EBGP Connections Routing

• Source the local routes for each AS at the border BGP routers

Use static routes and network statements Verify consistency of routing information

For each region/area it must carry routes to the infrastructure (all links), peering addresses and local destinations

Filter at the borders

May need to use an independent IGP process per AS

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• Divide the AS into sub-AS

eBGP between sub-AS, but some iBGP information is kept

Preserve NEXT_HOP across the sub-AS (IGP carries this information)

Preserve LOCAL_PREF and MED

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Confederations (Cont.)

• Visible to outside world as single AS

Each sub-AS uses a number from the private space

• iBGP speakers in sub-AS are fully meshed

The total number of neighbors is reduced by limiting the full mesh requirement to only the peers in the sub-AS

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Copyright © 1998, Cisco Systems, Inc. All rights reserved. Printed in USA. 0901_04F9_c3.scr


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