IOS DHCP config question

[adil.nasser3]

Hello All,

I viewed this configuration in a home router and, while I am quite familiar with the first section of the code for creating a dhcp server on the IOS router, I have never come across code as show in the 2nd (Slingbox) and 3rd (RPS-Main) section.  From what it appears to me, it looks like static ip to mac reservations.  Can someone confirm if my thought is correct?  Also can someone explain what client-identifier are and why they are used instead of just specifying mac-addresses?

Thanks in advance,

Adil

ip dhcp pool DHCP

   network 172.16.60.0 255.255.255.0

   default-router 172.16.60.1

   domain-name example.com

   option 150 ip 10.10.24.11 10.10.8.10

   dns-server 10.10.10.3 10.10.10.2

!

ip dhcp pool Slingbox

   host 172.16.60.9 255.255.255.0

   client-identifier 0100.13b6.3262.60

   default-router 172.16.60.1

   domain-name na.example.com

   option 150 ip 10.10.24.11 10.10.8.10

   dns-server 10.10.10.3 10.10.10.2

!

ip dhcp pool RPS-Main

   host 172.16.60.10 255.255.255.0

   client-identifier 0100.24e8.00bc.3c

   default-router 172.16.60.1

   option 150 ip 10.10.24.11 10.10.8.10

   domain-name na.takatacorp.com

   dns-server 10.10.10.3 10.10.10.2

[Giuseppe Larosa]

Hello Adil,

your understanding is correct the pools Slingbox and RPS-Main are sort of subpools used to create a one to one corrispondence between a MAC address and an IP address belonging to the parent pool.

the client-identifier is a modified format that is simply 0x01 in front of the original 48bit MAC address.

The DHCP standard uses client-identifier and the meaning of that initial 0x01 should simply be standard ethernet client.

When DHCP protocol was designed other forms of LANs were present like Token Ring and FDDI with their own conventions for addressing. So it makes sense that a first byte for encoding the type of LAN technology was introduced.

Hope to help

Giuseppe