Before diving into OSPF adjacency states and Link-State Advertisements (LSAs), we require a physical baseline. Part 1 establishes our 6-node Nokia SR OS environment in Containerlab, laying down the physical interfaces, point-to-point /30 subnets, and system loopbacks needed before bringing up dynamic routing.
CLI Note: All configuration snippets and output examples in this series are written using Nokia SR OS MD-CLI (Model-Driven CLI). If you are adapting these examples for Classic CLI, context paths and edit modes will differ.
Topology Diagram
Containerlab Topology File (topology.clab.yml)
name: OSPF-Lab
topology:
defaults:
kind: nokia_srsim
image: localhost/nokia/srsim:25.7.R1
type: sr-1
license: license/license.txt
nodes:
r1:
mgmt-ipv4: 172.20.20.9
r2:
mgmt-ipv4: 172.20.20.2
r3:
mgmt-ipv4: 172.20.20.3
r4:
mgmt-ipv4: 172.20.20.4
r5:
mgmt-ipv4: 172.20.20.5
r6:
mgmt-ipv4: 172.20.20.6
links:
# --- CE to PE Links ---
- endpoints: ["r1:1/1/c1/1", "r2:1/1/c1/1"]
- endpoints: ["r5:1/1/c1/1", "r6:1/1/c1/1"]
# --- Core Links ---
- endpoints: ["r2:1/1/c2/1", "r3:1/1/c1/1"]
- endpoints: ["r2:1/1/c3/1", "r4:1/1/c1/1"]
- endpoints: ["r3:1/1/c2/1", "r5:1/1/c2/1"]
- endpoints: ["r4:1/1/c3/1", "r5:1/1/c3/1"]
Addressing Plan
System (Loopback) Interfaces
| Node | System IP Address | Prefix Length |
|---|---|---|
| R1 | 10.100.1.1 | /32 |
| R2 | 10.100.1.2 | /32 |
| R3 | 10.100.1.3 | /32 |
| R4 | 10.100.1.4 | /32 |
| R5 | 10.100.1.5 | /32 |
| R6 | 10.100.1.6 | /32 |
Physical Interfaces
Router R1
| Interface Name | Port ID | IPv4 Address | Prefix Length | Subnet | Neighbor |
|---|---|---|---|---|---|
| toR2 | 1/1/c1/1 | 192.168.12.1 | 30 | 192.168.12.0/30 | R2 (PE1) |
Router R2
| Interface Name | Port ID | IPv4 Address | Prefix Length | Subnet | Neighbor |
|---|---|---|---|---|---|
| toR1 | 1/1/c1/1 | 192.168.12.2 | 30 | 192.168.12.0/30 | R1 (CE1) |
| toR3 | 1/1/c2/1 | 192.168.23.1 | 30 | 192.168.23.0/30 | R3 (P1) |
| toR4 | 1/1/c3/1 | 192.168.24.1 | 30 | 192.168.24.0/30 | R4 (P2) |
Router R3
| Interface Name | Port ID | IPv4 Address | Prefix Length | Subnet | Neighbor |
|---|---|---|---|---|---|
| toR2 | 1/1/c1/1 | 192.168.23.2 | 30 | 192.168.23.0/30 | R2 (PE1) |
| toR5 | 1/1/c2/1 | 192.168.35.1 | 30 | 192.168.35.0/30 | R5 (PE2) |
Router R4
| Interface Name | Port ID | IPv4 Address | Prefix Length | Subnet | Neighbor |
|---|---|---|---|---|---|
| toR2 | 1/1/c1/1 | 192.168.24.2 | 30 | 192.168.24.0/30 | R2 (PE1) |
| toR5 | 1/1/c3/1 | 192.168.45.1 | 30 | 192.168.45.0/30 | R5 (PE2) |
Router R5
| Interface Name | Port ID | IPv4 Address | Prefix Length | Subnet | Neighbor |
|---|---|---|---|---|---|
| toR3 | 1/1/c2/1 | 192.168.35.2 | 30 | 192.168.35.0/30 | R3 (P1) |
| toR4 | 1/1/c3/1 | 192.168.45.2 | 30 | 192.168.45.0/30 | R4 (P2) |
| toR6 | 1/1/c1/1 | 192.168.56.1 | 30 | 192.168.56.0/30 | R6 (CE2) |
Router R6
| Interface Name | Port ID | IPv4 Address | Prefix Length | Subnet | Neighbor |
|---|---|---|---|---|---|
| toR5 | 1/1/c1/1 | 192.168.56.2 | 30 | 192.168.56.0/30 | R5 (PE2) |
Configuration
Router R1 (CE1)
edit-config global
/configure system name "R1 (CE1)"
/configure card 1 card-type iom-1
/configure card 1 mda 1 mda-type me6-100gb-qsfp28
/configure port 1/1/c1 connector breakout c1-100g
/configure port 1/1/c1 admin-state enable
/configure port 1/1/c1/1 admin-state enable
/configure port 1/1/c1/1 ethernet mode hybrid
/configure router interface "system" admin-state enable
/configure router interface system ipv4 primary address 10.100.1.1
/configure router interface system ipv4 primary prefix-length 32
/configure router interface "toR2" admin-state enable
/configure router interface "toR2" ipv4 primary address 192.168.12.1
/configure router interface "toR2" ipv4 primary prefix-length 30
/configure router interface "toR2" port 1/1/c1/1:0
commit
Router R2 (PE1)
