isisd not generating L2 LSP correctly

[ipinlnd]

Hi,
Having tested isisd with cisco, I found out that there's a difference in the behavior of adding routes to L2 LSPs between them. Apparently, cisco adds every route it gets from a Level-1 LSP, and adds it to its own Level-2 LSP. For example, if we have two cisco routers, R1 and R2, which are both neighbors on L1 and L2, when R1 sends two LSPs (L1 and L2) to R2; R2 receives these two LSPs, saves them, and then adds the routes advertised by R1 as Level-1, and adds them to its own L2 LSP (I don't know if that example made the situation any clearer). But FRR doesn't have the same behavior. In FRR, we don't add any routes to own_lsp other than addressed that are assigned on interfaces who are running the same instance.
Now my question is (If I'm not wrong and we don't actually support this), is cisco working correctly in this situation, and if so, what are your suggestions on implementation methods for this feature?

Thank you

[ipinlnd]

Or another possibility is that R2 doesn't get routes from R1's Level-1 LSP, It only puts its own known ISIS routes inside its own_lsp which makes more sense 😬

[cfra]

The behavior which you are asking for is currently not yet implemented. It's defined in https://tools.ietf.org/html/rfc1195#section-3.2

To implement this, one would probably need to:
a) Add the option to configure summarization prefixes
b) Add code that gets executed after L1 SPF to check whether reachable routes changed, and if yes
propagate that into L2 LSP according to a)

I have added it to the feature requests page for now.