Friday, 27 July 2012

Routing protocol Basics


Network routing protocols - IGRP, EIGRP, OSPF, ISIS, BGP
Overview
The objective of Protocols of Routing is to learn from the available routes that exist within the corporate network, build tables Routing and make decisions Routing. Some of the Protocols of Routing most common are RIP, IGRP, EIGRP, OSPF, IS-IS and BGP. There are two main types of Protocols of Routing, Although many Protocols of Routing defined with these two types. Link state and Protocols distance vector types include primary. The Protocols distance vector table to announce their Routing for all directly connected neighbors frequently at regular intervals using a large amount of bandwidth and are slow to converge. When a route is not available, all router tables must be updated with new information. The problem is that each router to announce that the new information to its neighbors, it takes a long time for all routers to present an accurate picture of the network. Distance vector protocols use subnet masks of fixed length are not scalable. The Protocols to advertise link state updates Routing only when they occur, using the bandwidth more effectively. Do not advertise routers table Routing which makes the convergence faster. The Protocol Routing flood the network with link state advertisements to all neighboring routers for each area in an attempt to network convergence with new route information. Incremental change is all that is advertised to all routers LSA as a multicast update. Use subnet masks of varying length, that are scalable and use more effectively address.
Interior Gateway Routing Protocol (IGRP)

Interior Gateway Routing Protocol is a protocol Routing distance vector developed by Cisco Systems for Protocols of Routing through multiple small and medium-sized Cisco networks. It is property that requires the use of Cisco routers. This contrasts with the IP RIP and IPX RIP, which are designed for multi-vendor networks. IGRP will route IP, IPX, AppleTalk and DECnet which makes it very versatile for different clients running Protocols. It is more scalable than RIP because it supports a number of breaks of 100, only announces every 90 seconds and uses a combination of five different values to select a destination better way. Note that since less frequently Announces IGRP uses much less bandwidth than RIP, but converges much slower, since it is 90 seconds before the IGRP routers are aware of changes in network topology. IGRP does not recognize the transfer of different autonomous systems and automatically summarized in the class boundaries of the network. There is also the option of traffic load balancing between equal or unequal cost paths metric.
Features
Distance Vector
IP routes, IPX, DECnet, Appletalk
Table Routing ad every 90 seconds
Metric: bandwidth, delay, reliability, load, MTU size
Hop Count: 100
• Fixed Length Subnet Masks
Summary on the class Web Address
Load Balancing in 6 equal or unequal cost paths (IOS 11.0)
Calculation = path metric minimum target BW * Delay (us)
Split Horizon
Timers: Invalid timer (270 sec) Flush timer (630 sec), HOLDDOWN Timer (280 seconds)
Enhanced Interior Gateway Routing Protocol (EIGRP)
Enhanced Interior Gateway Routing Protocol is a protocol Routing hybrid developed by Cisco Systems for many Protocols of Routing through a Cisco network. It has features of both Protocols of Routing distance vector and Protocols of Routing link state. It is property that requires the use of Cisco routers. Directed towards the same EIGRP Protocols routes from IGRP (IP, IPX, DECnet and AppleTalk) and use the same metrics as IGRP made to select a destination better way. There is also the option of traffic load balancing between equal or unequal cost paths metric. Summary is automatic in a class network address however, can be configured to summarize on subnet boundaries as well. Redistribution between IGRP and EIGRP is automatic too. There is no support for a number of jumps of 255 and subnet masks of varying length.
Convergence
EIGRP convergence is faster because it uses an algorithm called algorithm double or update that runs when a router detects that a particular route is not available. The router queries its neighbors in search of a viable successor. Which is defined as a neighbor with a lower cost path to a particular destination, it causes no loops Routing. EIGRP update its table Routing with the new route and the corresponding metrics. Route changes are announced only to the affected routers when changes occur. M utilizamineral bandwidth effective as the Protocols of Routing distance vector.
Autonomous Systems
EIGRP does not recognize the transfer of the various autonomous systems which are processes that run under the same domain Routing administrative. The allocation of different numbers of autonomous systems is to define a backbone as OSPF. With IGRP, and EIGRP is used to change route redistribution, filtering and summary points.
Features
Advanced Distance Vector
IP routes, IPX, DECnet, Appletalk
Of Routing Announcement: Partial When route changes
Metrics: Bandwidth, delay, reliability, load, MTU size
Hop Count: 255
Length Subnet Masks variable
Summary of the kind of network address or subnet Border
Load Balancing in 6 equal or unequal cost paths (IOS 11.0)
Timers: Active Time (180 seconds)
Calculation = path metric minimum target BW * Delay (ms) * 256
Split Horizon
LSA Multicast Address: 224.0.0.10
Open Shortest Path First (OSPF)
Open Shortest Path First is a true link state protocol developed as an open standard for Routing IP over large networks with multiple vendors. A link state protocol state advertisements sent links to all connected neighbors in the same area to communicate route information. Each OSPF enabled router, when it starts, it sends hello packets to all OSPF routers directly connected. Hello packets contain information about counters router, router ID and subnet mask. If the routers agree on the information to become OSPF neighbors. Once the routers are set adjacent neighbors by exchanging database link state. Routers from point to point and point to multipoint (as specified with the type of OSPF interface configuration) automatically establish adjacencies. OSPF routers configured as radio interfaces (Ethernet) and NBMA (Frame Relay) is used to set the designated router adjacencies.
Areas
OSPF uses a hierarchy to designated areas that are connected to a central backbone routers. Each area is defined on one or more routers that have established adjacencies. Defined OSPF backbone area 0, areas of the piece, not so stubby areas and totally stubby areas. Zone 0 is constructed with a group of routers connected in a designated office or WAN links through several offices. It is preferable to have the entire area 0 routers connected with a full mesh using an Ethernet segment at a central office. This provides a high performance and avoids the partitioning of the area should have a router connection will fail. Zone 0 is a transit zone for all traffic from adjoining areas. All traffic from the area that the route through the area first 0. Stub areas use a default route to forward traffic destined to an external network, such as EIGRP from the area border router does not send nor receive external routes. Inter-area and within the area is RoutingAs usual. Totally stubby areas are a Cisco specification that uses a default route for inter-area and external destinations. The ABR will not send or receive inter-area external or LSA. The not-so-stubby area ABR announced external routes to the type 7 LSA. External routes are not received in such area. Inter-area and within the area is RoutingAs usual. Define OSPF internal routers, backbone routers, the area border routers (ABR) and the border routers Autonomous System (ASBR). Internal routers are area-specific. Area border routers have interfaces that are assigned to more than one area as zone 0 and area 10. An autonomous system boundary router has assigned to the OSPF interfaces and protocol Routing different as OSPF or BGP. A virtual link is used when an area that has no direct connection to Zone 0. A virtual link is established between an area border router for an area that is not connected to area 0, and an area border router for an area that is connected to zone 0. Area design involves considering the geographic location of the offices and traffic flows through the company. It is important to be able to summarize the addresses of the offices of many of the area and minimize broadcast traffic.
Convergence
Rapid convergence is achieved with the SPF (Dijkstra) algorithm determines a shortest path from origin to destination. The table Routing is constructed from running SPF, which determines all routes of neighboring routers. Since each OSPF router has a copy of the database and the topology table Routing of your particular area, any changes to the route are detected faster than the Protocols distance vector and alternative routes are determined.
Designated Router
The broadcast networks such as Ethernet and non-broadcast multiple access networks such as Frame Relay is a designated router (DR) and backup designated router (BDR), which are eSelect. Designated routers establish adjacencies with all routers in that network segment. This is to reduce emissions of all regular routers send hello packets to neighbors. The DR sends multicast packets to all routers that it has established adjacencies. If the DR fails, BDR is sending multicasts to specific routers. Each router is assigned a router ID, which is the highest IP address assigned to a working interface. OSPF uses the router ID (RID) for all processes Routing.
Features
Link state
IP Routes
Of Routing Announcement: Partial When route changes
Metric: Cost compound from each destination router (100 million / speed interface)
Hop Count: None (limited by the network)
Length Subnet Masks variable
Summary of the kind of network address or subnet Border
Load Balancing through four equal cost paths
Router Types: Interior, Backbone, ABR, ASBR
Area Type: Backbone, Stubby, Not-So-Stubby, Totally Stubby
LSA Types: within the area (1.2) between the area (3,4), exterior (5.7)
Timers: Hello Interval and Dead Interval (different types of network)
LSA Multicast Address: 224.0.0.5 and 224.0.0.6 (DR / BDR) do not filter!
Interface Type: Point to Point, Broadcast, non-broadcast point-to-multipoint loopback

