UPSTREAM VLAN + BGP CONFIGURATION JUNIPER ROUTER STEP BY STEP

UPSTREAM VLAN + BGP CONFIGURATION JUNIPER ROUTER STEP-BY-STEP , Here’s how to configure a Juniper router for an upstream connection using VLAN and BGP. This is commonly used for connecting to an ISP or a data center uplink with a VLAN tag and establishing BGP peering.

📘 Use Case Example

Interface: ae0
VLAN ID: 3920
IP Address: 10.40.4.177/31
Upstream IP: 10.40.4.176/31
Local ASN: 141460
Upstream ASN: 58682
BGP Peer IP: 10.40.4.176

🛠 Step-by-Step Juniper Upstream VLAN + BGP Configuration

1. Enter Configuration Mode

2. Configure the VLAN Interface (Layer 3 Sub-interface)

3. Configure BGP

4. Enable BGP Export/Import Policies

JunOS requires policy for route export/import in BGP.

set policy-options policy-statement L3-INT-PRI-OUT term 1 from route-filter 103.159.255.0/24 exact

set policy-options policy-statement L3-INT-PRI-OUT term 1 then as-path-prepend "141460 141460 141460 141460"

set policy-options policy-statement L3-INT-PRI-OUT term 1 then accept

set policy-options policy-statement L3-INT-PRI-OUT term 2 from route-filter 103.159.254.0/24 exact

set policy-options policy-statement L3-INT-PRI-OUT term 2 then as-path-prepend "141460 141460 141460 141460"

set policy-options policy-statement L3-INT-PRI-OUT term 2 then accept

set policy-options policy-statement L3-INT-PRI-OUT term 1000 then reject

5. Commit Configuration

✅ Summary of Key Commands

set interfaces ae0 unit 3920 description L3-3920-INT

set interfaces ae0 unit 3920 vlan-id 3920

set interfaces ae0 unit 3920 family inet address 10.40.4.177/31

set policy-options policy-statement L3-INT-PRI-IN term 1 from route-filter 0.0.0.0/0 exact

set policy-options policy-statement L3-INT-PRI-IN term 1 then local-preference 250

set policy-options policy-statement L3-INT-PRI-IN term 1 then accept

set policy-options policy-statement L3-INT-PRI-IN term 1000 then reject

set policy-options policy-statement L3-INT-PRI-OUT term 1 from route-filter 103.159.255.0/24 exact

set policy-options policy-statement L3-INT-PRI-OUT term 1 then as-path-prepend "141460 141460 141460 141460"

set policy-options policy-statement L3-INT-PRI-OUT term 1 then accept

set policy-options policy-statement L3-INT-PRI-OUT term 2 from route-filter 103.159.254.0/24 exact

set policy-options policy-statement L3-INT-PRI-OUT term 2 then as-path-prepend "141460 141460 141460 141460"

set policy-options policy-statement L3-INT-PRI-OUT term 2 then accept

set policy-options policy-statement L3-INT-PRI-OUT term 1000 then reject

set protocols bgp group L3-INT-PRI-3920 type external

set protocols bgp group L3-INT-PRI-3920 neighbor 10.40.4.178 description L3-INT-PRI-3920

set protocols bgp group L3-INT-PRI-3920 neighbor 10.40.4.178 local-address 10.40.4.177

set protocols bgp group L3-INT-PRI-3920 neighbor 10.40.4.178 import L3-INT-PRI-IN

set protocols bgp group L3-INT-PRI-3920 neighbor 10.40.4.178 export L3-INT-PRI-OUT

set protocols bgp group L3-INT-PRI-3920 neighbor 10.40.4.178 peer-as 58629