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Diffstat (limited to 'doc/user/ospf_fundamentals.rst')
| -rw-r--r-- | doc/user/ospf_fundamentals.rst | 34 |
1 files changed, 23 insertions, 11 deletions
diff --git a/doc/user/ospf_fundamentals.rst b/doc/user/ospf_fundamentals.rst index b0eb018107..38c18e5526 100644 --- a/doc/user/ospf_fundamentals.rst +++ b/doc/user/ospf_fundamentals.rst @@ -3,8 +3,10 @@ OSPF Fundamentals ================= -.. index:: Link-state routing protocol -.. index:: Distance-vector routing protocol +.. index:: + pair: Link-state routing protocol; OSPF + pair: Distance-vector routing protocol; OSPF + :abbr:`OSPF` is, mostly, a link-state routing protocol. In contrast to :term:`distance-vector` protocols, such as :abbr:`RIP` or :abbr:`BGP`, where @@ -12,10 +14,12 @@ routers describe available `paths` (i.e. routes) to each other, in :term:`link-state` protocols routers instead describe the state of their links to their immediate neighbouring routers. -.. index:: Link State Announcement -.. index:: Link State Advertisement -.. index:: LSA flooding -.. index:: Link State Database +.. index:: + single: Link State Announcement + single: Link State Advertisement + single: LSA flooding + single: Link State Database + Each router describes their link-state information in a message known as an :abbr:`LSA (Link State Advertisement)`, which is then propagated through to all @@ -27,7 +31,8 @@ metric, by using an algorithm such as `Edsger Dijkstra's <http://www.cs.utexas.edu/users/EWD/>`_ :abbr:`SPF (Shortest Path First)` algorithm. -.. index:: Link-state routing protocol advantages +.. index:: + pair: Link-state routing protocol; advantages By describing connectivity of a network in this way, in terms of routers and links rather than in terms of the paths through a network, @@ -39,7 +44,8 @@ reconverge on the best paths through the network. In contrast, distance vector protocols can require a progression of different path update messages from a series of different routers in order to converge. -.. index:: Link-state routing protocol disadvantages +.. index:: + pair: Link-state routing protocol; disadvantages The disadvantage to a link-state protocol is that the process of computing the best paths can be relatively intensive when compared to @@ -64,7 +70,8 @@ will nearly all be covered in greater detail further on. They may be broadly classed as: -.. index:: OSPF Hello Protocol +.. index:: + pair: Hello protocol; OSPF The Hello Protocol ^^^^^^^^^^^^^^^^^^ @@ -86,7 +93,10 @@ sharing a link, for example: The Hello protocol is comparatively trivial and will not be explored in more detail. -.. index:: OSPF LSA overview + +.. index:: + pair: LSA; OSPF + .. _ospf-lsas: LSAs @@ -120,7 +130,9 @@ OSPF defines several related mechanisms, used to manage synchronisation of :abbr:`LSDB` s between neighbours as neighbours form adjacencies and the propagation, or `flooding` of new or updated :abbr:`LSA` s. -.. index:: OSPF Areas overview + +.. index:: + pair: Area; OSPF .. _ospf-areas: |