Iteration

You'll struggle to come up with something truly dynamic (and elegant) in one cell without use of VBA (UDF) and/or 3rd party add-in like morefunc.xll (MCONCAT function)

In UDF terms, the below stored in a Module

Option Explicit
Option Compare Text
Function Switches(strRept As String, rngRept As Range, Optional strDelim As String) As String
Dim lngRept As Long
If strDelim = "" Then strDelim = ","
For lngRept = 1 To rngRept.Value Step 1
    Switches = Switches & strDelim & Replace(strRept, "[X]", lngRept)
Next lngRept
Switches = Replace(Switches, strDelim, "", 1, 1)
End Function

in a Macro Enabled file can be used along lines of:

B2: =SWITCHES("GigabitEthernet, [X]/0/1 - 48",$A2)

where [X] denotes the placeholder position

If you wanted to use an alternative delimiter (to comma) you can explicitly pass the otherwise optional 3rd argument, eg to use :

B2: =SWITCHES("GigabitEthernet, [X]/0/1 - 48",$A2,":")

@ DonkeyOte

That worked beautifully!! Thank you so much, really appreciated! I had another scenerio I wanted to run by you...

Suppose I want the first and last elements in the string to be different from what's in between such as the following:

interface range GigabitEthernet1/0/51 - 52,GigabitEthernet2/0/49 - 52,GigabitEthernet3/0/49 - 52,GigabitEthernet4/0/51 - 52

Thanks again,

Anne

Not quite sure I follow... you're altering the first element in sequence (ie 1 to n) but the 2nd appears perhaps random (?) - ie how do you determine logically as to whether or not the final element should be 49/51 ? (is it only first/last should be 51 ?)