Cisco Press - Ccnp Route - Bgp Key Terms

Front 1

Public IP Address

Back 1

An IP address is considered public if the IP number is valid and falls outside any of the IP address ranges reserved for private uses by Internet standards

Front 2

Private IP Address

Back 2

Front 3

NAT

Back 3

Network Address Translation

NAT allows an enterprise to use private IP addresses for each host, plus a small number of public addresses.

Front 4

PAT

Back 4

Port Address Translation

Port address translation (PAT) is a function that allows multiple users within a private network to make use of a minimal number of IP addresses. Its basic function is to share a single IP public address between multiple clients who need to use the Internet publicly. It is an extension of network address translation (NAT).

Front 5

AS Sequence

Back 5

AS Seq

This is the order in which the AS chooses its path.

Front 6

PA

Back 6

Path Attribute

Define information about a path or route through a network.

Front 7

AS Path

Back 7

Autonomous System Path

This has many subcomponents such as AS Seq

Front 8

Public ASN

Back 8

Public Autonomous System Number

Assigned by IANA similar to IP addresses. Public ASN are 1 - 64495

Front 9

Default Route

Back 9

A specific route set on the router to reach a destination.

Front 10

Single Homed

Back 10

Single ISP with a Single Link

Front 11

Dual Homed

Back 11

Two (or more) links to the internet, but with all links connecting to a single ISP

Front 12

Single multihomed

Back 12

Single link per ISP

Front 13

Dual multihomed

Back 13

Two or more links each to two or more different ISPs

Front 14

ASN

Back 14

Autonomous System Number

An ASN is a globally unique number used to identify an Autonomous System.

NOTE:

Those numbers are 1 through 65535

Front 15

eBGP Multihop

Back 15

This is the 5th configuration step for using loopback IP addresses with eBGP peers

NOTE:

The default time to live (TTL) is one and a mulltihop requires more there for the packet is dropped unless discarded.

Front 16

Update Source (BGP)

Back 16

The BGP update source on one router must match the IP address configured on the other router's neighbor command, and vice versa.

Front 17

BGP Table

Back 17

List of paths

Front 18

Requirements for forming eBGP neighbors.

Back 18

• A local router's ASN must match the neighboring router's reference on that ASN
• Router IDs cannot Match
• If Configured, MD5 authentication must pass
• Each router must be a part of a TCP connection with the other router

Front 19

BGP Open Message

Back 19

This generally performs the same functions as the EIGRP or OSPF hello messages.

Front 20

Idle

Back 20

The BGP process is either administratively down or awaiting the next retry attemp

Front 21

Connect

Back 21

The BGP process is waiting for the TCP connection to be completed

Front 22

Active

Back 22

The TCP connection has been completed, but no BGP messages have been sent to the peer yet

Front 23

Opensent

Back 23

The TCP connection exists, and a BGP open message has been sent to the peer, but the matching Open message has not yet been received from the other router

Front 24

Openconfirm

Back 24

An open message has been both sent to and received from the other router. It is waiting for a BGP keepalive message to determine if a neighbor is matched

Front 25

Established

Back 25

All neighbor parameters match, the neighbor relationship works, and the peers can now exchange update messages

Front 26

Open

Back 26

Used to establish a neighbor relationship and exchange basic parameters, including ASN and MD5 authentication values

Front 27

Keepalive

Back 27

Sent on a periodic basis to maintain neighbor relationship.

NOTE:

If it does not receive a resopnce within the hold timer the neighbor is brought to a down state

Front 28

Update

Back 28

Used to exchange PAs and the associated prefix/length (NLRI) that use those attributes

Front 29

NLRI

Back 29

Network Layer Reachability Information

is the same thing as

prefix and length

Front 30

Notification

Back 30

Used to signal a BGP error: Typically results in a reset to the neighbor relationship

Front 31

null0

Back 31

This is a discard route

NOTE:

This is not meant to be advertised, it's only purpose is to enable the operation of the network command

Front 32

What Command

List possible default routes

Back 32

show ip bgp

Front 33

What Command

List possible routes per prefix

Back 33

show ip bgp prefix[subnet-mask]

Front 34

What Command

List routes learned from one neighbor, before any inbound filtering is applied

Back 34

show ip bgp neighbors ip-address received routes

Front 35

What Command

List routes learned from a specific neighbor that passed any inbound filters

Back 35

show ip bgp neighbors ip-address routes

Front 36

What Command

List routes advertised to a neighbor after applying outbound filtering

Back 36

show ip bgp neighbors ip-address advertised-routes

Front 37

What Command

List the number of prefixes per learned neighbor

Back 37

show ip bgp summary