diff --git a/src/3-ip-connectivity.md b/src/3-ip-connectivity.md new file mode 100644 index 0000000..7edecfb --- /dev/null +++ b/src/3-ip-connectivity.md @@ -0,0 +1,51 @@ +# IP Connectivity + +This section covers IP routing concepts, including routing tables, static routing, dynamic routing with OSPFv2, and first-hop redundancy protocols. + +## 3.1 Routing Tables + +A routing table stores information that routers use to make forwarding decisions. Key components include: + +* **Routing Protocol Code:** Indicates the protocol used to learn the route (e.g., O, S, D for OSPF, static, and EIGRP respectively). +* **Prefix:** The network address of the destination network. +* **Network Mask:** Indicates which bits of the address identify the network and which identify the host. +* **Next Hop:** The IP address of the next router to which the packet should be forwarded. +* **Administrative Distance:** A measure of the trustworthiness of a routing source. Lower values are more trusted. +* **Metric:** A value used by routing protocols to determine the best path to a destination. +* **Gateway of Last Resort:** The default route used when no specific route is found for a destination. + +## 3.2 Router Forwarding Decisions + +Routers use the following criteria to make forwarding decisions: + +* **Longest Prefix Match:** The route with the most specific (longest) match to the destination address is preferred. +* **Administrative Distance:** If multiple routes with the same prefix length exist, the route with the lower administrative distance is preferred. +* **Routing Protocol Metric:** If multiple routes have the same prefix length and administrative distance, the route with the lowest metric is preferred. + +## 3.3 IPv4 and IPv6 Static Routing + +Static routes are manually configured routes. Types of static routes include: + +* **Default Route:** A route that matches any destination and sends traffic to a specified next hop. +* **Network Route:** A route to a specific network. +* **Host Route:** A route to a specific host. +* **Floating Static Route:** A backup route that is used only if the primary route fails. It has a higher administrative distance than the primary route. + +## 3.4 Single Area OSPFv2 + +OSPF (Open Shortest Path First) is a link-state dynamic routing protocol. + +* **Neighbor Adjacencies:** OSPF routers form neighbor relationships with other OSPF routers on the same network. +* **Point-to-Point:** OSPF configuration for point-to-point links. +* **Broadcast:** OSPF configuration for broadcast networks. + * **DR (Designated Router):** Elected on a broadcast network to reduce the number of OSPF adjacencies. + * **BDR (Backup Designated Router):** Takes over if the DR fails. +* **Router ID:** A unique identifier for an OSPF router. + +## 3.5 First Hop Redundancy Protocols + +First Hop Redundancy Protocols (FHRPs) provide gateway redundancy for end devices. They allow multiple routers to share a virtual IP address, and if one router fails, another takes over. Examples include: + +* **Hot Standby Router Protocol (HSRP):** Cisco proprietary protocol. +* **Virtual Router Redundancy Protocol (VRRP):** An open standard protocol. +* **Gateway Load Balancing Protocol (GLBP):** Cisco proprietary protocol that allows load sharing between multiple routers. \ No newline at end of file diff --git a/src/SUMMARY.md b/src/SUMMARY.md index d19c89c..d816013 100644 --- a/src/SUMMARY.md +++ b/src/SUMMARY.md @@ -2,3 +2,4 @@ - [Chapter 1 Network Fundamentals](1-network-fundamentals.md) - [Chapter 2 Network Access](2-network-access.md) +- [Chapter 3 IP Connectivity](3-ip-connectivity.md)