From: Mike Haddad (mike.haddad@hotmail.com)
Date: Wed Apr 02 2008 - 00:16:52 ART
You're right the questions specifies "Devices that are running BGP". I would
direct this question to the IE Expert support team who will probably have to
correct the question wording.
> Date: Wed, 2 Apr 2008 08:13:24 +0800> From: ccie2323@gmail.com> To:
ccielab@groupstudy.com> Subject: IE Core LAB 3 Task 5.1 solution discussion> >
5.1. BGP Peerings> Configure BGP AS 200 on R3.> Configure BGP AS 100 on
R1, R2, and R6.> Configure BGP peerings between R1 & R2, R1 & R3, R1 & R6,
R2 & R6,> R3 & BB2, and R6 & BB1.> The peering between R3 and BB2 should be
authenticated with the> password CISCO.> Do not enable BGP on R5 or SW3.>
All devices running BGP should have reachability to all BGP learned>
prefixes.> Do not use tunelling to accomplish this.> > > Solution Guide>
R1:> router bgp 100> neighbor 190.1.0.2 remote-as 100> neighbor 190.1.0.6
remote-as 100> neighbor 190.1.135.3 remote-as 200> R2:> router bgp 100>
neighbor 190.1.135.1 remote-as 100> neighbor 190.1.0.6 remote-as 100> R3:>
router bgp 200> neighbor 190.1.135.1 remote-as 100> neighbor 192.10.1.254
remote-as 254> neighbor 192.10.1.254 password CISCO> !> router ospf 1>
redistribute bgp 200 subnets route-map BGP->OSPF> !> route-map BGP->OSPF
permit 10> match as-path 1> !> ip as-path access-list 1 permit ^254_> R6:>
router bgp 100> network 190.1.0.0 mask 255.255.255.0> aggregate-address
190.1.0.0 255.255.0.0 summary-only> neighbor 190.1.135.1 remote-as 100>
neighbor 190.1.0.2 remote-as 100> neighbor 54.1.1.254 remote-as 54> !> router
eigrp 10> redistribute bgp 100 metric 1 1 1 1 1 route-map BGP->EIGRP>
distribute-list prefix BGP out Serial0/0/0.1> !> route-map BGP->EIGRP permit
10> match as-path 1> !> ip as-path access-list 1 permit ^54_> !> ip
prefix-list BGP seq 5 deny 28.119.16.0/24> ip prefix-list BGP seq 10 deny
28.119.17.0/24> ip prefix-list BGP seq 15 deny 112.0.0.0/8> ip prefix-list BGP
seq 20 deny 113.0.0.0/8> ip prefix-list BGP seq 25 deny 114.0.0.0/8> ip
prefix-list BGP seq 30 deny 115.0.0.0/8> ip prefix-list BGP seq 35 deny
116.0.0.0/8> ip prefix-list BGP seq 40 deny 117.0.0.0/8> ip prefix-list BGP
seq 45 deny 118.0.0.0/8> ip prefix-list BGP seq 50 deny 119.0.0.0/8> ip
prefix-list BGP seq 55 permit 0.0.0.0/0 le 32> > Task 5.1 Breakdown> When
redistributing from BGP into IGP care needs to be taken to ensure that> only
the BGP routes learned at the edge are redistributed. If all routes> were>
redistributed from BGP into IGP, traffic could be blackholed. This can ocurr>
by> follwing the lower administrative distance IGP over iBGP routes toward
the> wrong> edge of the network.> On R6, if the routes redistributed from BGP
into EIGRP are not filtered from> being advertised back to BB1, a routing loop
will result. This will happen> because> BB1 would prefer the EIGRP routes
rather than the BGP routes to BB2 where> the> routes are originated.> Finally,
the task states that all device running BGP need reachability to> the>
advertised routes which necessitates advertising the internal network space>
to> AS 54. This is done using an aggregate route on R6.> > My Question is why
does the solution guide solve the task by redistributing> BGP into IGP? From
what i understand its just a blackhole problem on R5. Am> i missing anything?>
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