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OSPF-HCIP-HUAWEI Cheat Sheet (DRAFT) by

All you need to Know about OSPF for the HCIP DATACOM CORE Certification

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Common LSA Types

Router-LSA Type 1
Every router on an OSPF network generates Router­-LSAs. A Router-LSA describes a router's link state and cost and can be flooded only in the area to which the interface belongs.
Networ­k-LSA Type 2
A designated router (DR) generates Networ­k-LSAs. A Networ­k-LSA describes all the routers that establish adjace­ncies with the DR on the MA network to which the DR is connected and the DR itself. The LSA can be flooded only in the area to which the interface belongs.
Networ­k-s­umm­ary-LSA Type 3
An area border router (ABR) generates Networ­k-s­umm­ary­-LSAs. A Networ­k-s­umm­ary-LSA describes the route to the destin­ation network segment of an area. It is used to transmit inter-area routes.
ASBR-s­umm­ary-LSA Type 4
An ABR generates ASBR-s­umm­ary­-LSAs. An ASBR-s­umm­ary-LSA describes routes to an ASBR, and is equivalent to a host route to an autonomous system border router (ASBR).
AS-ext­ern­al-LSA Type 5
An ASBR generates AS-ext­ern­al-­LSAs. An AS-ext­ern­al-LSA describes routes to destin­ations outside an AS
NSSA LSA Type 7
An ASBR generates NSSA LSAs. An NSSA LSA describes routes to destin­ations outside an AS. NSSA LSAs have similar functions as AS-ext­ern­al-­LSAs, but are flooded in different areas. NSSA LSAs can be flooded only in the NSSA and cannot enter area 0. The ABR in the NSSA converts Type 7 LSAs into Type 5 LSAs and injects them into area 0.

DR/BDR­/DR­other

DR and BDR election process on a Broadcast or NBMA link:

1 The interface with the higher PSPF DR priority becomes the DR
2 If the priority (default 1) are is the same the router interface with the HIGHER OSPF router ID is elected as the DR.
3 If a DR and BDR existe on the network, newly connected routers will accept the DR and BDR that existe regardless of its router ID or priority.
4 IF the DR fails and goes Down, the BDR takes over the role of the DR and the remaing devices whose priority is greater than 0 compete to become the new BDR.


Only the DR and BDR can stablish adjace­ncies with other OSFP routers. DRothers do not stablish OSPF adjace­ncies with one another and their relati­onshiot is in the 2-way state
 

Link State Procol Steps

5 Establish a neighbor relati­onship between neighb­oring routers.
6 Exchange link state inform­acion.
7 Calculate optimal path.
8 Generate routing entries according to the shortest path tree and load the routin entries to the routing table.
 

Attributes

Type
Link-State
Algorithm
Dijkstra
Metric
Cost
Route Preference Intern­al/­Ext­ernal
10/150
Protoc­ols­/Port
IP/89
Hello Multicast Address
224.0.0.5
DR Multicast Address
224.0.0.6

Formula

Cost
100M/I­nte­rface bandwidth

FSM

1 Down
2 Init
3 2-way
4 Extart
5 Exchange
6 Full