MPLS VPN OSPF Sham Link

In this example, four customer sites are connected to service provider MPLS backbone as depicted in the figure below. Two of the sites have direct low bandwidth link (384Kbps)for backup in case the primary links go down. This type of topology can result in suboptimal routing. The following sequence of

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MPLS VPN: Same OSPF Domain ID

On a Layer 3 MPLS VPN using OSPF as an IGP between PE and CE, OSPF domain ID is equivalent to the OSPF process ID by default. Therefore, OSPF routes are seen as OSPF inter-area (Type 3 OSPF LSA). By considering this behaviour, it is easy to distinguish real external

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OSPF Network Type – Point-to-Multipoint

Points to remember about Point-to-Multipoint OSPF network type. 1. No Designated Router (DR) and Back Designated Router(BDR) election. 2. Uses multicast to send OSPF hello. 3. Changes next-hop IP address. 4. Advertises /32 host route instead of a network route. 5. All routers in the segment must agree on the

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OSPF Network Type – Point-to-Point

Points to remember about Point-to-Point OSPF network type. 1. No Designated Router (DR) and Back Designated Router(BDR) election. 2. Uses multicast to send OSPF hello. 3. Default network type on HDLC, PPP and point-to-point NBMA. 4. Only supports adjacency of two neighbors on a segment. S0/1 .—–. 12.0.0.2/30 .—–. |

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OSPF Network Type – Non-Broadcast

Points to remember about Non-Broadcast OSPF network type. 1. Designated Router (DR) and Back Designated Router(BDR) election occurs. BDR sends LS to multicast address 224.0.0.6 which is the DR and DR sends LS to multicast address 224.0.0.5 which is all routers within the area. 2. No pre-emption meaning when the

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OSPF Network Type – Broadcast

Points to remember about Broadcast OSPF network type. 1. Designated Router (DR) and Back Designated Router(BDR) election occurs. BDR sends LS to multicast address 2240.0.6 which is the DR and DR sends LS to multicast address 224.0.0.5 which is all routers within the area. 2. No pre-emption meaning when the

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