This area lists added capacity and facts to annular out the advantage of the capacity in this chapter.
Unlike best of the Cisco Press Assay Certification Guides, this “Foundation Summary” does not
repeat advice presented in the “Foundation Topics” area of the chapter. Please booty the
time to apprehend and abstraction the capacity in the “Foundation Topics” area of the chapter, as able-bodied as
review items acclaimed with a Key Topic icon.
Table 11-12 lists some of the key RFCs for BGP.
Table 11-13 lists the BGP aisle attributes mentioned in this chapter, and describes their purpose.
Table 11-12 Protocols and Standards for Affiliate 12
Topic Standard
BGP-4 RFC 1771
BGP Confederations RFC 3065
BGP Avenue Absorption RFC 2796
MD5 Authentication RFC 2385
Table 11-13 BGP PAs
Path Aspect Description Characteristics
AS_PATH Lists ASNs through which the avenue has been
advertised
Well known
Mandatory
NEXT_HOP Lists the next-hop IP abode acclimated to ability an
NLRI
Well known
Mandatory
AGGREGATOR Lists the RID and ASN of the router that
created a arbitrary NLRI
Optional Transitive
ATOMIC_AGGREGATE Tags a arbitrary NLRI as actuality a arbitrary Able-bodied known
Discretionary
ORIGIN Value implying from area the avenue was
taken for bang into BGP; i(IGP), e (EGP),
or ? (incomplete information)
Well known
Mandatory
Foundation Arbitrary 395
Table 11-15 lists some of the best accepted Cisco IOS commands accompanying to the capacity in this
chapter.
Path Aspect Description Characteristics
ORIGINATOR_ID Acclimated by RRs to denote the RID of the iBGP
neighbor that injected the NLRI into the AS
Optional
Nontransitive
CLUSTER_LIST Acclimated by RRs to account the RR array IDs in
order to anticipate loops
Optional
Nontransitive
Table 11-14 lists and describes the methodes to acquaint entries into the BGP table.
Table 11-14 Summary: Methods to Acquaint Entries into the BGP Table
Method Arbitrary Description
network command Advertises a avenue into BGP. Depends on the actuality of the configured
network/subnet in the IP acquisition table.
Redistribution Takes IGP, static, or affiliated routes; metric (MED) appointment is not
required.
Manual summarization Requires at atomic one basal subnet in the BGP table; options for
keeping all basal subnets, suppressing all from advertisement, or
suppressing a subset from actuality advertised.
default-information
originate
Requires a absence avenue in the IP acquisition table, additional the redistribute
command.
neighbor defaultoriginate
With the alternative avenue map, requires the avenue map to bout the IP routing
table with a admittance activity afore announcement a absence route. Without the
route map, the absence is consistently advertised.
Table 11-15 Command Advertence for Affiliate 11
Command Command Mode and Description
aggregate-address abode affectation [as-set]
[summary-only] [suppress-map map-name]
[advertise-map map-name]
[attribute-map map-name]
BGP mode; summarizes BGP routes, suppressing all/
none/some of the basal subnets
auto-summary BGP mode; enables automated summarization to
classful boundaries of locally injected routes
continues
Table 11-13 BGP PAs (Continued)
396 Affiliate 11: BGP
Command Command Mode and Description
bgp client-to-client absorption BGP mode; on by default, tells a RR server to reflect
routes abstruse from a applicant to added clients
bgp cluster-id cluster-id BGP mode; defines a nondefault RR array ID to a
RR server
bgp amalgamation identifier as-number BGP mode; for confederations, defines the ASN used
for the absolute AS as apparent by added autonmous systems
bgp amalgamation aeon as-number
[... as-number]
BGP mode; for confederations, identifies which
neighboring ASNs are in added amalgamation subautonmous
systems
bgp log-neighbor-changes BGP mode; on by default, it tells BGP to actualize log
messages for cogent changes in BGP operation
bgp router-id ip-address BGP mode; defines the BGP router ID.
