BGP

8

Border Gateway Protocol (BGP) BGP, BGP . , , BGP: .

    BGP

, RIP, OSPF EIGRP, , , BGP (PAs).

BGP:

  1. BGP

: BGP 7


BGP- (Path Attributes)

BGP BGP , , , , , BGP .

BGP- , .

  • Well-Known Mandatory
  • Well-Known Discretionary
  • Optional Transitive
  • Optional Non-Transitive

, Well-Known. Well-Known , . Optional. Optional , BGP .

mandatory discretionary, Well-Known. Mandatory , . , , . Discretionary, , , .

- . , . , .

1 , TPA1 ATL. , show ip bgp , BGP. , Next Hop, Metric (MED), LocPrf (Local Preference), Weight, Path (AS Path).

TPA1#show ip bgp
BGP table version  is 4, local router ID is 10.10.10.1
Status codes: s suppressed, d damped, h history, * valid, > best, i  internal, r RIB-failure, S Stale
Origin codes^ I  IGP, e  EGP, ? - incomplete 
	Network	Next Hop	Metric	LocPrf	Weight	Path
*>	100.100.100.0/24	10.10.10.2	0			200          i

Origin

ORIGIN BGP- , . , : IGP, EGP Incomplete. 1, , Cisco , i, e, ?. , 1, , IGP. , . . IGP , (Gateway Protocol). , OSPF, BGP, BGP. , IGP - , . , , BGP.

EGP (Exterior Gateway Protocol), BGP. .

Incomplete , BGP , . , Border Gateway Protocol - , IGP.

, . , , BGP . . , , , .


AS Path

AS Path - well-known mandatory . , Border Gateway Protocol.

, 1, , TPA. TPA1, TPA AS 100 AS Path, , , AS iBGP.

TPA1 ATL, 100 . , ATL ATL2 AS. , ATL2 - AS, AS 200. , , AS path, 2, AS, (100), - AS, (342).

2: BGP AS Path

 BGP AS Path

Next Hop

, BGP Next Hop. , , . Next Hop . , , , Next Hop BGP , IGP. , , iBGP eBGP.

, , Next Hop IP- , . . Next Hop hop-by-hop.

BGP, eBGP , Next Hop ( ) IP- eBGP, . IP- eBGP Next Hop, iBGP iBGP. Next Hop, IP-, , . , AS, . , BGP AS-to-AS hop-to-hop.

. , , BGP Next Hop , . , BGP , Next Hop.

, . iBGP , Next Hop , . neighbor, 3.

ATL (config)# router bgp 200
ATL (config-router)# neighbor 10.10.10.1 next-hop-self

BGP Weight ()

Weight () - BGP, Cisco. , , Cisco , Weight .

Weight , . Weight - , . Weight - 0 65535, , . , 32768. 0.

? , BGP. . , , . - , BGP.


BGP Best Path ( )

, , IGP , . OSPF , . BGP , . BGP. 2 ( ), Cisco BGP.

, , . , - , , BGP. , , .


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