Today we have an MX204 and we announced our AS using Juniper, but we also have partnership with another internet provider that has another AS. This other AS has much less client and a much smaller network traffic, and we only need a static route, we control the ads and we received full routing in the main AS.

I was curious if it is possible to have the two announcing them within the Junos, the equipment handles a lot of network traffic and we could eliminate another Mikrotik from the network.

If possible and someone has some example of configuration I will be very grateful.

Sorry for the bad English.


There are several ways to do this.

Logical Systems (LSYS)

Logical Systems are a means of segmenting your Junos router into multiple logical systems, which have separate configurations, routing protocols, and interfaces.

This is similar to having separate routers that happen to share a physical chassis. The neighboring routers, such as your BRAS, have no idea there is any overlap among the networks.

To connect the LSYS together look into Logical Tunnel (lt-) interfaces.


VRFs / virtual-routers / L3VPNs are another means. You could configure the smaller network as a VRF or L3VPN.

You can do this without support for L3VPN on your BRAS by treating it as a CE device. It can have ordinary routing protocol sessions for e.g. BGP or OSPF.

To share transit or peering, you can leak routes between the main routing table (called master by Junos) and the VRF/L3VPN table(s).

     |      |
      \     /
      /     \
     /      PE
    /        \
   |         CE
   |          |
  AS1        AS2
 Custs       BRAS

In truth, though, if your goal is to consolidate the equipment of the other "ISP" into your own, what you should really do is merge them into a single AS. This will simplify your network management in the future. It's not clear why you don't want to do that, but I see you've commented that you don't.

  • Thanks for the answer, I believe I have been able to understand, we have a Huawei Ne40 bras and we will need the license to put VRF on it as well. It would really be interesting together the AS, but I believe it will not occur. At the moment, to follow no stops in the provider, VRF will be the best solution. – Marcos Max Nov 24 '20 at 18:04
  • I made some edits that might help you work out the options for connecting to the BRAS. You don't necessarily need L3VPN/VRF capability on it. I wouldn't suggest that unless you think there's a particular advantage -- no reason to make it more complex. – Jeff Wheeler Nov 24 '20 at 18:14
  • If you can pass me some example, it would really help really. – Marcos Max Nov 24 '20 at 18:17

The best way is to ask the smaller ISP to modify their configuration to accept your AS number.

  • This will not be possible because we sell different plans and if using our AS will have to change several other things, but I know that in other equipment such as Huawei it is possible to make this configuration of two AS on the same equipment. – Marcos Max Nov 24 '20 at 15:58

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