EVE-NG in the Cloud

EDIT: (Feb 28, 2021) THIS IS OUTDATED CONTENT

Please see this New Video Series: https://youtube.com/playlist?list=PLGs-v2ysJb5bUwWbXFypwr2BmPonTTOER

Please see this new blog post here: https://showipintbri.github.io/blog/eve-ng-in-gcp

Everything You Need to Know About OSPF

"Everything you'll ever need to know about OSPF" is a bold statement but is goes back to "Mastering the Foundations" something I've been saying for the past 25 days. If you can master these OSPF foundations the rest is icing on the cake.

PRO-TIP: Don't treat this as a long list of items to memorize but rather a checklist of topics to lab up.

Default Behavior

• Won't start unless OSPF can determine a router-id
• Router-id determined:
1. Configured router-id
2. Highest loopback IP address
3. Highest interface IP address
• Every router within an area must have the same OSPF database
• Filtering/Summaries happen at the ABR
• Default Priority = 1, highest priority becomes the DR (where applicable)
• A Priority of "0" means router will NOT participate in DR/BDR elections.

OSPF Network Types

Broadcast

• Default for Ethernet interfaces
• Elects DR/BDR
• Uses Multicast
• Allows more than 2 routers on a link
• Timers: Hello - 10, Dead  - 40

Non-Broadcast

• Elects a DR/BDR
• Uses Unicast (neighbor statements)
• Allows more the 2 routers on a link
• Timers: Hello - 30, Dead - 120

Point-to-Point

• Default for Serial and Tunnel interfaces
• Does NOT elect DR/BDR
• Uses Multicast
• Only 2 routers allowed on a link
• Timers: Hello - 10, Dead - 40

Point-to-MultiPoint

• Does NOT elect DR/BDR
• Uses Multicast
• Allows more than 2 routers on a link
• Installs /32 host routes per neighbor
• Timers: Hello - 30, Dead - 120

Point-to-MultiPoint Non-Broadcast

• Does NOT elect DR/BDR
• Uses Unicast (neighbor statements)
• Allows more than 2 routers on a link
• Installs /32 host routes per neighbor
• Timers: Hello - 30, Dead - 120

Loopback

• Default for Loopback interfaces
• When included in OSPF, uses a /32
• To advertise with mask other-than /32, manually set network type to "point-to-point"

LSA Types

LSA Type-1: Router LSA's

• Originated from each router
• Flooded within an area
• Tells the area about all the links participating in OSPF and are associated with that area

LSA Type-2: Network LSA's

• Originated by the DR
• Only DR can originate Type-2 LSA's (If there is no DR their aren't any Type-2's)
• This LSA tells all the routers in an area about all the routers on a shared medium like Ethernet

LSA Type-3: Summary LSA's

• Originated by an ABR
• Carry the destination network prefixes from one area into another

From nonbackbone > backbone

• Connected Routes
• Intra-Area Routes

From backbone > nonbackbone

• Connected Routes
• Intra-Area Routes
• Inter-Area Routes

LSA Type-4: ASBR-Summary LSA's

• Originated by an ABR
• Tells all the other areas about the ASBR
• Tells all the other areas "to get to this Router-ID(ASBR) go through Me(ABR)!"

LSA Type-5: External LSA's

• Originated by an ASBR
• Flooded through out the OSPF domain, except into stubby areas
• Contains the Network prefix and subnet-mask for the external network

LSA Type-7: NSSA External LSA's

• Originated by ASBR
• Exist only in a Not-So-Stubby Area (NSSA)
• Are NOT flooded outside the area they were originated

Area Types

Backbone Area

• Area 0
• Act's as the HUB for all other areas
• Accepts all LSA Types

Normal Area

• All non-stub areas
• Allows LSA's Type: 1, 2, 3, 4, 5 & External Default

Stub Area

• Allows LSA Types: 1, 2, 3 & Summary Default Route ( No External Type-5's )

Totally Stubby Area

• Allows LSA Types: 1, 2 & Summary Default Route

Not-So-Stubby Area (NSSA)

• Allows LSA Types: 1, 2, 3, 7 ( No External Type-5's )
• NSSA's allow redistributing into an area but still maintain it's 'stub area' properties (not allowing External Type-5's)
• Redistributed routes are converted to Type-7 LSA's and advertised throughout the area by the ASBR
• The ABR converts Type-7 LSA's into Type-5's before advertising them into the backbone area.
• LSA Type-7's are only flooded within the area they originate

Totally Not-So-Stubby Area (NSSA)

• Allows LSA Types: 1, 2, 7 & Summary Default Route ( No External Type-5's )
• NO LSA Type-3's

Route Types

• O = Intra-area Route
• O IA = Inter-area Route (Generated by Type-3 LSA's)
• E1 = External Metric Type-1 (Generated by Type-5 LSA's)
• E2 = External Metric Type-2 (Generated by Type-5 LSA's)
• N1 = NSSA Metric Type-1
• N2 = NSSA Metric Type-2