Configure Shibboleth-SP-2.3.1 with DS-1.1.3.

[Cantor, Scott]

> Session Initiator configuration  on Shibboleth-SP-2.3.1 Side: (in
> shibboleth2.xml)

2.3.1 has a critical security bug, so I hope you're not serious unless this is a backported Debian or something.

> After configuration of SP and DS, we were able to select the idp on the "Idp
> selection/discovery" page and the user is redirected to the following URL.
> But SP complaints that URL(https://mysp.mysp.net/Shibboleth.sso/Login)
> does not exist.

Then the SP isn't configured or working, irrespective of the DS. Get it working with one IdP first. If the handlerURL is returning that, things aren't really set up yet. You provided no platform information, so there's nothing else I can say about causes.
 
> Is there any additional configuration on SP ?

No.

-- Scott