KNX/EIB ABB Router IPR/s 2.1 -Routing and coupling question

[Nitin]

Hello
I have an existing setup with one IP/R S2.1(Its a KNX router) with multiple devices given address 1.x.x
The original installer gave 1.1.200 to the IP/R S2.1, which gave me unknown headaches when i tried to interface with Homeassistant (only multicast will work). I had to turn on routing for both 1-13 and 14-15 for it to accept from HA. The Ip of this router is 192.168.0.7 - with no gateway (so that my guests who are on 192.168.2.x donot reach it. My HA is at 192.168.3.x and reaches it my multicast forwarding at the switch level)

Now, i would like to expand to my glassroom (which is connected to house IP base by repeater). While planning, I have multiple roadblocks and I need help. As most of you speak German natively, I have provided my problems as points, which may be easier to reply and understand.
My plan is

192.168.0.7(Router 1- Inside Home) -------1.x.x GA is 1/0/0 to 4/0/0
192.168..0.8(Router 2- Outside home - linked by wireless link) --------2.x.x GA is 5/0/0 to 5/14/x


1. homeasssistant can have only one tunnel connection. Does that mean I will have to use multicast only? This is going to be a problem on wifi links.
2. I am going to use the router 2 as Line coupler. Assigned 2.0.0 address to it. Is that a correct strategy? Should i change my inside home router to 1.0.0 so that it becomes a coupler too. These both have IP as base line. Then where do I tunnel to (from HA)
3. How will the HA reach the copler? Will KNX router (1.1.200 - which is inside home) send telegrams on behalf of HA to 2.0.0?)

Please help.
PS - My second part (which is connected by wifi link - is completely on planning stage - so can be changed. There are only 4 actors on this line. But my home iside has around 40 actors - so not possible to change(too much work).

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[meti]

Your routers should use either 1.0.0 and 2.0.0 or 1.1.0 and 1.2.0.
It doesn't really matter what GA ranges you use in one or the other line. You can happily mix those.

If you connect to one line via tunnelling, telegrams can still reach the other line via the router - that's its job - given the filter tables / routing rules are set up correctly.

[Nitin]

So, I should plan like this(?- its a question)
1. Reprogram my inside home router to 1.0.0. Since ETS know the routing table now - KNX->LAN is filter and LAN->KNX is filter.

2. Assign my router connected via Wifi as 2.0.0. Filtering on both KNX and LAN sides.

3. HA will tunnel into 1.0.0. If it wants to send telegram to 5/x/x, it has no idea and will send it to 1.0.0. This 1.0.0 router will then use IP backbone and send it to 2.0.0(this is very confusing - how does it know 5/x/x GA is with 2.0.0)

4. 2.0.0 when it recvs telegram from 5/x/x, it will send it to 1.0.0? 1.0.0 then send it to HA?

Its very confusing and not analogous to IP addressing at all.

[meti]

If you do 1) you'll have to change all devices addresses on that line to 1.0.x too.

3) Yes, if 5/x/x is available on 1.0 line. That's what filter tables are for. If not it will not forward it. You can use dummies or assign GAs to tunnel endpoints to keep filter tables up to date.

4) Yes, if filter table.

5) Yes, it is not.

[Nitin]

Thank you for clarifying my doubts.
If you do 1) you'll have to change all devices addresses on that line to 1.0.x too. <-I meant 1.1.0

Since all my existing address are 1.1.1 to 1.1.200 will changing this router address from 1.1.200 to 1.1.0 make it a coupler? (I didnot take any course in KNX so only thing I know is that .0 are the most important addresses and can turn a router into coupler and vice versa)

for (3), 5/x/x is NOT on 1.1.x. Its only available behind the wifi connected 2.1.0(Hopefully my diag above is readable).
So, to route 5/x/x and send it to 2.1.0 coupler, I need to make a dummy address in this group (say 5/1/250 and 5/2/250) and attach it to my line which has 1.1.0?

[meti]

If you leave the first router on 1.1.0 (1.1.200 is not a valid option for a router) then your 1. area has to be IP. So you can use 1.2.0 for the second router and 1.2.x for its TP devices.

I didnot take any course in KNX

Now may be a good time to look into that. At least read some topology basics https://www.knx.fi/doc/esitteet/KNX-Basics_en.pdf

I need to make a dummy address in this group

Not a dummy address, but a dummy device you assign all groups you want routed. Have a look here https://support.knx.org/hc/en-us/art...-Filter-tables

[Nitin]

As an update -
I renamed 1.1.200 as 1.1.0. It automatically gave me option of 1.x.x as marking it as base. I set the base as IP.
I will now rename the outside home as 1.2.x (The router being 1.2.0)

Now both 1.1.0 router and 1.2.0 router "know" that they are connected to each other via IP. This partially solves my mystery of how routing will take place(coming from IP world - I thought of "learning routes"). The way KNX routing works is that it KNOWS beforhand the full toplology and therefore will know where to route the GA to certain router.
Much clearer now.
Thank you.

[Klaus Gütter]

No, the routers do not know to which other router to forward a group telegram. The backbone communication is multicast, not point-to-point. Every IP router sees all the communication on the backbone and decides according to a filter table which of the GA need to be forwarded to the TP side.