Multi-Area OSPF on IOS XR
-
Upload
codergenie-technologies -
Category
Technology
-
view
182 -
download
3
Transcript of Multi-Area OSPF on IOS XR
![Page 1: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/1.jpg)
MULTI-AREA OSPFV2 ON
IOS XRBy Aladdin
CCIE Service Provider & Security
CoderGenie Technologies
![Page 2: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/2.jpg)
AGENDA
OSPF Packet Types
OSPF LSA Types
OSFP Router and Area Types
Demonstration
![Page 3: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/3.jpg)
OSPF OPERATION
Establishing Router Adjacencies
Electing DR and BDR
Discovering Routes
Choosing Routes
Maintaining Routing information
![Page 4: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/4.jpg)
OSPF PACKET HEADER
![Page 5: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/5.jpg)
OSPF PACKET TYPES
![Page 6: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/6.jpg)
OSPF STATES
![Page 7: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/7.jpg)
OSPF STATES
![Page 8: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/8.jpg)
OSPF STATES
![Page 9: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/9.jpg)
OSPF HIERARCHICAL ROUTING OSPF requires hierarchical network
design through configuring areas where
every router must belong to at least one
area and every OSPF network must have
an area 0.
Area 0 is our Transit (backbone) area.
Any other area is called regular (non
backbone) area. All regular areas must
touch area 0 except a few exceptions.
Areas minimize the impact of network
events within an area and help scale the
size of the network through various area
types (stub, nssa etc) and route
summarization.
![Page 10: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/10.jpg)
OSPF ROUTER TYPES Internal: All interfaces within the
same area.
Backbone: At least one interface
in area 0.
Area Border (ABR): Interfaces in
different areas.
Autonomous System Boundary
Router (ASBR): one interface
connected to external network.
![Page 11: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/11.jpg)
LSA TYPES
![Page 12: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/12.jpg)
LSA TYPE 1: ROUTER LSA One router LSA (type 1) for
every router in an area
Includes list of directly
attached links
Each link identified by IP
prefix assigned to link and
link type
Identified by the router ID of
the originating router
Floods within its area only; does
not cross ABR
![Page 13: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/13.jpg)
LSA TYPE 2: NETWORK LSA One network (type 2) LSA for
each transit broadcast or
NBMA network in
an area
Includes list of attached
routers on the transit link
Includes subnet mask of link
Advertised by the DR of the
broadcast network
Floods within its area only; does
not cross ABR
![Page 14: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/14.jpg)
LSA TYPE 3: SUMMARY LSA Type 3 LSAs are used to flood
network information to areas outside the originating area (interarea)
Describes network number and mask of link.
Advertised by the ABR of originating area.
Regenerated by subsequent ABRs to flood throughout the autonomous system.
By default, routes are not summarized, and type 3 LSA is advertised for every subnet.
![Page 15: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/15.jpg)
LSA TYPE 4: ASBR SUMMARY LSASummary (type 4) LSAs are used
to advertise an ASBR to all other areas in the autonomous system.
They are generated by the ABR of the originating area.
They are regenerated by all subsequent ABRs to flood throughout the autonomous system.
Type 4 LSAs contain the router ID of the ASBR.
![Page 16: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/16.jpg)
LSA TYPE 5: EXTERNAL LSAExternal (type 5) LSAs are used to
advertise networks from other autonomous systems.
Type 5 LSAs are advertised and owned by the originating ASBR.
Type 5 LSAs flood throughout the entire autonomous system.
The advertising router ID (ASBR) is unchanged throughout the autonomous system.
Type 4 LSA is needed to find the ASBR.
By default, routes are not summarized.
![Page 17: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/17.jpg)
AREA TYPESStub Area – as per Cisco Doc
“A stub area is an area that does not accept route advertisements or detailed network information external to the area. Area 0 cannot be a stub area.”
Not So Stubby Area – as per Cisco Doc
“NSSA does not flood Type 5 external LSAs from the core into the area, but can import autonomous system external routes in a limited fashion within the area. Area 0 cannot be an NSSA.”
![Page 18: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/18.jpg)
STUB AREA ON IOS XRDefault route is advertised into stub
area by the ABR1 with a default cost of 1.
RP/0/RP0/CPU0:ABR1(config)# router ospf 1
RP/0/RP0/CPU0:ABR1(config-ospf)# area 50
RP/0/RP0/CPU0:ABR1(config-ospf-ar)# stub
RP/0/RP0/CPU0:ABR1(config-ospf-ar)#default-cost 15
no-summary keyword prevents the ABR from sending summary link-state advertisements (Type 3) in the stub area making a “totally” stubby area. default-cost specifies a cost for the default summary route sent into stub area.
![Page 19: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/19.jpg)
NOT-SO-STUBBY AREA ON IOS XR
Default route is advertised into stub area by the ABR1 with a default cost of 1.
RP/0/RP0/CPU0:ABR1(config)# router ospf 1
RP/0/RP0/CPU0:ABR1(config-ospf)# area 50
RP/0/RP0/CPU0:ABR1(config-ospf-ar)# nssa
RP/0/RP0/CPU0:ABR1(config-ospf-ar)#default-cost 15
no-summary keyword prevents the ABR from sending summary link-state advertisements (Type 3) in the not-so-stubby area making a “totally” not-so-stubby area. default-cost specifies a cost for the default summary route sent into an NSSA.
![Page 20: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/20.jpg)
DEMO
![Page 21: Multi-Area OSPF on IOS XR](https://reader033.fdocuments.in/reader033/viewer/2022052213/55a99eaa1a28aba05b8b46eb/html5/thumbnails/21.jpg)
“
”
CODERGENIE TECHNOLOGIES
HTTP://WWW.CODERGENIE.COM/TRAININGS
http://blog.codergenie.com
http://certification.codergenie.com