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Avocent Access Router Cyclades-PR2000 User Manual

Page 82

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Cyclades-PR2000

Chapter 9 - Routing Protocols

82

STEP FOUR
An access list needs at least one rule. The example in Figure 9.6 shows three access lists, each one with several
rules. Each neighbor can be assigned up to 6 access lists, as seen in step 2.

Route Map

Discarded

Routes

Discarded

Routes

Discarded

Routes

Seq.

4

Seq.

10

Access list

popeye_comm

type Community

Access list

popeye_dist

type Distribution

Access list

popeye_path

type AS Path

BGP-4

Message From

Tele Popeye

Seq.

2

Rule

2

Rule

2

Rule

0

Rule

0

Rule

0

Rule

1

Rule

1

Rule

1

FIGURE 9.6 UPDATE MESSAGE ARRIVING FROM TELE POPEYE PASSING THROUGH 3 FILTERS AND A

ROUTE MAP

An update message arriving from the neighbor called Popeye in step 2 will pass through the filters assigned to it
in the Neighbor Menu. The figure shows the case where the scope of the list is permit and that of the rules is deny.
Each rule causes routes to be discarded until finally the shortened message arrives at the route map (if one has
been configured for this neighbor).