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Flashcards in IP Routing Deck (51)
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What is a router on a stick consisted of

A layer 2 switch which cannot route information with separate vlans out of different ports, so it is connected to a router via a trunk port to be able to route between vlans


What is a SVI & routed port

With a layer 3 switch, you have a virtual interface (with ip address) for each VLAN, which represents all ports that belong to the VLAN so internal routing is possible, OR if you want a routed port, you assign a port on the switch to a router port and connect the switch to a router (assign an IP to the port)


What does SVI stand for

Switch Virtual Interface


What does OSPF stand for

Open shortest path first


What versions of OSPF are for IPv4 and IPv6

OSPFv2 only covers IPv4 while OSPFv3 covers IPv6


What is OSPF's Admin Distance



What type of routing protocol is OSPF

Link State


What is characteristic of OSPF

Establishes adjacencies with other routers by sending Link State Advertisements to routers in an area, Constructs a link state database from link state advertisements


What does OSPF find the best path based on?

Cost, which is a function of bandwidth


How does a router send a packet down the right path

It attempts to inject the best path into an IP routing table (populates routing information table) to be injected into IP table


What is a neighbor

A neighbor is a router that reside on the same network link, exchange hello messages with one another BUT NOT NECESSARY Link State Advertisements


What is an adjacency

An adjacency are routers that are neighbors, have exchanged Link State Updates and Data Description Packets; Only adjacencies construct a link state database


What does each OSPF topology have?

Area 0, a backbone area, or


What's the requirement for having multiple areas in the OSPF model?

Each non-backbone area should connect to the backbone area.


What are routers with interfaces in more than one area called

Area Border Router (ABR)


What is one way that Cisco does not recommend but can allow you to directly connect any non-backbone area to a backbone area

Establish a virtual link between the two areas



Establish a virtual link between the two Area Border Routers


How do you calculate cost of an OSPF route?

Cost = reference bandwidth / interface bandwidth


What is the default reference bandwidth?

100 Mbps


What happens if your OSPF cost is a decimal?

You round up to the next nearest number


What is the command to set a higher reference bandwidth for OSPF

auto-cost reference-bandwidth value


What's the solution to not having a full adjacency for all routers in a network

Elect a DR and a BDR


What are the addresses for OSPF config for All OSPF router multicast and for All designated routers (top 2) FF02::5 and FF02::6 for IPv6 respectively


How is a DR elected?

DR election goes first then BDR, router with highest OSPF priority wins 0 = don't run 1 = default up to 255 (can be statically set), Router with highest id becomes DR if that's not enough (highest IP of router loopback or non-loopback = router id)


What does it mean that DR system is non-preemptive

If you add a router with a higher ID and OSPF priority to an existing configuration, the new router will not become the DR


Tell me about a OSPF Broadcast network (DR, Default Hello Interval, static neighbors?)

Will elect a DR and BDR, Default Hello Interval of 10 sec, Can use multicast to dynamically discover neighbors (ie 6 routers connected to a broadcast median such as a switch)


Tell me about a Point To Point Network

A Router connected to another router over a WAN
No need to elect a DR and BDR as there's only one other router to discover, Default Hello 10 sec, Can discover other router so no need for static assignment


Tell me about a Non-Broadcast (NBMA)

Elects a DR& sometimes BDR but you have to make sure the DR is openly adjacent to the rest of the routers
Statically configure neighbors
Hello Interval is 30 seconds


Tell me about a point to multipoint network

Topologically looks like a non-broadcast type with a router connected to frame relay and 3 other routers connected via WAN
No DR and BDR needed since each dashed line is a point to point connection Hello Interval of 30 seconds no need for static neighbors


What is the default OSPF type for ethernet networks