Hi,
I have some questions regarding BGP
1.Can BGP perform load-balancing? If so how?
2.What is AS-PATH attribute in BGP and does it come into picture while doing load balancing.?
Here is the configuration of PE router and CE where the prefixes highlighted are not received as best in CE and under the path our office AS is shown twice.
My doubt is why the prefixes are learnt as valid but not best best while the remaining were learnt as best and valid.
Kindly help me to understand why the prefixes are not received as *> in CE router.
Thanks.
CE end configuration
====================
B****************Y#sh running-config
Building configuration...
Current configuration : 2249 bytes
!
version 15.1
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
!
hostname B***************Y
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
dot11 syslog
ip source-route
!
!
!
!
!
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
crypto pki token default removal timeout 0
!
!
!
!
!
redundancy
!
!
!
!
!
!
!
!
!
interface Loopback0
ip address 100.96.146.140 255.255.255.255
!
interface Loopback100
ip address 10.143.3.78 255.255.255.255
!
interface Loopback200
ip address 10.143.10.12 255.255.255.255
!
interface FastEthernet0/0
description WAN
ip address 10.60.0.62 255.255.255.252
duplex auto
speed auto
!
interface FastEthernet0/1
description LAN
ip address 10.195.233.2 255.255.255.0
glbp 1 ip 10.195.233.1
glbp 1 priority 130
glbp 1 preempt
duplex auto
speed auto
!
interface BRI0/0/0
no ip address
encapsulation hdlc
shutdown
!
interface Serial0/1/0
no ip address
shutdown
no fair-queue
clock rate 2000000
!
interface Serial0/1/1
no ip address
shutdown
clock rate 2000000
!
router bgp CE AS number
bgp log-neighbor-changes
network 10.60.0.60 mask 255.255.255.252
network 10.143.3.78 mask 255.255.255.255
network 10.143.10.12 mask 255.255.255.255
network 10.195.233.0 mask 255.255.255.0
network 100.96.146.140 mask 255.255.255.255
neighbor 10.60.0.61 remote-as PE ASnumber
!
ip forward-protocol nd
ip http server
no ip http secure-server
!
!
!
!
!
!
!
!
!
control-plane
!
!
!
line con 0
password 7 ******************
line aux 0
line vty 0 4
login local
transport input telnet
transport output telnet
!
scheduler allocate 20000 1000
end
Output for show ip bgp nei <neig IP> routes command in CE router
==================================================
B*********#show ip bgp neighbors 10.60.0.61 routes
BGP table version is 280, local router ID is 100.96.146.140
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, x best-external, f RT-Filter
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 0.0.0.0 10.60.0.61 0 9583 9583 i
*> 10.60.0.0/30 10.60.0.61 0 9583 ?
*> 10.60.0.20/30 10.60.0.61 0 9583 ?
* 10.60.0.60/30 10.60.0.61 0 0 9583 ?
*> 10.128.0.0/23 10.60.0.61 0 9583 9583 i
*> 10.128.24.0/24 10.60.0.61 0 9583 9583 i
*> 10.128.28.0/23 10.60.0.61 0 9583 9583 i
*> 10.128.72.0/27 10.60.0.61 0 9583 9583 i
* 10.143.3.78/32 10.60.0.61 0 0 9583 ?
* 10.143.10.12/32 10.60.0.61 0 0 9583 ?
* 10.195.233.0/24 10.60.0.61 0 0 9583 ?
*> 100.64.13.48/28 10.60.0.61 0 9583 ?
*> 100.64.33.192/30 10.60.0.61 0 9583 ?
*> 100.65.191.52/30 10.60.0.61 0 9583 ?
*> 100.65.215.0/26 10.60.0.61 0 9583 ?
*> 100.65.235.190/32
10.60.0.61 0 9583 ?
*> 100.65.235.191/32
10.60.0.61 0 9583 ?
*> 100.67.15.208/29 10.60.0.61 0 9583 ?
*> 100.67.15.242/32 10.60.0.61 0 9583 ?
*> 100.67.36.72/29 10.60.0.61 0 9583 ?
*> 100.67.51.208/29 10.60.0.61 0 9583 ?
*> 100.67.57.16/30 10.60.0.61 0 9583 ?
*> 100.96.3.252/30 10.60.0.61 0 9583 ?
*> 100.96.110.176/30
10.60.0.61 0 9583 ?
*> 100.96.129.192/30
10.60.0.61 0 9583 ?
* 100.96.146.140/32
10.60.0.61 0 0 9583 ?
*> 100.96.201.182/31
10.60.0.61 0 9583 ?
*> 100.96.215.142/32
10.60.0.61 0 9583 ?
*> 100.96.215.150/32
10.60.0.61 0 9583 ?
Network Next Hop Metric LocPrf Weight Path
*> 100.96.236.161/32
10.60.0.61 0 9583 ?
*> 100.96.236.162/32
10.60.0.61 0 9583 ?
*> 119.227.22.64/29 10.60.0.61 0 9583 ?
*> 119.227.126.0/25 10.60.0.61 0 9583 ?
*> 119.227.222.8/29 10.60.0.61 0 9583 ?
*> 119.227.222.16/28
10.60.0.61 0 9583 ?
*> 124.7.159.5/32 10.60.0.61 0 9583 ?
*> 124.7.159.9/32 10.60.0.61 0 9583 ?
*> 124.7.159.13/32 10.60.0.61 0 9583 ?
*> 172.20.31.74/32 10.60.0.61 0 9583 ?
PE end configuration (ASR router)
==================
#sh run router bgp 9583 vrf 1*****************E nei 10.60.0.62
Wed Aug 14 08:09:31.163 IST
router bgp 9583
vrf 1**********************E
neighbor 10.60.0.62
remote-as CE AS number
description B********************7
address-family ipv4 unicast
route-policy B*******************7 in
maximum-prefix 1000 75
route-policy DEFAULT_PASS out
as-override
!
!
!
show rpl route-policy B**************7
Wed Aug 14 08:09:45.172 IST
route-policy B***************7
if destination in B****************7 then
pass
endif
end-policy
!
show rpl prefix-set B**************7
Wed Aug 14 08:09:57.124 IST
prefix-set B**************7
10.195.233.0/24,
100.96.146.140/32,
10.143.3.78/32,
10.143.10.12/32
end-set
!
Output for show bgp vrf <vrfname> nei <neigh ip> routes in PE router
========================================================
Status codes: s suppressed, d damped, h history, * valid, > best
i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
Route Distinguisher: 9583:12029 (default for vrf 1********************E)
* 10.143.3.78/32 10.60.0.62 0 0 CE AS num i
* 10.143.10.12/32 10.60.0.62 0 0 CE AS num i
* 10.195.233.0/24 10.60.0.62 0 0 CE AS num i
* 100.96.146.140/32 10.60.0.62 0 0 CE AS num i
Processed 4 prefixes, 4 paths
