Advanced ONIE DHCP examples for Dell Enterprise SONIC

Amazing things can be done with ONIE. Out with manual and error prone NOS instllation and in with 'everything is a code' approach. These examples are tested in real world scenarions and their aim is to save you precious time and repetitive lines of code.

Prerequsites

1. ISC-DHCP server
2. Configure Vendor-Identifying Vendor-Specific Information (VIVSO)

ISC-DHCP server

You can use provided docker file to buil your own ISC-DHCP server, or just download the dhcpd.conf and hosts files and tweak them to suit your needs.

Please note that the docker image uses host networking, so you need to have an interface with same subnet configured on the host that runs the container:

3: ens192: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:50:56:b4:5a:02 brd ff:ff:ff:ff:ff:ff
    inet 192.168.50.1/24 brd 192.168.50.255 scope global ens192
       valid_lft forever preferred_lft forever
    inet6 fe80::250:56ff:feb4:5a02/64 scope link
       valid_lft forever preferred_lft forever

You can then launch the docker image with the docker-compose command and provided docker-compose.conf file:

docker-compose up -d

ISC-DHCP VIVSO configuration

We need to create ONIE namespace so we can parse the options and send responses back to requests made by individual instances.

# Create an option namespace called ONIE
option space onie code width 1 length width 1;

# Define the code names and data types within the ONIE namespace
option onie.installer_url code 1 = text;
option onie.updater_url   code 2 = text;
option onie.machine       code 3 = text;
option onie.arch          code 4 = text;
option onie.machine_rev   code 5 = text;

# Package the ONIE namespace into option 125
option space vivso code width 4 length width 1;
option vivso.onie code 42623 = encapsulate onie;
option vivso.iana code 0 = string;
option op125 code 125 = encapsulate vivso;

Source ONIE VIVSO

Install same ONIE image on a group of switch models (aka Match Vendor Class Identifier)

Since ISC-DHCP doesn't support wildcards * or regular expressions, we need to use vendor-class-identifier and tell it the length of the string we are looking for.

In this example, string onie_vendor:x86_64-dellemc_n3248 is 32 bytes long and matches ALL N3200 platforms, such as N3248TE, N3248PXE, N3248X. Your can use this property to match other platfroms in same way. See the table Dell Enterprise ONIE platforms for details.

class "N3200" {
  # Limit the matching to a request we know originated from ONIE
  match if substring(option vendor-class-identifier, 0, 32) = "onie_vendor:x86_64-dellemc_n3248";

  # Required to use VIVSO
  option vivso.iana 01:01:01;

  # N series SONIC image
  option onie.installer_url = "http://192.168.50.1/onie-installer-n3200";

}

Source ONIE Match Vendor Class Identifier

Install same ONIE image on a given switch model (aka VIVSO)

In this example we pass same image to same switch model, each model can have a different image.

class "onie-vendor-classes" {
  # Limit the matching to a request we know originated from ONIE
  match if substring(option vendor-class-identifier, 0, 11) = "onie_vendor";

  # Required to use VIVSO
  option vivso.iana 01:01:01;

  # N3248PXE
  if option onie.machine = "dellemc_n3248pxe_c3338" {
    option onie.installer_url = "http://192.168.50.1/onie-installer-n3200";
  }

  # N3248TE
  if option onie.machine = "dellemc_n3248te_c3338" {
    option onie.installer_url = "http://192.168.50.1/sonic-4.1.bin";
  }

  # Z9100
  if option onie.machine = "dellemc_z9100_c2538" {
    option onie.installer_url = "http://192.168.50.1/onie-installer";
  }
}

Source ONIE VIVSO

Dell Enterprise SONIC ONIE platforms

You can use these ONIE platform identifiers in your DHCP configuration. Please note that you would need to remove the x86_64- string in order to be able to match the switch model in onie.machine DHCP option.

Dell Technologies switch model	ONIE platform
E3248P	x86_64-dell_e3248p-r0
E3248PXE	x86_64-dell_e3248pxe-r0
S6000	x86_64-dell_s6000_s1220-r0
S6100	x86_64-dell_s6100_c2538-r0
Z9100	x86_64-dell_z9100_c2538-r0
N3248PXE	x86_64-dellemc_n3248pxe_c3338-r0
N3248TE	x86_64-dellemc_n3248te_c3338-r0
N3248X	x86_64-dellemc_n3248x_c3338-r0
S5212F	x86_64-dellemc_s5212f_c3538-r0
S5224F	x86_64-dellemc_s5224f_c3538-r0
S5232F	x86_64-dellemc_s5232f_c3538-r0
S5248F	x86_64-dellemc_s5248f_c3538-r0
S5296F	x86_64-dellemc_s5296f_c3538-r0
Z9100	x86_64-dellemc_z9100_c2538-r0
Z9264F	x86_64-dellemc_z9264f_c3538-r0
Z9332F	x86_64-dellemc_z9332f_d1508-r0
Z9432F	x86_64-dellemc_z9432f_c3758-r0