default-information arise BGP mode; appropriate to acquiesce a changeless absence avenue to
be redistributed into BGP
default-metric cardinal BGP mode; sets the absence metric assigned to routes
redistributed into BGP; commonly defaults to the IGP
metric for anniversary route
distance bgp external-distance internaldistance
local-distance
BGP mode; defines the authoritative ambit for
eBGP, iBGP, and locally injected BGP routes
neighbor {ip-address | peer-group-name}
default-originate [route-map map-name]
BGP mode; tells the router to add a absence avenue to
the BGP Update beatific to this neighbor, beneath the
conditions set in the alternative avenue map
neighbor {ip-address | peer-group-name}
description text
BGP mode; adds a anecdotic argument advertence in the
BGP configuration
neighbor {ip-address | peer-group-name}
ebgp-multihop [ttl]
BGP mode; for eBGP peers, sets the TTL in packets
sent to this associate to article beyond than the default
of 1
neighbor ip-address | peer-group-name
next-hop-self
BGP mode; causes IOS to displace the NEXT_HOP PA
to the IP abode acclimated as the antecedent abode of
Updates beatific to this neighbor
neighbor {ip-address | peer-group-name}
password string
BGP mode; defines the key acclimated in an MD5 assortment of
all BGP letters to this neighbor
neighbor ip-address peer-group peer-groupname
BGP mode; assembly a neighbor’s IP abode as part
of a associate group
Table 11-15 Command Advertence for Affiliate 11 (Continued)
Foundation Arbitrary 397
Command Command Mode and Description
neighbor peer-group-name peer-group BGP mode; defines the name of a associate group
neighbor {ip-address | peer-group-name}
remote-as as-number
BGP mode; defines the AS of the neighbor
neighbor {ip-address | peer-group-name}
shutdown
BGP mode; administratively shuts bottomward a neighbor,
stopping the TCP connection
neighbor [ip-address | peer-group-name]
timers keepalive holdtime
BGP mode; sets the two BGP timers, aloof for this
neighbor
neighbor {ip-address | ipv6-address | peergroup-
name} update-source interface-type
interface-number
BGP mode; defines the antecedent IP abode acclimated for
BGP letters beatific to this neighbor
network {network-number [mask networkmask]
[route-map map-tag]
BGP mode; causes IOS to add the authentic prefix to
the BGP table if it exists in the IP acquisition table
router bgp as-number Global command; defines the ASN and puts the user
in BGP mode
synchronization BGP mode; enables BGP synchronization
timers bgp keepalive holdtime BGP mode; defines BGP timers for all neighbors
show ip bgp [network] [network-mask]
[longer-prefixes] [prefix-list prefix-list-name |
route-map route-map-name] [shorter prefixes
mask-length]
Exec mode; lists capacity of a router’s BGP table
show ip bgp injected-paths Exec mode; lists routes locally injected into BGP
show ip bgp neighbors [neighbor-address]
[received-routes | routes | advertised-routes |
{paths regexp} | dampened-routes | received
prefix-filter]]
Exec mode; lists advice about routes beatific and
received to accurate neighbors
show ip bgp peer-group [peer-group-name]
[summary]
Exec mode; lists capacity about a accurate associate group
show ip bgp arbitrary Exec mode; lists basal statistics for anniversary BGP peer
Table 11-15 Command Advertence for Affiliate 11 (Continued)
398 Affiliate 11: BGP
Memory Builders
The CCIE Acquisition and Switching accounting exam, like all Cisco CCIE accounting exams, covers a fairly
broad set of topics. This area provides some basal accoutrement to advice you exercise your anamnesis about
some of the broader capacity covered in this chapter.
Fill in Key Tables from Memory
Appendix E, “Key Tables for CCIE Study,” on the CD in the aback of this book contains abandoned sets
of some of the key arbitrary tables in anniversary chapter. Print Appendix E, accredit to this chapter’s tables
in it, and ample in the tables from memory. Accredit to Appendix F, “Solutions for Key Tables for CCIE
Study,” on the CD to analysis your answers.
Definitions
Next, booty a few moments to address bottomward the definitions for the afterward terms:
path attribute, BGP table, BGP Update, established, iBGP, eBGP, EGP, BGP, peer
group, eBGP multihop, free system, AS number, AS_PATH, ORIGIN,
NLRI, NEXT_HOP, MULTI_EXIT_DISC, LOCAL_PREF, acquisition atramentous hole,
synchronization, confederation, avenue reflector, amalgamation identifier, sub-AS,
route reflector server, avenue reflector client, avenue reflector nonclient, confederation
AS, amalgamation eBGP, weight
Refer to the comment to analysis your answers.