Network Layer Jobs IP Routing One of the main roles of the Network layer is to forward packets between hosts. A host can send a packet to: Itself: Host can use it’s own interface IP or its loopback address to send a packet to itself. Same local network: When a host wants to send a […]
In this article we are going to talk about different variation of SPF (Shortest Path First). Dijkstra’s SPF is the algorithm that Link State Routing Protocols such as OSPF and IS-IS are using. It has many variations which we will cover them here: CSPF (Constraint Based SPF) CSPF is being used in Traffic Engineering Dynamic […]
IS-IS Overview Intermediate system to intermediate system (Short for IS-IS) is an IGP link-state protocol which builds a link-state database. Like OSPF, It will the run the Dijkstra SPF algorithm to find the best path to the destination. IS-IS has an AD of 115 with Cisco NX-OS. Unlike OSPF, IS-IS does not run over network […]
BGP Overview Border-Gateway Protocol (BGP) is an extremely scalable routing protocol which gives you a lot of control to choose the best route. It is a path-vector, which unlike OSPF where routers individually run SPF algorithm on their Link-State Database, it advertises the routes to the network. BGP connects two autonomous systems (AS) to teach […]
OSPFv2 Overview With Open-Shortest Path First (OSPF) as a Link-State routing protocol, routers build some information about the network. Those information include: Router ID Number of Links Links Descriptions Attached Router Subnet Mask Metric The routers multicast these information (Link State Advertisement or LSA) to the segment. As a result, all routers in the same […]
STP Features In this section we will discuss on different improvement which added to the Rapid spanning-tree. In particular we talk about: Convergence Optimization Edge Port STP Filters BPDU Filter BPDU Guard Root Guard Unidirectional Link Detection Loop Guard Bridge Assurance Convergence Optimization Spanning-Tree Edge Port This is equivalent of PortFast feature with Common Spanning-Tree. […]
Audiences: Candidates who want to prepare for CCIE Data Center (v3.0) Introduction to NX-OS Command Line In this section, we assume that you know how to connect to a NX-OS CLI via a terminal emulator program. Here is how we bootstrap our Nexus switch for the first time. If you skip Power On Auto Provisioning, […]
A Brief Introduction to MST IEEE 802.1s originally started as Cisco’s Multiple Instances Spanning Tree Protocol (MISTP). Remember that RapidPVST+ each VLAN is mapped to a single spanning tree instance. When you have 200 VLANs, it means there are 200 instances of spanning tree. This requires a lot of CPU power and memory. You can […]
A Brief Evolution of Spanning-Tree Protocols on NX-OS Before discussing on IEEE 802.1w, I would want to present a brief history of Spanning-tree evolution, the we continue with our main subject of this post. Spanning-tree is the loop prevention mechanism in Layer-2. According to graph theory: Spanning: A spanning graph is a subgraph obtained by […]
Audiences: Candidates who want to prepare for CCIE Data Center (v3.0) Scope: 1.1.b Tagging/Trunking from CCIE Data Center (v3.0) Exam Topics – Practical Exam Inter-VLAN Routing Although we can route between two VLANs with a router 802.1Q trunk (Router-On-A-Stick AKA ROAS), but that is not in the scope of our CCIE Data Center curriculum; instead, […]
Elissa Garlin
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