846
Configuring IP Unicast Routing
Configuring BGP
Configuring BGP
The Border Gateway Protocol (BGP) is an exterior gateway protocol used to set up an interdomain routing system for
loop-free exchanges of routing information between autonomous systems. Autonomous systems are made up of routers
that operate under the same administration and that run Interior Gateway Protocols (IGPs), such as RIP or OSPF, within
their boundaries and that interconnect by using an Exterior Gateway Protocol (EGP). BGP Version 4 is the standard EGP
for interdomain routing in the Internet.
For details about BGP configuration and commands, see the BGP documents listed in
Routers that belong to the same autonomous system (AS) and that exchange BGP updates run
internal BGP
(IBGP), and
routers that belong to different autonomous systems and that exchange BGP updates run
external BGP
(EBGP). Most
configuration commands are the same for configuring EBGP and IBGP. The difference is that the routing updates are
exchanged either between autonomous systems (EBGP) or within an AS (IBGP).
shows a
network that is running both EBGP and IBGP.
Figure 101 EBGP, IBGP, and Multiple Autonomous Systems
Before exchanging information with an external AS, BGP ensures that networks within the AS can be reached by defining
internal BGP peering among routers within the AS and by redistributing BGP routing information to IGPs that run within
the AS, such as IGRP and OSPF.
Routers that run a BGP routing process are often referred to as BGP
speakers
. BGP uses the Transmission Control
Protocol (TCP) as its transport protocol (specifically port 179). Two BGP speakers that have a TCP connection to each
other for exchanging routing information are known as
peers
or
neighbors
, Routers A and B
are BGP peers, as are Routers B and C and Routers C and D. The routing information is a series of AS numbers that
describe the full path to the destination network. BGP uses this information to construct a loop-free map of autonomous
systems.
Command
Purpose
clear ip eigrp neighbors
[
if-address
|
interface
]
Delete neighbors from the neighbor table.
show ip eigrp interface
[
interface
] [
as numbe
r]
Display information about interfaces configured for EIGRP.
show ip eigrp neighbors
[
type-number
]
Display EIGRP discovered neighbors.
show ip eigrp topology
[
autonomous-system-number
] | [[
ip-address
]
mask
]]
Display the EIGRP topology table for a given process.
show ip eigrp traffic
[
autonomous-system-number
]
Display the number of packets sent and received for all or a
specified EIGRP process.
AS 100
74775
AS 200
129.213.1.2
175.220.212.1
129.213.1.1
192.208.10.2
AS 300
EBGP
EBGP
192.208.10.1
175.220.1.2
IBGP
Router B
Router A
Router D
Router C
Содержание IE 4000
Страница 12: ...8 Configuration Overview Default Settings After Initial Switch Configuration ...
Страница 52: ...48 Configuring Interfaces Monitoring and Maintaining the Interfaces ...
Страница 108: ...104 Configuring Switch Clusters Additional References ...
Страница 128: ...124 Performing Switch Administration Additional References ...
Страница 130: ...126 Configuring PTP ...
Страница 140: ...136 Configuring CIP Additional References ...
Страница 146: ...142 Configuring SDM Templates Configuration Examples for Configuring SDM Templates ...
Страница 192: ...188 Configuring Switch Based Authentication Additional References ...
Страница 244: ...240 Configuring IEEE 802 1x Port Based Authentication Additional References ...
Страница 274: ...270 Configuring SGT Exchange Protocol over TCP SXP and Layer 3 Transport Configuring Cisco TrustSec Caching ...
Страница 298: ...294 Configuring VLANs Additional References ...
Страница 336: ...332 Configuring STP Additional References ...
Страница 408: ...404 Configuring DHCP Additional References ...
Страница 450: ...446 Configuring IGMP Snooping and MVR Additional References ...
Страница 490: ...486 Configuring SPAN and RSPAN Additional References ...
Страница 502: ...498 Configuring Layer 2 NAT ...
Страница 559: ...555 Configuring Network Security with ACLs How to Configure Network Security with ACLs Creating a Numbered Extended ACL ...
Страница 770: ...766 Configuring IPv6 MLD Snooping Related Documents ...
Страница 930: ...926 Configuring IP Unicast Routing Related Documents ...
Страница 956: ...952 Configuring IPv6 Unicast Routing Configuring IPv6 network 2010 AB8 2 48 network 2010 AB8 3 48 exit address family ...
Страница 976: ...972 Configuring Cisco IOS IP SLAs Operations Additional References ...
Страница 978: ...974 Dying Gasp ...
Страница 990: ...986 Configuring Enhanced Object Tracking Monitoring Enhanced Object Tracking ...
Страница 994: ...990 Configuring MODBUS TCP Displaying MODBUS TCP Information ...
Страница 996: ...992 Ethernet CFM ...
Страница 1030: ...1026 Working with the Cisco IOS File System Configuration Files and Software Images Working with Software Images ...
Страница 1066: ...1062 Using an SD Card SD Card Alarms ...