What is OSPF down bit?
The down bit is a bit located in the LSA Header, and its function is to avoid loops in MPLS-VPN environments when using OSPF as PE-CE protocol. When PE2 redistributes the MP-BGP route into OSPF, it sets up the down bit, or downward, on the LSA3. So when PE3 receives that LSA3, it doesn’t take it into account.
What is capability VRF Lite?
1. ” capability vrf lite” will make OSPF process to install the routes even with DN bit set. 2. PE running VRF will set the DN bit when advertising to CE if OSPF is used for PE-CE routing.
What are the four OSPF path types?
According to section 11 of RFC 2328 , the order of preference for OSPF routes is:
- – intra-area routes, O.
- – interarea routes, O IA.
- – external routes type 1, O E1.
- – external routes type 2, O E2.
What is the router ID in OSPF?
The OSPF Router ID is used to provide a unique identity to the OSPF Router. OSPF Router ID is an IPv4 address (32-bit binary number) assigned to each router running the OSPF protocol. OSPF Router ID should not be changed after the OSPF process has been started and the ospf neighborships are established.
What is OSPF domain tag?
Domain Tag is a loop prevention mechanism, just like DN Bit. Older IOS and based on IETF original draft: LSA type 3 uses DN bit and LSA type 5 uses a Tag ( Cisco uses the name Domain Tag and the RFC uses the name Route Tag). The newer version of RFC (4577) incluses the use of DN bit for both LAS type 3 and type 5.
What is OSPF super backbone area?
The super- backbone appears as another area to the CE-routers. s. Routes redistributed into MP-BGP from OSPF will appear as inter-area routes in other OSPF sites if the original route was an intra-area or inter-area route and as external routes if the original route was an external route.
What is router ID in OSPF?
The OSPF Router ID is used to provide a unique identity to the OSPF Router. OSPF Router ID is an IPv4 address (32-bit binary number) assigned to each router running the OSPF protocol. If there is no Loopback Interfaces configured, the highest IP address on its active interfaces is selected as the OSPF Router ID.
What is OSPF domain?
On Cisco IOS, the OSPF Domain ID is the OSPF Process ID by default. The Domain ID is configurable using domain-id type value command from OSPF router configuration on the PE routers for a particular VRF instance. The Domain ID is an 8-byte quantity that is a valid BGP Extended Community Attribute.
What are the different administrative distances in OSPF?
OSPF uses three different administrative distances: intra-area, interarea, and external. Routes within an area are intra-area; routes to another area are interarea; and routes from another routing domain learned via redistribution are external. The default distance for each type of route is 110.
Can you use OSPF as a point to multipoint network?
In these cases, you can configure the OSPF network type as a point-to-multipoint network. Routing between two routers that are not directly connected will go through the router that has VCs to both routers. Note that you need not configure neighbors when using this feature.
Do you need to change OSPF interface parameters?
You are not required to alter any of these parameters, but some interface parameters must be consistent across all routers in an attached network. Those parameters are controlled by the ip ospf hello-interval, ip ospf dead-interval, and ip ospf authentication-key interface configuration commands.
Which is OSPF protocol does Cisco routers support?
OSPF also allows packet authentication and uses IP multicast when sending and receiving packets. Cisco supports RFC 1253, OSPF Version 2 Management Information Base, August 1991. The OSPF MIB defines an IP routing protocol that provides management information related to OSPF and is supported by Cisco routers.