edit-config global
/configure system name "R2 (PE1)"
/configure card 1 card-type iom-1
/configure card 1 mda 1 mda-type me6-100gb-qsfp28
/configure port 1/1/c1 connector breakout c1-100g
/configure port 1/1/c2 connector breakout c1-100g
/configure port 1/1/c3 connector breakout c1-100g
/configure port 1/1/c1 admin-state enable
/configure port 1/1/c2 admin-state enable
/configure port 1/1/c3 admin-state enable
/configure port 1/1/c1/1 admin-state enable
/configure port 1/1/c1/1 ethernet mode hybrid
/configure port 1/1/c2/1 admin-state enable
/configure port 1/1/c2/1 ethernet mode hybrid
/configure port 1/1/c3/1 admin-state enable
/configure port 1/1/c3/1 ethernet mode hybrid
/configure router interface "system" admin-state enable
/configure router interface system ipv4 primary address 10.100.1.2
/configure router interface system ipv4 primary prefix-length 32
/configure router interface "toR1" admin-state enable
/configure router interface "toR1" ipv4 primary address 192.168.12.2
/configure router interface "toR1" ipv4 primary prefix-length 30
/configure router interface "toR1" port 1/1/c1/1:0
/configure router interface "toR3" admin-state enable
/configure router interface "toR3" ipv4 primary address 192.168.23.1
/configure router interface "toR3" ipv4 primary prefix-length 30
/configure router interface "toR3" port 1/1/c2/1:0
/configure router interface "toR4" admin-state enable
/configure router interface "toR4" ipv4 primary address 192.168.24.1
/configure router interface "toR4" ipv4 primary prefix-length 30
/configure router interface "toR4" port 1/1/c3/1:0
commit
Router R3 (P1)
edit-config global
/configure system name "R3 (P1)"
/configure card 1 card-type iom-1
/configure card 1 mda 1 mda-type me6-100gb-qsfp28
/configure port 1/1/c1 connector breakout c1-100g
/configure port 1/1/c2 connector breakout c1-100g
/configure port 1/1/c1 admin-state enable
/configure port 1/1/c2 admin-state enable
/configure port 1/1/c1/1 admin-state enable
/configure port 1/1/c1/1 ethernet mode hybrid
/configure port 1/1/c2/1 admin-state enable
/configure port 1/1/c2/1 ethernet mode hybrid
/configure router interface "system" admin-state enable
/configure router interface system ipv4 primary address 10.100.1.3
/configure router interface system ipv4 primary prefix-length 32
/configure router interface "toR2" admin-state enable
/configure router interface "toR2" ipv4 primary address 192.168.23.2
/configure router interface "toR2" ipv4 primary prefix-length 30
/configure router interface "toR2" port 1/1/c1/1:0
/configure router interface "toR5" admin-state enable
/configure router interface "toR5" ipv4 primary address 192.168.35.1
/configure router interface "toR5" ipv4 primary prefix-length 30
/configure router interface "toR5" port 1/1/c2/1:0
commit
Router R4 (P2)
edit-config global
/configure system name "R4 (P2)"
/configure card 1 card-type iom-1
/configure card 1 mda 1 mda-type me6-100gb-qsfp28
/configure port 1/1/c1 connector breakout c1-100g
/configure port 1/1/c3 connector breakout c1-100g
/configure port 1/1/c1 admin-state enable
/configure port 1/1/c3 admin-state enable
/configure port 1/1/c1/1 admin-state enable
/configure port 1/1/c1/1 ethernet mode hybrid
/configure port 1/1/c3/1 admin-state enable
/configure port 1/1/c3/1 ethernet mode hybrid
/configure router interface "system" admin-state enable
/configure router interface system ipv4 primary address 10.100.1.4
/configure router interface system ipv4 primary prefix-length 32
/configure router interface "toR2" admin-state enable
/configure router interface "toR2" ipv4 primary address 192.168.24.2
/configure router interface "toR2" ipv4 primary prefix-length 30
/configure router interface "toR2" port 1/1/c1/1:0
/configure router interface "toR5" admin-state enable
