input the values to be used by the routing
algorithms of these protocols, supplying the bandwidth, delay, loading,
reliability and MTU sizes.
You must configure these metric values for the protocol into which you are
redistributing (importing) routes from another source, be that static or
dynamic. In other words, were you bringing in RIP routes into an OSPF AS,
you would configure the redistribution under OSPF.
Hope this clears it up!
--
Edward Solomon
CCNA, CCSI (ICND, BSCN)
Senior I/T Specialist
Networking Solutions
IBM Canada Ltd. - Learning Services
Tel.: (905) 316-3241 Fax: (905) 316-3101
E-mail: [EMAIL PROTECTED]
Internet: http://www.can.ibm.com/services/learning/net_internet.html
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