4.6 Configure and verify single-homed branch connectivity using eBGP IPv4 (limited to peering and route advertisement using Network command only)

Screenshot_2018-11-26_07-27-58

Configuring

Using the above topology we will configure a single homed eBGP. Download lab here.

On ISP1:

router bgp 101
 no synchronization
 bgp log-neighbor-changes
 neighbor 192.1.100.2 remote-as 3
 no auto-summary
!

On ENT1:

router bgp 3
 no synchronization
 bgp log-neighbor-changes
 network 192.0.101.0
 network 192.0.102.0
 neighbor 192.1.100.1 remote-as 101
 no auto-summary
!

All that is left is to use OSPFv2 to distribute routes from FIREWALL to ENT1.

Verifying

To verify just use the following “show” commands.

ISP1#show ip bgp neighbors 
BGP neighbor is 192.1.100.2,  remote AS 3, external link
  BGP version 4, remote router ID 192.1.100.2
  BGP state = Established, up for 00:00:42
  Last read 00:00:42, last write 00:00:42, hold time is 180, keepalive interval is 60 seconds
... <rest of output deleted>
ISP1#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area 
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

B    192.0.102.0/24 [20/2] via 192.1.100.2, 00:00:50
C    192.1.100.0/24 is directly connected, GigabitEthernet0/0
B    192.0.101.0/24 [20/2] via 192.1.100.2, 00:00:50
ISP1#show ip protocols 
Routing Protocol is "bgp 101"
  Outgoing update filter list for all interfaces is not set
  Incoming update filter list for all interfaces is not set
  IGP synchronization is disabled
  Automatic route summarization is disabled
  Neighbor(s):
    Address          FiltIn FiltOut DistIn DistOut Weight RouteMap
    192.1.100.2                                          
  Maximum path: 1
  Routing Information Sources:
    Gateway         Distance      Last Update
    192.1.100.2           20      00:01:24
  Distance: external 20 internal 200 local 200

ISP1#

Perform the same “show” commands on ENT1 to verify association.

Using a ping and traceroute command can check the Layer 3 connectivity for the entire path:

SERV1> ping 192.1.100.1
84 bytes from 192.1.100.1 icmp_seq=1 ttl=253 time=40.158 ms
84 bytes from 192.1.100.1 icmp_seq=2 ttl=253 time=21.494 ms
84 bytes from 192.1.100.1 icmp_seq=3 ttl=253 time=27.591 ms
84 bytes from 192.1.100.1 icmp_seq=4 ttl=253 time=22.309 ms
84 bytes from 192.1.100.1 icmp_seq=5 ttl=253 time=23.390 ms

SERV1> trace 192.1.100.1
trace to 192.1.100.1, 8 hops max, press Ctrl+C to stop
 1   192.0.101.1   2.539 ms  9.359 ms  9.216 ms
 2   10.0.0.1   19.470 ms  20.039 ms  19.656 ms
 3   *192.1.100.1   39.910 ms (ICMP type:3, code:3, Destination port unreachable)  *

SERV1>

Note the exam topics to not mention troubleshooting. Just configuring and verifying….

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s