Adding parameters from grok to syslog output

[karasmeitar]

Hi All,
I'm trying to add my syslog ip server from in my grok filter and consume it in my logstash syslog output.
In the filter section i'm adding the following:
mutate {
add_field => {
"IP" => "10.10.10.1"
"port" => 516
}
}

in the output i'm adding:
syslog {
host => "%{IP}"
port => "%{port}"
}

I have two problems with this configuration:

1. with the type of the port.. i'm getting error that it should be a number
2. with the IP, when i changed the port manually to 512 i'm still not getting the logs.

Thanks for your help.