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Question 496

SIMULATION

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Guidelines

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This is a lab item in which tasks will be performed on virtual devices.

• Refer to the Tasks tab to view the tasks for this lab item.

• Refer to the Topology tab to access the device console(s) and perform the tasks.

• Console access is available for all required devices by clicking the device icon or using the tab(s) above the console window.

• All necessary preconfigurations have been applied.

• Do not change the enable password or hostname for any device.

• Save your configurations to NVRAM before moving to the next item.

• Click Next at the bottom of the screen to submit this lab and move to the next question.

• When Next is clicked, the lab closes and cannot be reopened.

Topology

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Tasks

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A company is connected to an ISP and some of the networks between the ISP and the company are not reachable. Troubleshoot and resolve the issues to achieve these goals:

1. A single /16 is advertised for all infrastructure-connected interfaces that belong to the 10.20.x.x network using BGP network commands from border routers connected to the ISP. Configuration modification is allowed in R4 and R5 to achieve the results. Do not use the BGP aggregate command.

2. R6 receives the ISP R2 Loopback2 from R4 and receives a summary address for both Loopbacks of ISP R2 from R4 or R5. Use BGP attribute local-preference, add , for example, for R6, use “default+6 = value to be used”. Use the existing prefix lists or route maps with the sequence numbering starting at 10 and added in increments of 10.

3. R6 receives the ISP R2 Loopback1 from R5 and receives a summary address for both Loopbacks of ISP R2 from R4 or R5 using the same guidelines.

4. R6 advertises its Loopback1 /24 address through BGP.

    Correct Answer:

Discussion
[Removed]

Labbed as best I could without seeing the actual configs. Part 1 Router 4+5 Add static route to 10.20.0.0 255.255.0.0 null0 Advertise to BGP with network statement Part 2 Router 4 and 5. Match relevant R2 loopback using a standard access list. Create route map (question implies modification of existing). Permit 10 match access list and set LP to 100+routerID. Permit 20 match all/permit all (blank). Part3 Advertise Loopback on R6 using network statement.

halil395

R4# ! ip route 10.20.0.0 255.255.0.0 Null0 ! router bgp 65000 network 10.20.0.0 mask 255.255.0.0 aggregate-address 192.168.2.0 255.255.254.0 neighbor 10.20.6.6 route-map BGP-R6 out ! ip prefix-list 65000-in seq 5 permit 192.168.2.0/24 ! route-map BGP-R6 permit 10 match ip address prefix-list 65000-in set local-preference 104 ! route-map BGP-R6 permit 20 #################### R5# ! ip route 10.20.0.0 255.255.0.0 Null0 ! router bgp 65000 network 10.20.0.0 mask 255.255.0.0 aggregate-address 192.168.2.0 255.255.254.0 neighbor 10.20.6.6 route-map BGP-R6 out ! ip prefix-list 65001-in seq 5 permit 192.168.3.0/24 ! route-map BGP-R6 permit 10 match ip address prefix-list 65001-in set local-preference 105 ! route-map BGP-R6 permit 20 ! #################### R6# ! router bgp 65000 network 172.16.6.0 mask 255.255.255.0 !

Pietjeplukgeluk

You really nailed the essence in my opinion.

ExamNinja1

I am a little lost on what might be going on under the hood on this one. Can someone explain why we would be installing a null0 route here.

Gramterre

Because we need the route to advertise it into bgp, as we are not allowed to use the aggregate command.

Ghauri777

R4 router bgp 65000 bgp log-neighbor-changes network 10.20.0.0 mask 255.255.0.0 aggregate-address 192.168.0.0 255.255.252.0 as-set neighbor 10.10.1.1 remote-as 65001 neighbor 10.10.1.1 ebgp-multihop 2 neighbor 10.10.1.1 update-source Loopback0 neighbor 10.10.1.1 route-map R2-L2 in ip prefix-list 1 seq 5 permit 192.168.3.0/24 match ip address prefix-list 1 route-map R2-L2 permit 10 match ip address prefix-list 1 set local-preference 104 route-map R2-L2 permit 20 ----------------------------------- R5 router bgp 65000 bgp log-neighbor-changes network 10.20.0.0 mask 255.255.0.0 aggregate-address 192.168.0.0 255.255.252.0 as-set neighbor 10.10.3.3 remote-as 65001 neighbor 10.10.3.3 ebgp-multihop 2 neighbor 10.10.3.3 update-source Loopback0 neighbor 10.10.3.3 route-map R2-L1 in ip prefix-list 1 seq 5 permit 192.168.2.0/24 match ip address prefix-list 1 set local-preference 106 route-map R2-L1 permit 10 match ip address prefix-list 1 set local-preference 106 route-map R2-L1 permit 20 --------------- R6 router bgp 65000 bgp log-neighbor-changes network 172.16.6.0 mask 255.255.255.0

aqwsdfghjklp

I don't know why you need the "as-set" command.

aqwsdfghjklp

Is this a config?

[Removed]

Its says you cannot use the aggregate command. As the published solution states - add a null static route and then advertise into BGP