I don't think that there is a limit on the number of tables you can create but the number of routes you could have in the same, I was not able to find official documentation to confirm this so I was curious to know if you are facing some issues while trying to do this like commit error or something like that.?
Just for the reference, this is the only information I was able to find but unfortunately, it is not mentioning anything of a limited number of routing tables just says "one or more"
root# help topic routing-options rib-groups Creating Routing Table Groups
You can group together one or more routing tables to form a routing table group. Within a group, a routing protocol can import routes into all the routing tables in the group and can export routes from a single routing table.
Regards, Lil Dexx JNCIE-ENT#863
If this solves your problem, please mark this post as "Accepted Solution" so we can help others too \/
I believe the limit will be based on the number of routes that your device can support and the number of routes you are placing on each import table.
For example, say you configure a rib-group that places the entire internet routing table (let's say 800K routes), on multiple routing tables. Assume also that you RE can handle 30 million routes. that means that when you start reaching around 37 tables, you will be reaching the limitations of your RE, in terms of number of routes.
Also keep in mind that there is a limit in the number of routing-instances (VRs, VRFs), thus there is maximum number of routing tables that you can create.
There is no hard limit but practical limit would be the number of "rib-grouppable" routing-instances supported on that particular Juniper product. L2VPN and VPLS instances are not supported in rib-groups so that would leave VR, forwarding and L3VPN (VRF) instances as practically available rib-group recipients.
In terms of numbers, on high end MX with latest RE-NG the supported number of L3VPN and VR instances is 16K.
I quickly tested rib-group with 16001 instances (16K VR + inet.0) under "import-rib" stanza on JUNOS 19.4R1 and it committed just fine. I did create 16K VRs as well.
Whether You want to use rib-groups in this fashion is up to You :-), I would rather not.
From what you have all said it seems the limitation is number of routes rather than number of routing tables.
I have not come across a commit error or any issues so far but just want to make sure a solution will work before rolling it out. We are looking at advertising a few prefixes that are public, used for management devices, into a number of customer networks. The number of networks is likely to be in the tens rather than thousands and was concerned we might hit a hard limit.