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ospf

IPv6 Routing

1. Enable IPv6 Routing To enable IPv6 routing, use: This will enable the router to send RAs unsolicited or in response to RS messages. 2. Static Routing To see the routing table, use: 3. RIP for IPv6 RIP for IPv6, aka RIPng, works just like RIPv2 for IPv4. It sends …

Routing over Frame Relay

1. Topologies 1.1 Full Mesh The simplest Frame Relay topology is the Full Mesh topology, where each router has a dedicated virtual circuit to another router. Unfortunately this design is rarely found in real life because each additional circuit costs. Of course, having so many circuits available makes it easy …

MPLS 101

1. Labels MPLS (Multi Protocol Label Switching) adds a 4 Byte header between the Layer 2 and Layer 3 header for each label. The header has 4 fields: 20 bits – Label – locally significant on the link (similar to Frame Relay DLCI) 3 bits – EXP – used for …

OSPF Mechanics

1. OSPF Router ID Each router selects an OSPF Router ID when the OSPF process starts. The Router ID is a 32 bit number, usually written in dotted decimal format. The selection process is: Manually configured Router ID Highest Loopback IP address Highest non-Loopback “up/up” IP address The interface used …

OSPF LSAs

1. LSA components Sequence number InitialSequenceNumber = 0x80000001 MaxSequenceNumber= 0x7FFFFFFF When MaxSequnceNumber is reached, and a new update must be sent, the LSA is flushed by setting the Age to MaxAge and reflooding it over all adjacencies. Then, a new version of the LSA is sent with sequence number set …

OSPF Areas

Areas are identified by a 32 bit Area ID. This can be represented as a number in decimal or in dotted decimal format. Area 0 (0.0.0.0) is reserved for backbone. The backbone is responsible for summarizing the topologies of each area to every other area => all inter-area traffic must …

OSPF 101

1. Starting the routing process OSPF can be configured inside the routing process or on the interface. Even a combination of those will be a valid option. The interface configuration will override the routing process configuration. 1.1 Inside the routing process Depending on the IOS version, when 2 network definitions …