BGP

Question 1

What type of routing protocol is BGP

Answer 1

Path Vector

Question 2

eBGP AD

Answer 2

20

Question 3

IBGP AD

Answer 3

200

Question 4

BGP protocol

Answer 4

IP

Question 5

BGP transport

Answer 5

TCP 179

Question 6

BGP authentication

Answer 6

md5

Question 7

What is an BGP AS

Answer 7

Autonomous System

Question 8

What is an Autonoumous System

Answer 8

A logical domain under the control of a single entity

Question 9

What is External BGP

Answer 9

BGP adjacencies that span AS boundries

Question 10

What is Internal BGP

Answer 10

BGP adjacendies formed within a single AS

Question 11

What is the “BGP Synchronization” requirement

Answer 11

A route must be known by an IGP before it will be advertised to BGP peers

Question 12

Four BGP packet types (O,U,K,N)

Answer 12

Open, Update, Keepalive, Notification

Question 13

BGP Neighbor states (I,A,C,OS,OC,E)

Answer 13

Idle, Active, Connect, Open Sent, Open Confirm, Established

Question 14

BGP neighbor state: Idle

Answer 14

Neighbor is not responding

Question 15

BGP neighbor state: Active

Answer 15

Attempting to connect

Question 16

BGP neighbor state: Connect

Answer 16

TCP session established

Question 17

BGP neighbor state: Open Sent

Answer 17

Open message sent

Question 18

BGP neighbor state: Open Confirm

Answer 18

Open message received

Question 19

BGP neighbor state: Established

Answer 19

Adjacency established

Question 20

BGP attribute types

Answer 20

Well-known mandatory, well-known discrationary, optional transitive, optional non-transitive

Question 21

Well-known mandatory attributes (O,A,N)

Answer 21

Origin, AS path, Next Hop

Question 22

Well-known discretionary attributes (LP, AA)

Answer 22

Local preference, Atomic Aggregate

Question 23

Optional Transitive attributes (A,C)

Answer 23

Aggregator, Community

Question 24

Optional non-transitive attributes (M,O,CL,CI)

Answer 24

MED, Originator ID, Cluster List, Cluster ID

Question 25

Well-known mandatory description

Answer 25

Must be supported and propagated

Question 26

Well-known discretionary description

Answer 26

Must be supported, propagation optional

Question 27

Optional Transitive description

Answer 27

Marked as partial if not understood by neighbor but will be passed on to it’s next neighbor

Question 28

Optional non-transitive description

Answer 28

Deleted by neighbor if unsupported by neighbor and not passed on to it’s peer/neighbor

Question 29

Attribute description: Origin

Answer 29

IGP, EGP or unkown

Question 30

Attribute description: AS Path

Answer 30

List of AS which the advertisement has traversed

Question 31

Attribute description: Next Hop

Answer 31

External peer in neighboring AS

Question 32

Attribute description: Local Preference

Answer 32

Metric for internal neighbors to reach external destinations. (default 100)

Question 33

Attribute description: Atomic Aggregate

Answer 33

Includes AS’s that were dropped due to route aggregation

Question 34

Attribute description: Multiple Exit Descriminator

Answer 34

MED, Metric for external neighbors to reach local AS (default 0)

Question 35

Attribute description: Weight

Answer 35

The BGP’s Weight Path attribute is the first path attribute BGP checks in the election of the best path in the BGP table on Cisco IOS Routers. BGP prefers the path for the entry with the highest Weight. Weight is a Cisco-specific parameter and it is only locally significant in the Router where it is configured.

Question 36

3 commands needed for eBGP

Answer 36

neighbor x.x.x.x remote-as xxxxx
neighbor x.x.x.x update-source loopback0
neighbor x.x.x.x ebgp-multihop 2