User`s guide

OSPF Overview
8-6 Configuring OSPF
Autonomous System External (ASE) Link Advertisements
Anautonomoussystemboundaryrouter(ASBR)advertisesexternaldestinationsthroughoutthe
OSPFautonomoussystem.Inmanycases,externallinkstatesmakeupalargepercentageofthe
linkstatesinthedatabasesofeveryrouter.Astubareaisanareainwhichyoudonotallow
advertisementsofexternalroutes,
thusreducingthesizeofthedatabaseevenmore.Instead,a
defaultsummaryroute(0.0.0.0)isinsertedintothestubareainordertoreachtheseexternal
routes.Table 8‐2liststherestrictionsassociatedwitheachtypeofarea:
Router Modes Used for OSPF Configuration
AsshownbackinTable 7‐2onpage 7‐3,theMatrixDFESeries/N‐SACLIprovidesdifferent
modesofrouteroperationforissuingasubsetofcommandsfromeachmode.Table 8‐3liststhe 
modesofoperationusedinconfiguringOSPF.Sampleconfigurationsprovidedinthischapter
willdemonstrateenablingthese
commandmodes.
Table 8-2 OSPF Area Restrictions
Area Restrictions
Normal None
Stub area No Type 5 AS-external LSA allowed
Totally Stub area No Type 3, 4 or 5 LSAs allowed except the default
summary route
NSSA No Type 5 AS-external LSAs allowed, but Type 7
LSAs that convert to Type 5 at the NSSA ABR can
traverse
NSSA Totally Stub area No Type 3, 4 or 5 LSAs except the default summary
route, but Type 7 LSAs that convert to Type 5 at the
NSSA ABR are allowed
Notes: Sample prompts shown in Table 8-3 assume module 1(or the N-SA device) has been
configured for routing, and that VLAN 1 will be designated as a outing interface.
A module designation of 1 must be entered to enable routing on the Matrix N-SA standalone device.
All other values will result in an error message.
Table 8-3 Router Modes Used for OSPF Configuration
Use this mode... To... Access method... Resulting Prompt...
Privileged EXEC
Mode
Set system operating
parameters
Show configuration
parameters
Save/copy
configurations
From the switch CLI:
1. Type router
module (using a
module number
configured for
routing).
2. Type enable.
Matrix>Router1>
Matrix>Router1#
Global
Configuration Mode
Set system-wide
parameters.
Type configure
terminal from
Privileged EXEC
mode.
Matrix>Router1(config)#