Configuring DHCP Settings

This article discusses how to use the Cato Cloud as the DHCP server for network ranges and how to configure DHCP options for the entire account and groups.

Overview of DHCP in Cato Networks

After you define the DHCP ranges in the Cato Management Application, the Cato's DHCP server in the Cato Cloud assigns IP addresses to clients. You can also choose to use Cato as the DHCP relay agent for a local DHCP server in your organization.

You can configure the following DHCP settings for the network segments in a site: DHCP range, DHCP lease time, DHCP relay, and disabling DHCP. For example, to configure a specific DHCP range that is only used for a Guest WiFi VLAN in the corporate HQ. You can also define a default DHCP setting for the entire account and then apply it to the network ranges.

Configuring the Cato Cloud as the DHCP Server

When you configure a network range to use the Cato Cloud as the DHCP server for your account, each PoP assigns IP addresses and network parameters to the clients and hosts that use it to connect to the Cato Cloud.

The hosts behind the site, receive their IP addresses from the DHCP IP range for the network segment in that site. Make sure that the Gateway IP address isn’t included in the DHCP range.

For hosts that require a static IP address, such as a network printer, you can assign the static IP address in two ways:

  1. Manually configure the static IP address on the host. Make sure that the configured IP address isn't within the DHCP range for the network segment.

  2. Use the Cato DHCP server to allocate a static IP address for the host. With this option, the Cato DHCP server reserves the IP address for the hosts and allocates this IP address with an infinite DHCP lease time. Make sure that this IP address is within the DHCP IP address range for that network segment.

    For more about configuring a static IP and DHCP reservation for a host, see Defining Hosts for a Site.

You can define one of the following DHCP server settings for each Native Range and VLAN Range within a site:

  • Account Default - the network uses the settings for the account that are configured in the DHCP Relay section. If this section isn't configured, then Cato does NOT provide DHCP services for this network range.

  • DHCP Range - enter an IP range that is assigned by the Cato DHCP server. Use this option when you want to use Cato as the DHCP server.

  • DHCP Relay - select the DHCP relay group that you previously defined.

    The DHCP Relay option is only available for X1500, X1700 Sockets, and ESX vSockets with Socket version 10.0 or higher.

For more about DHCP relays and Cato, see Configuring Cato as the DHCP Relay.

Configuring the DHCP Range for a Network Segment

For each network range, define the DHCP IP address range for the network segments in that site in one of the following formats:

  • Range of IP addresses - 192.0.2.10-192.0.2.20

  • Subnet (CIDR) - 192.0.2.0/24

You can customize the DHCP lease time for a network segment. For more information about DHCP lease time, see below: Configuring the DHCP Lease Time For the Account.

To define the DHCP range for a network segment:

  1. From the navigation menu, click Network > Sites and select the site.

  2. From the navigation menu, click Site Configuration > Networks.

  3. In the DHCP Settings column, click the network range.

    The Edit IP Range panel opens.

    DHCP_Lease_Network_Range.png
  4. Configure the DHCP range for the network range:

    1. From the DHCP Range Type drop-down menu, select DHCP Range.

    2. Enter the DHCP Range of IP addresses that the Cato DHCP server can assign.

      You can either use CIDR or the first and last IP address of the range with a dash. For example, 10.11.1.0/28 or 10.11.1.5-10.11.1.10

  5. (Optional) Customize the DHCP lease time for this network range:

    1. In the DHCP Lease Time section, select Override Account Settings.

    2. Configure the custom Lease Time.

  6. Click Apply. The Edit IP Range panel closes.

  7. Click Save. The changes to the network range are saved.

Configuring the DHCP Lease Time For the Account

By default, Cato DHCP Server allocates IP addresses to DHCP clients with a lease time of 72 hours. You can overwrite the default lease time for IP allocations for the entire account (and also for specific site network ranges). The DHCP lease time for a network range takes priority over the lease time for the account.

DHCP_Lease_Account.png

To configure the DHCP lease time for the account:

  1. From the navigation menu, click Network > DHCP.

  2. Select or expand the DHCP Lease tab or section.

  3. Set the DHCP Lease Time that the allocated IP addresses are valid for.

  4. Click Save.

Cato DHCP Lease Timers

The following table shows details about lease times for the Cato DHCP server.

Description

Time Value

The default DHCP lease time.