/configure router interface "toR5" ipv4 primary address 192.168.45.1
/configure router interface "toR5" ipv4 primary prefix-length 30
/configure router interface "toR5" port 1/1/c3/1:0
commit
Router R5 (PE2)
edit-config global
/configure system name "R5 (PE2)"
/configure card 1 card-type iom-1
/configure card 1 mda 1 mda-type me6-100gb-qsfp28
/configure port 1/1/c1 connector breakout c1-100g
/configure port 1/1/c2 connector breakout c1-100g
/configure port 1/1/c3 connector breakout c1-100g
/configure port 1/1/c1 admin-state enable
/configure port 1/1/c2 admin-state enable
/configure port 1/1/c3 admin-state enable
/configure port 1/1/c1/1 admin-state enable
/configure port 1/1/c1/1 ethernet mode hybrid
/configure port 1/1/c2/1 admin-state enable
/configure port 1/1/c2/1 ethernet mode hybrid
/configure port 1/1/c3/1 admin-state enable
/configure port 1/1/c3/1 ethernet mode hybrid
/configure router interface "system" admin-state enable
/configure router interface system ipv4 primary address 10.100.1.5
/configure router interface system ipv4 primary prefix-length 32
/configure router interface "toR3" admin-state enable
/configure router interface "toR3" ipv4 primary address 192.168.35.2
/configure router interface "toR3" ipv4 primary prefix-length 30
/configure router interface "toR3" port 1/1/c2/1:0
/configure router interface "toR4" admin-state enable
/configure router interface "toR4" ipv4 primary address 192.168.45.2
/configure router interface "toR4" ipv4 primary prefix-length 30
/configure router interface "toR4" port 1/1/c3/1:0
/configure router interface "toR6" admin-state enable
/configure router interface "toR6" ipv4 primary address 192.168.56.1
/configure router interface "toR6" ipv4 primary prefix-length 30
/configure router interface "toR6" port 1/1/c1/1:0
commit
Router R6 (CE2)
edit-config global
/configure system name "R6 (CE2)"
/configure card 1 card-type iom-1
/configure card 1 mda 1 mda-type me6-100gb-qsfp28
/configure port 1/1/c1 connector breakout c1-100g
/configure port 1/1/c1 admin-state enable
/configure port 1/1/c1/1 admin-state enable
/configure port 1/1/c1/1 ethernet mode hybrid
/configure router interface "system" admin-state enable
/configure router interface system ipv4 primary address 10.100.1.6
/configure router interface system ipv4 primary prefix-length 32
/configure router interface "toR5" admin-state enable
/configure router interface "toR5" ipv4 primary address 192.168.56.2
/configure router interface "toR5" ipv4 primary prefix-length 30
/configure router interface "toR5" port 1/1/c1/1:0
commit
Verification
Step 1: Verify Port Operational Status
Check that all active physical ports across the routers are enabled and linked. Ensure the Admin State is Up and the link state shows active for each connected port (e.g., port 1/1/c1/1).
Step 2: Verify Router Interfaces
Verify that both the system loopback and all physical interfaces are configured with the correct IP addresses and are administratively up, with physical links showing operational status as active.
Step 3: Test Direct Physical Link Reachability (Ping)
From each router, verify direct layer 2 and layer 3 link integrity by pinging the directly connected IP address of your neighbors (for example, pinging R1’s interface IP from R2). This should yield 0% packet loss and successful round-trip replies before any routing protocols are introduced.
Step 4: Test Remote Loopback Reachability (Expected Failure)
Before we configure routing (OSPF), let’s attempt to ping a non-direct system loopback address across the network (for example, targeting R6’s loopback IP from R2).
Note: This failure is completely expected at this stage. It shows that setting up physical interfaces only grants local subnet reachability, paving the way for the upcoming OSPF configurations to solve the missing path.