Add more descriptive instructions

README.md

@@ -4,8 +4,11 @@ Small script synchronizes phpipam hosts with pi-hole resolvers.
 
 ## Use case
 
-Phpipam considered source of truth for DNS resolution. Network admins create hostnames in phpipam. 
-Pihole used as a DNS-server. 
+Phpipam considered to be a source of truth for DNS resolution. 
+* Network admins create hostnames in phpipam. 
+* Pihole used as a DNS-server.
+* (optional) Cisco router acts as a DHCP-server
+
 To synchronize phpipam hostanmes with pihole DNS-resolver 
 ```
 phpipamsync get pi-hole
@@ -26,3 +29,61 @@ pi_hole: /home/ikuchin/docker/pi.hole/etc-pihole/custom.list    # full path to p
 ```
 
 **ATTENTION** pi-hole custom file will be rewritten, not appended.
+
+## phpipam API token
+
+To generate API topken, in phpipam go to Administration -> API -> Create API token. 
+
+* Type - SSL with App code token
+* App permission - Read
+
+Important:  HTTPS access should be enabled to phpipam
+
+## Cisco DHCP config
+
+To generate DHCP config snippet for Cisco router configuration 
+
+```
+phpipamsync get cisco-dhpc
+```
+
+Once snippet generated it can be copy/paste-ed to actual router configuration. There is no integration between phpipamsync and router.
+
+## Examples
+
+### DNS resolution
+
+```
+e:\docs\src\go\phpipamsync>nslookup tesla.home
+...
+Non-authoritative answer:
+Name:    tesla.home
+Address:  192.168.168.49
+
+e:\docs\src\go\phpipamsync>nslookup 192.168.168.49
+...
+Name:    tesla.home
+Address:  192.168.168.49
+```
+
+### Cisco IOS DHCP config
+
+ClientID generated from either of options below:
+* MAC address (by adding prefix 01.....)
+* Custom field named ClientID ( Administration -> Custom fields -> Custom IP addresses fields )
+
+```
+$ phpipamsync get cisco-dhcp
+
+ip dhcp pool fridge
+ host 192.168.251.13 255.255.255.0
+ client-identifier 0170.2c1f.3ed2.cb
+ default-router 192.168.251.1
+!
+ip dhcp pool tesla
+ host 192.168.168.49 255.255.255.0
+ client-identifier 014c.fcaa.8ec6.62
+ default-router 192.168.251.1
+!
+```
+