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* An OSPF stubby area is one which receives routes from other areas in the OSPF domain but for external routes, which are communicated via a Type 5 Link-state advertisement, the stubby area is only aware of a default route
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Some Related Sentences
OSPF and stubby
In such a case, the ASBR does send externals into the totally stubby area, and they are available to OSPF speakers within that area.
* A OSPF totally stubby area is one which only has a default route to the rest of the OSPF routing domain.
OSPF and area
In OSPF, areas are delineated on the interface such that an area border router ( ABR ) is actually in two or more areas at once, effectively creating the borders between areas inside the ABR, whereas in IS-IS area borders are in between routers, designated as Level 2 or Level 1-2.
Given the same set of resources, IS-IS can support more routers in an area than OSPF.
By convention, area 0 ( zero ) or < tt > 0. 0. 0. 0 </ tt > represents the core or backbone region of an OSPF network.
Each additional area must have a direct or virtual connection to the backbone OSPF area.
An OSPF domain is divided into areas that are labeled with 32-bit area identifiers.
The area identifiers for IPv6 implementations of OSPF ( OSPFv3 ) also use 32-bit identifiers written in the same notation.
While most OSPF implementations will right-justify an area number written in a format other than dotted decimal format ( e. g., area 1 ), it is wise to always use dotted-decimal formats.
The backbone area ( also known as area 0 or area 0. 0. 0. 0 ) forms the core of an OSPF network.
All OSPF areas must connect to the backbone area.
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.
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.
An internal router is a router that has OSPF neighbor relationships with interfaces in the same area.
Backbone routers are all routers that are connected to the OSPF backbone, irrespective of whether they are also area border routers or internal routers of the backbone area.
OSPF and is
Dijkstra's algorithm is used in SPF, Shortest Path First, which is used in the routing protocols OSPF and IS-IS.
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 ).
The logical view is that OSPF creates something of a spider web or star topology of many areas all attached directly to Area Zero and IS-IS by contrast creates a logical topology of a backbone of Level 2 routers with branches of Level 1-2 and Level 1 routers forming the individual areas.
Open Shortest Path First ( OSPF ) is an adaptive routing protocol for Internet Protocol ( IP ) networks.
It is defined as OSPF Version 2 in RFC 2328 ( 1998 ) for IPv4.
OSPF is perhaps the most widely used interior gateway protocol ( IGP ) in large enterprise networks.
OSPF is an interior gateway protocol that routes Internet Protocol ( IP ) packets solely within a single routing domain ( autonomous system ).
OSPF does not use a TCP / IP transport protocol ( UDP, TCP ), but is encapsulated directly in IP datagrams with protocol number 89.
PIM ( Protocol Independent Multicast ) in conjunction with OSPF or other IGPs, ( Interior Gateway Protocol ), is widely deployed.
The neighbor relationship table is called an adjacency database in OSPF.
Provided that OSPF is configured correctly, OSPF forms neighbor relationships only with the routers directly connected to it.
It is the logical and physical structure for the ' OSPF domain ' and is attached to all nonzero areas in the OSPF domain.
Note that in OSPF the term Autonomous System Boundary Router ( ASBR ) is historic, in the sense that many OSPF domains can coexist in the same Internet-visible autonomous system, RFC1996.
OSPF and one
OSPF multicast IP packets never traverse IP routers, they never travel more than one hop.
A given physical router may have one or more OSPF processes.
One version of RIP served as one of the initial so-called interior gateway protocols for the growing Internet, before the arrival of the more modern OSPF and IS-IS.
OSPF and which
IS-IS also differs from OSPF in the methods by which it reliably floods topology and topology change information through the network.
An NSSA ASBR generates this LSA, and an NSSA ABR router translates it into type 5 LSA which gets propagated into the OSPF domain.
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.
* For each interface on which no DR has been elected, OSPF refers to these subnets as stub networks.
OSPF and from
IS-IS differs from OSPF in the way that " areas " are defined and routed between.
The " Main OSPF Packet Header " is the same for all 5 types of packets ( with exception of the Type field ) whereas the following sub-headers will vary from type to type and are shown below the Main OSPF Packet Header.
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.
However, protocols like OSPF will propagate a link state update from the failed nodes neighbors, and thus all nodes will learn quickly of the failed node's demise ( or disconnection ).
OSPF and other
OSPF, on the other hand, was designed for IPv4.
As a link state routing protocol, OSPF establishes and maintains neighbor relationships in order to exchange routing updates with other routers.
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