Add 2 source ip addresses to switch in irule

If you want to keep the iRule as it is, just add the new IP addresses as below:

when HTTP_REQUEST {

  set srcip [IP::client_addr]
  set host [string tolower [HTTP::host]]

  switch $srcip { 
  "1.1.1.1" - 
  "2.2.2.2" -
  "66.78.30.7" {
    switch $host {
      "xyz.abc.net" {
        pool xyz.abc.net-ggi-https
      }
    }
  } 
}
}

However, your current solution needs some improvements. I'd recommend something as below that does the exact same job:

when HTTP_REQUEST {

  if { [string tolower [HTTP::host]] == "xyz.abc.net" } {
    switch [IP::client_addr] { 
      "1.1.1.1" - 
      "2.2.2.2" -
      "66.78.30.7" {
        pool xyz.abc.net-ggi-https
      }
    }
  } 
}

Recommendations: 1 - Don't define variables, unless you really have to (waste of memory) 2 - Use of the IF-statement is preferred in case of a single condition. SWITCH-statement is better when you have 3 or more conditions.