# cJunosEvolved Lab — Quick Guide

Three Junos routers on Fedora using Containerlab. Works on AMD or Intel.

## 1. Install Docker and Containerlab

```bash
# Docker
sudo dnf install dnf-plugins-core
sudo dnf config-manager addrepo --from-repofile=https://download.docker.com/linux/fedora/docker-ce.repo
sudo dnf install docker-ce docker-ce-cli containerd.io
sudo systemctl enable --now docker

# Containerlab
bash -c "$(curl -sL https://get.containerlab.dev)"
```

Verify:
```bash
docker --version
containerlab version
```

## 2. Get the cJunosEvolved image

Download from https://www.juniper.net/us/en/dm/vjunos-labs.html (free, no login). Look for `cJunosEvolved-XX.X.X-EVO.tar.gz`.

Load it:
```bash
sudo docker load -i ~/Downloads/cJunosEvolved-25.4R1.13-EVO.tar.gz
sudo docker images | grep cjunos
```

Note the exact image tag (e.g. `cjunosevolved:25.4R1.13-EVO`).

## 3. Create the topology

```bash
mkdir -p ~/junos-lab && cd ~/junos-lab
```

Save as `~/junos-lab/topology.clab.yml` — adjust `image:` to match your tag:

```yaml
name: junos-triangle

topology:
  kinds:
    juniper_cjunosevolved:
      image: cjunosevolved:25.4R1.13-EVO

  nodes:
    rt1: { kind: juniper_cjunosevolved }
    rt2: { kind: juniper_cjunosevolved }
    rt3: { kind: juniper_cjunosevolved }

  links:
    - endpoints: ["rt1:et-0/0/0", "rt2:et-0/0/0"]
    - endpoints: ["rt2:et-0/0/1", "rt3:et-0/0/0"]
    - endpoints: ["rt1:et-0/0/1", "rt3:et-0/0/1"]
```

## 4. Deploy

```bash
cd ~/junos-lab
sudo containerlab deploy -t topology.clab.yml
```

Wait ~5 minutes for Junos to boot inside each container. Watch one if you want:
```bash
sudo docker logs -f clab-junos-triangle-rt1
```
When you see `rt1 login:`, it's ready. Ctrl+C to stop following.

## 5. Connect to a router

Two-step: drop into the container's bash, then telnet to the inner Junos console on port 8601.

```bash
sudo docker exec -ti clab-junos-triangle-rt1 bash
# now inside the container:
telnet 127.0.0.1 8601
```

Press Enter to redraw the prompt. Login as `root` (blank password). Type `cli` for the Junos CLI.

**Disconnect cleanly:**
- From Junos CLI back to bash: `exit`
- From telnet: `Ctrl-]` then type `quit`
- From container bash to host: `exit` or Ctrl-D

For rt2 use `clab-junos-triangle-rt2`, for rt3 use `clab-junos-triangle-rt3`.

## 6. Daily commands

```bash
cd ~/junos-lab

# Boot the lab
sudo containerlab deploy -t topology.clab.yml

# See running state and IPs
sudo containerlab inspect -t topology.clab.yml

# Visual topology graph (browser)
sudo containerlab graph -t topology.clab.yml

# Tear down
sudo containerlab destroy -t topology.clab.yml
```

`inspect` only works from inside `~/junos-lab` (the topology.clab.yml needs to be findable). Or use `sudo containerlab inspect --all` from anywhere.

## Troubleshooting

| Problem | Fix |
|---|---|
| `Failed to fetch http(s) resource` | You ran the command outside `~/junos-lab`. `cd` there first or use absolute path. |
| Login prompt doesn't appear | Junos still booting. Wait 5 min total from deploy, mash Enter at the telnet prompt. |
| `telnet: command not found` inside container | Use `nc 127.0.0.1 8601` instead. |
| Container not starting | `sudo docker logs clab-junos-triangle-rt1` shows why. |
| Stuck after Ctrl-C in `docker logs` | That's just stopping the log follow — container is fine. |