Ospf - Zte ZXR10 GER User Manual

ZXR10 GER (V2.6.03) General Excellent Router User Manual Volume-I
OSPF Basics
OSPF Features
OSPF Network
Type
Hello Packets
and Timers
186 Confidential and Proprietary Information of ZTE CORPORATION

OSPF

Open Shortest Path First (OSPF) protocol is one of the most
popular and widely used routing protocols. OSPF is a link state
protocol, which has overcome the disadvantages of RIP and
other distance vector protocols. OSPF is also an open standard,
and different types of equipment from multiple manufacturers
can implement protocol interconnection.
OSPF version 1 is defined in RFC1131. At present, OSPF version
2 is used, which is defined in RFC2328. ZXR10 GER supports
OSPF of version 2 completely.
Fast convergence:
synchronization
synchronously by means of fast flooding of link state update.
No route loop: Shortest Path First (SPF) algorithm is applied
to guarantee that no loops will be generated.
Route aggregation: Reduces the size of the routing table.
Classless routing completely: supporting Variable Length
Subnet Mask (VLSM) and Classless Inter-Domain Routing
(CIDR).
Reduction of network bandwidth: Since triggered update
mechanism is used, the update information will be sent only
when the network changes.
Support interface packet authentication to guarantee the
security of routing calculation
Sending update in multicast mode: Reduces interferences
upon unrelated network equipment while plays the broadcast
role at the same time.
A network type that is connected to an interface is used to
judge the default OSPF behavior on interface. The network
type affects the adjacency formation and method in which a
router assigns timers to the interface.
OSPF covers the following five network types:
Broadcast network
Non-broadcast Multi-access (NBMA) network
Point-to-point network
Point-to-multipoint network
Virtual links
OSPF routers exchange Hello packets at a certain interval to
keep alive status among neighbors. Hello packets can find OSPF
neighbors, set up association and adjacency among neighbors
and select designated routers. Among the three network types
(that is, broadcast network, point-to-point network and point-to-
multi-point network), Hello packets are multicast packets.
OSPF guarantees
and also calculates
database
routing table