Integrated IS-IS

Integrated Intermediate System - Intermediate protocol Routing the system is a link state protocol like OSPF to be used with large enterprises and ISP clients. An intermediate system is a router and IS-IS protocol is Routing that routes packets between intermediate systems. IS-IS uses a database link state and runs the Dijkstra SPF algorithm to select the shortest paths routes. Routers neighbor of point to point and point to multipoint link adjacencies by sending hello packets and database exchange link state. Isis routers broadcast and NBMA networks to select a designated router establishes adjacencies with all neighboring routers of that network. The designated router and each router neighbor establish an adjacency with all neighbors routers multicast state advertisements link to the network itself. That is unlike OSPF, which sets the adjacencies between the RD and each router neighbor only. IS-IS uses a hierarchical structure of the area with the Level 1 and Level 2 types of router. Level 1 routers are similar to OSPF routers within the area, which have no direct connections outside their area. Level 2 routers include the backbone area that connects the different areas similar to OSPF area 0. IS-IS router can be an L1/L2 router, which is like an OSPF area border router (ABR), which has links to your area and the zone of the spine. The difference between IS-IS is that the links between the routers include the border of the area and not the router. Each IS-IS router must have an assigned address that is unique to a domain Routing. An address format is used which comprises an area of identification and an identification system. The area ID is the number of assigned area and the identification system is a MAC address of the router interfaces. A mask support for variable length subnet, which is standard with all Protocols link state. Note that the IS-IS process maps Routing an interface instead of a network.
Features
Link state
IP routes, CLNS
Of Routing Announcement: Partial When changes occur Routing
Metric: cost variable (default cost of 10 assigned to each interface)
Hop Count: None (limited by the network)
Length Subnet Masks variable
Summary of the kind of network address or subnet Border
Load Balancing in 6 equal cost paths
Timers: Hello Interval, Hello Multiplier
Area Types: similar to OSPF Hierarchical Topology
Router Types: Level 1 and Level 2
LSP Type: Internal L1 and L2, L2 outside
Designated Router Election, no BDR

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