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CCNP ENARSI lab 16 of 35

BGP neighbours: iBGP, eBGP multihop, next-hop-self, 4-byte and private AS

Bring up every kind of BGP session an enterprise edge needs: an iBGP mesh over loopbacks with a peer group, an authenticated eBGP multihop session to a 4-byte-AS provider, and an eBGP session to a subsidiary whose private AS must never reach the Internet.

Run this lab

It needs Lite: its 5 nodes are set to 5 vCPU and 2,560 MB in total. That fits the free demo too.

In your workspace: Shared, then CCNP ENARSI 300-410 guided labs, then 16 - BGP neighbours - iBGP eBGP multihop next-hop-self 4-byte and private AS

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Level
Intermediate
Time
About 80 minutes
Nodes need
5 vCPU, 2,560 MB
Smallest plan
Lite

The scenario

Kingfisher Logistics (AS 64500) has three routers: R1 connects to its Internet provider, ISP-A, R2 connects to a recently acquired subsidiary, and R3 hosts the public services block 203.0.113.128/25. OSPF already gives every router reachability to every loopback. You'll build BGP from scratch:

  • an iBGP full mesh between the three routers' Loopback0 addresses, configured with a peer group;
  • eBGP to ISP-A, which uses the 4-byte AS 65550 and insists on peering between loopbacks with MD5 authentication (R1 uses Loopback100, 203.0.113.250; ISP-A uses 198.51.100.4);
  • eBGP to the subsidiary, which still uses the private AS 65010 and has asked for 10 s keepalive / 30 s hold timers. Its private AS must never appear in the Internet's view of the subsidiary's prefix.
DeviceInterfaceAddressNotes
R1Lo0 / Lo10010.255.0.1/32 / 203.0.113.250/32iBGP source / ISP peering source
R1Gi0/2203.0.113.1/30to ISP-A R4 (203.0.113.2)
R2Lo010.255.0.2/32iBGP source
R2Gi0/2192.168.25.1/30to subsidiary R5 (192.168.25.2)
R3Lo0 / Lo110.255.0.3/32 / 203.0.113.129/25iBGP source / public services
R4 (ISP-A, AS 65550)Lo0 / Lo1198.51.100.4/32 / 192.0.2.1/24peering address / Internet content
R5 (subsidiary, AS 65010)Lo1172.30.1.1/24subsidiary LAN

ISP-A sends a default route and 192.0.2.0/24. R4 and R5 are pre-configured and are waiting for you.

What you’ll practise

  • Build iBGP sessions between loopbacks with update-source and a peer group
  • Explain why iBGP needs next-hop-self (or an IGP route to the next hop)
  • Peer eBGP between loopbacks with ebgp-multihop and MD5 authentication
  • Work with 4-byte AS numbers in asplain and asdot notation
  • Remove a private AS from the AS path towards a provider; tune neighbour timers
  • Read BGP neighbour states and the summary table

The tasks

  1. iBGP between loopbacks with a peer group
  2. eBGP multihop to the 4-byte AS provider, with MD5
  3. Fix the iBGP next hop
  4. eBGP to the subsidiary, with its timers
  5. Keep the private AS out of the Internet
  6. Test

The Lab Tasks pane has the scenario, these tasks, the checks to run, hints and the full solution.

Topology and devices

The network as it opens in EVE-NG, drawn from the lab’s own canvas, and the image each node runs.

Topology of BGP neighbours - iBGP eBGP multihop next-hop-self 4-byte and private AS5 nodes, 5 links. Every link is listed as text below the diagram.R1R2R3R4R5Gi0/1Gi0/1Gi0/0Gi0/0Gi0/0Gi0/1Gi0/2Gi0/0Gi0/2Gi0/0
5 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • R1 Gi0/0 to R3 Gi0/0
  • R2 Gi0/0 to R3 Gi0/1
  • R1 Gi0/1 to R2 Gi0/1
  • R1 Gi0/2 to R4 Gi0/0
  • R2 Gi0/2 to R5 Gi0/0
Nodes in BGP neighbours: iBGP, eBGP multihop, next-hop-self, 4-byte and private AS, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
R1Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
R2Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
R3Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
R4Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
R5Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB

How to open this lab

  1. Sign in to your workspace at lab.cloudlabbox.com.

  2. In File Manager, open Shared, then the folder CCNP ENARSI 300-410 guided labs.

  3. Open 16 - BGP neighbours - iBGP eBGP multihop next-hop-self 4-byte and private AS and start its nodes, then open Lab Tasks for the scenario and the steps.

The lab is read-only. You can start the nodes and configure the devices, but changes to the topology can’t be saved. To change it, rebuild it in your own folder.

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CloudLabBox is independent of Cisco. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.