After the lease expires, the IP address returns to the pool, regardless of the host activity. There's no grace period after the lease expires.

Halfway through the lease time, the client may extend its lease which will reset the lease expiration timer.

72 hours

Amount of time that a static IP address reported via DHCPINFORM is reserved.

48 hours + 6 hour grace time

For cases where the host is inactive and the IP address was not originally allocated by the Cato DHCP server. The IP address remains reserved as long as the host is active and it goes back to the pool after 6 hours of inactivity.

6 hours

Amount of time that an offered IP address is reserved.

30 seconds

Configuring DHCP Options for the Account and Groups

DHCP options lets you define custom DHCP host configuration parameters for your DHCP clients. You can configure DHCP options for groups (highest precedence) or for the entire account (lowest precedence). The options are applied according RFC 2132 and other relevant RFCs.

Note

Notes:

  • If you use the Cato Cloud as a DHCP relay instead of the DHCP server:

    • For network ranges with DHCP Range option, then the DHCP options configured in the Cato Management Application are applied

    • For network ranges with Account Default option, then the DHCP relay settings are used and the DHCP options configured in the Cato Management Application are ignored

    • For groups, the DHCP options configured in the Cato Management Application are ignored

  • The DHCP options aren't applied to Cato SDP Clients.

To configure the DHCP options:

  1. Edit the DHCP options for a specific group, or for the entire account:

    • For groups - From the navigation menu, click Assets > Groups and select the group. Then, from the navigation menu, select DHCP Option.

    • For the entire account - From the navigation menu, click Network > DHCP and then select the DHCP Options tab.

  2. Click the New button.

    The New DHCP Option panel opens.

  3. Enter a Name, and the DHCP Option Number.

  4. Configure the specific settings for the DHCP option:

    1. Select the Type of data for the option: ASCII, HEX, or IP address.

    2. Enter the Data value.

      For multiple Data values, you can enter several values separated by commas.

  5. Click Apply. The New DHCP Option panel closes and the option is added to the screen.

  6. Click Save. The DHCP option is applied to the group or the account.

Working with Hierarchy for DHCP Options

You can configure the DHCP options on different objects in the Cato Management Application, for example: settings for the entire account, and for specific groups. When there is a conflict between these objects, the precedence is for the most specific object:

  1. Groups - most specific and highest precedence

  2. Account - less specific and lowest precedence

In other words, if there are different DHCP settings for a group and the account, the DHCP settings for the group are used because the group is higher precedence than the account. However, you can't configure DHCP options for sites, so they are not relevant to this hierarchy.

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5 comments

  • Comment author
    praveen.nallatt

    Hello Team,

    I see the DHCP lease time updated as 72 days, is this 72 days or 72 hours ?

    Regards,

    Praveen

  • Comment author
    Dermot - Community Manager Only 42 of these badges will be awarded.  They are reserved for people who have played a key role in helping build the Cato Community through their contributions! Community Pioneer The chief of community conversations. Community manager

    Hello Praveen!

    The default DHCP lease time is 3 days (72 hours).  I'll ask the documentation team to clean this up!  Thank you for highlighting this!

    By the way, the Cato Online Community is now open and can be accessed via this link. This is a great place for asking questions, obtaining tips from Cato's employees and customers and making suggestions about Cato's services. 

    Kind Regards,

    Dermot Doran (Cato Networks Community Manager)

  • Comment author
    Uwe Thies

    This article is actually not 100% correct, I suggest correction.

    In "Working with Hierarchy for DHCP Options" it is stated that "Groups - most specific and highest precedence" but in case of DNS servers, the configured SITE DNS servers take precedence over Group settings, which may cause unexpected DNS servers to be configured with DHCP. In my case I got the native LAN1 IP address of my socket (as configured for SITE DNS) configured for a Guest WIFI instead of public DNS resolvers configured in Groups settings.

  • Comment author
    Dermot - Community Manager Only 42 of these badges will be awarded.  They are reserved for people who have played a key role in helping build the Cato Community through their contributions! Community Pioneer The chief of community conversations. Community manager

    Thank you for reporting this, Uwe.

    We will investigate and correct the KB article if required.  Progress on this investigation will be reported on via the Cato Community in the post: Configuring DHCP Settings - Is the statement about Group settings having highest precedence correct?

  • Comment author
    Yaakov Simon

    Updated the article to make it clear that the hierarchy here only refers to DHCP options, and not to other settings.

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