[permalink] [id link]
An OSPF network may be structured, or subdivided, into routing areas to simplify administration and optimize traffic and resource utilization.
from
Wikipedia
Some Related Sentences
OSPF and network
PNNI uses the same shortest-path-first algorithm used by OSPF and IS-IS to route IP packets to share topology information between switches and select a route through a network.
Like the OSPF protocol, IS-IS uses Dijkstra's algorithm for computing the best path through the network.
Both IS-IS and OSPF are link state protocols, and both use the same Dijkstra algorithm for computing the best path through the network.
While OSPF is natively built to route IP and is itself a Layer 3 protocol that runs on top of IP, IS-IS is natively an OSI network layer protocol ( it is at the same layer as CLNS ).
IS-IS also differs from OSPF in the methods by which it reliably floods topology and topology change information through the network.
By convention, area 0 ( zero ) or < tt > 0. 0. 0. 0 </ tt > represents the core or backbone region of an OSPF network.
OSPF uses multicast addressing for route flooding on a broadcast network link.
The backbone area ( also known as area 0 or area 0. 0. 0. 0 ) forms the core of an OSPF network.
A transit area is an area with two or more OSPF border routers and is used to pass network traffic from one adjacent area to another.
OSPF uses path cost as its basic routing metric, which was defined by the standard not to equate to any standard value such as speed, so the network designer could pick a metric important to the design.
In most current networking environments, RIP is not the preferred choice for routing as its time to converge and scalability are poor compared to EIGRP, OSPF, or IS-IS ( the latter two being link-state routing protocols ), and ( without RMTI ) a hop limit severely limits the size of network it can be used in.
As a result, the shortest path first is widely used in network routing protocols, most notably IS-IS and OSPF ( Open Shortest Path First ).
The protocol establishes a framework between network routers in order to achieve default gateway failover if the primary gateway becomes inaccessible, in close association with a rapid-converging routing protocol like EIGRP or OSPF.
Since link-state routing requires the topology database to be synchronized across the network, OSPF and IS-IS perform topology flooding using a reliable algorithm.
Long before anoNet reaches that number of routers the network will have to be split into OSPF clouds, or switched to a completely different routing protocol or alter the BGP protocol to use a 32bit integer for ASNs, like the rest of the Internet will do, since 32-bit AS numbers now are standardised.
Raw sockets are typically available in network equipment, and used for routing protocols such as the Internet Group Management Protocol ( IGMP ) and Open Shortest Path First ( OSPF ), and in the Internet Control Message Protocol ( ICMP, best known for the ping suboperation ).
In a network injection attack, a cracker can make use of access points that are exposed to non-filtered network traffic, specifically broadcasting network traffic such as “ Spanning Tree ” ( 802. 1D ), OSPF, RIP, and HSRP.
OSPF and may
A given physical router may have one or more OSPF processes.
Protocols that support some form of adjacency setup, such as OSPF or IS-IS, may also be used to bootstrap a BFD session.
OSPF and be
An example would be the joining of a number of large OSPF ( Open Shortest Path First ) networks where OSPF by itself would not scale to size.
Several vendors ( Cisco, Juniper, Alcatel-Lucent, Huawei, Quagga ), now implement the below two extensions to stub and NSSA area and although not covered by RFC they are considered by many to be standard features in OSPF implementations.
This identifier must be established in every OSPF instance.
To many, it is not clear whether a whole new protocol is needed, or whether OSPF could be extended with support for wireless interfaces.
A lower numerical value is preferred, e. g. an OSPF route with an administrative distance of 110 will be chosen over a RIP route with an administrative distance of 120.
They present a means of detecting false packets, at least to the subnet, by essentially making use of existing OSPF routing state to have routers make intelligent decisions about whether or not a packet should be routed.
While the papers describing HSLS do not focus on security, techniques such as digital signatures on routing updates can be used with HSLS ( similar to OSPF with Digital Signatures ), and BBN has implemented HSLS with digital signatures on neighbor discovery messages and link state updates.
OSPF and into
An OSPF domain is divided into areas that are labeled with 32-bit area identifiers.
An NSSA ASBR generates this LSA, and an NSSA ABR router translates it into type 5 LSA which gets propagated into the OSPF domain.
In such a case, the ASBR does send externals into the totally stubby area, and they are available to OSPF speakers within that area.
OSPF and routing
Dijkstra's algorithm is used in SPF, Shortest Path First, which is used in the routing protocols OSPF and IS-IS.
Interior routing mostly uses link-state routing protocols such as OSPF and IS-IS.
Open Shortest Path First ( OSPF ) is an adaptive routing protocol for Internet Protocol ( IP ) networks.
OSPF is an interior gateway protocol that routes Internet Protocol ( IP ) packets solely within a single routing domain ( autonomous system ).
OSPF detects changes in the topology, such as link failures, very quickly and converges on a new loop-free routing structure within seconds.
The OSPF routing policies to construct a route table are governed by link cost factors ( external metrics ) associated with each routing interface.
For routing multicast IP traffic, OSPF supports the Multicast Open Shortest Path First protocol ( MOSPF ) as defined in RFC 1584.
The OSPF protocol, when running on IPv4, can operate securely between routers, optionally using a variety of authentication methods to allow only trusted routers to participate in routing.
As a link state routing protocol, OSPF establishes and maintains neighbor relationships in order to exchange routing updates with other routers.
RFC 3717 documents work in optical routing for IP, based on " constraint-based " extensions to OSPF and IS-IS.
These avoid loop formation in all cases, but suffer from increased complexity, and their deployment has been slowed down by the success of link-state routing protocols such as OSPF.
Examples of link-state routing protocols include OSPF and IS-IS.
The technique was later adapted for use in the contemporary link-state routing protocols IS-IS and OSPF.
However, it does synchronize routing tables at start up as OSPF does, and sends specific updates only when topology changes occur.
* A OSPF totally stubby area is one which only has a default route to the rest of the OSPF routing domain.
Other routing protocols such as Open Shortest Path First ( OSPF ) and Enhanced Interior Gateway Routing Protocol ( EIGRP ) only send updates when a connection changes.
0.453 seconds.