Stub Area/Network.

DANMOH009

This is my definition in the most simplest terms i can think of for a stub area/network,

Stub network/ (interface) - a interface that is not adjacent with an other OSPF routers, normally its own network seen on loopback and routers that dont connect to another ospf router.

Am i right????

i appreciate some terminology may be wrong but its how ive always remembered it.

Thanks in advance.

Ltat42a

Here's a visual to help...

MrXpert

When you're talking about stubs in OSPF you are referring to area types. A stub area in OSPF is one which suppresses LSA-5 (external routes) and replaces it with a default route. The backbone area cannot be a stub area.Stub areas are useful in OSPF when you want to reduce the size of routing tables.

On the other hand if you're referring to stubs in the other sense then that is like a hub and spoke network where the spokes are not connected to anything. Like when you see the stub of a tree left over after it was sadly chopped down. You'd use stubs in eigrp for example where you wouldn't want queries to be sent to stub routers.This saves cpu usage. Also useful if you want to prevent a router being used as a transit router.

From your definition in your post you seem to be talking about passive-interfaces. When you configure a loopback interface for example or an interface which connects to another routing domain which you don't want to form OSPF neighbors with it is a good idea to use the passive-interface cmd to prevent hellos being sent out that interface.

Christopher Dobkowski

MrXpert is right... There is a difference when it comes to stub network and stub area.

A stub network is a network where you have only one gateway from that network. So for example a network with one router that gives you access to the outer network.

Wheres stub area in OSPF is an area that does not send certain type of LSA packets. Type 5 LSAs are not permitted and type 4 are not forwarded to stub areas.

Read about LSA types... There are 12 or 11, it's out of CCNA scope, it's for CCNP more but trust me, it will clear a lot of clouds for you when it comes to OSPF

Cheers

networker050184

MrXpert I believe the OP is referring to stub vs transit networks in OSPF.

The easiest way to think of it is anything with a DR (and neighbors) is a transit network and anything without a DR is a stub network. If it can reach multiple routers out of the interface it is marked transit.

DANMOH009

Thanks too all cleared things up lots!!