Sina Mirtorabi sina cisco com Agenda n What
Sina Mirtorabi ( sina @ cisco. com)
Agenda n What is Tunnel Adjacency ( TA ) ? n What does TA resolve ? n Scenarios where TA is used n How is TA established ? n How data packet are forwarded ? n TA configuration parameter
What is Tunnel Adjacency ? n TA is a new proposal in order to solve intra -area / Inter-area path preference n It is basically a generalization of VL n It can force OSPF to take a desired path n It has on-demand area partition repair
What does TA resolve ? n Intra-area / Inter-area path preference n In H&S topology, it save the cost of adding additional interface between ABRs. n On demand partition repair to avoid segmented area, required when summarization is done.
Scenarios where TA is used ( sub-optimum path)
Scenarios where TA is used ( sub-optimum path)
Scenarios where TA is used ( sharing link for different areas )
How is TA established ? n As for VL, TA is configured between two ABRs having in common an area n when there is an intra-area path through transit area, the adjacency is established announced in the area for which the TA is configured.
How data packet is forwarded ? n If ABRs have a direct link, data packet are sent without any encapsulation n If ABRs are multi-hop, data packet are encapsulated n Encapsulation is dynamic and user does not need to configure
TA configuration parameter n TA configuration parameter consists of - remote neighbor Router-ID - TA Transit Area ( TTA ) - The Area to which TA belongs n Optionally, encapsulation type and on demand partition repair
To Summarize n TA is a generalization of VL n It resolves VL limitations - TA link can belong to any area - Summarization is not affected - TA can go through Stub/NSSA n It has added value features - TA cost is configurable - TA on demand partition repair - Multiple TA through a given path
- Slides: 12