> This page is for version 11 (default). > For other versions, use one of these documentation indexes: > - 11 (default): https://docs.nvidia.com/base-command-manager/product-manuals/11/llms.txt > - 10: https://docs.nvidia.com/base-command-manager/product-manuals/10/llms.txt > For clean Markdown of any page, append .md to the page URL. > For a complete documentation index, see https://docs.nvidia.com/base-command-manager/product-manuals/llms.txt. > For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.nvidia.com/base-command-manager/product-manuals/_mcp/server. # Changing The Network Parameters Of The Head Node ## 6.1 Introduction After a cluster physically arrives at its site, the administrator often has to change the network settings to suit the site. Details on this are given in [section 3.2.1 of the *Administrator Manual*](/admin/configuring#321-configuring-networks). However, it relies on understanding the material leading up to that section. This chapter is therefore a quickstart document—conveniently a mere 3 pages—explaining how to change basic IPv4 network settings while assuming no prior knowledge of NVIDIA Base Command Manager and its network configuration interface. ## 6.2 Method A cluster consists of a head node, say `basecm11` and one or more regular nodes. The head node of the cluster is assumed to face the internal network (the network of regular nodes) on one interface, say `eth0`. The external network leading to the internet is then on another interface, say `eth1`. This is referred to as a *type 1* configuration in this manual (section [3.3.9](/installation/installing#339-network-topology)). Typically, an administrator gives the head node a static external IP address before actually connecting it up to the external network. This requires logging into the physical head node with the vendor-supplied root password. The original network parameters of the head node can then be viewed and set. For example for `eth1`: ```bash # cmsh -c "device interfaces basecm11; get eth1 dhcp" yes ``` Here, `yes` means the interface accepts DHCP server-supplied values. Disabling DHCP acceptance allows a static IP address, for example `192.168.1.176`, to be set: ```bash # cmsh -c "device interfaces basecm11; set eth1 dhcp no" # cmsh -c "device interfaces basecm11; set eth1 ip 192.168.1.176; commit" # cmsh -c "device interfaces basecm11; get eth1 ip" 192.168.1.176 ``` Other external network parameters can be viewed and set in a similar way, as shown in table [6.1](#externalnetworkparametersandhowtochangethemontheheadnode). A reboot implements the networking changes. *Table 6.1: External Network Parameters And How To Change Them On The Head Node*
**Network Parameter** **Description** **Operation** **Command Used**
IP \* IP address of head node on eth1 interface view `cmsh -c "device interfaces basecm11; get eth1 ip"`
set `cmsh -c "device interfaces basecm11; set eth1 ip ` *`address`* `; commit"`
baseaddress \* base IP address (network address) of network view `cmsh -c "network get externalnet baseaddress"`
set `cmsh -c "network; set externalnet baseaddress ` *`address`* `; commit"`
broadcastaddress \* broadcast IP address of network view `cmsh -c "network get externalnet broadcastaddress"`
set `cmsh -c "network; set externalnet broadcastaddress ` *`address`* `; commit"`
netmaskbits netmask in CIDR notation (number after “/”, or prefix length) view `cmsh -c "network get externalnet netmaskbits"`
set `cmsh -c "network; set externalnet netmaskbits ` *`bitsize`* `; commit"`
gateway \* gateway IP address (default route) view `cmsh -c "network get externalnet gateway"`
set `cmsh -c "network; set externalnet gateway ` *`address`* `; commit"`
nameservers *, \** nameserver IP addresses view `cmsh -c "partition get base nameservers"`
set `cmsh -c "partition; set base nameservers ` *`address`* `; commit"`
searchdomains \** name of search domains view `cmsh -c "partition get base searchdomains"`
set `cmsh -c "partition; set base searchdomains ` *`hostname`* `; commit"`
timeservers \** name of timeservers view `cmsh -c "partition get base timeservers"`
set `cmsh -c "partition; set base timeservers ` *`address`* `; commit"`
\* If *address* is set to 0.0.0.0 then the value offered by the DHCP server on the external network is accepted\ \*\* Space-separated multiple values are also accepted for these parameters when setting the value for *address* or *hostname*. ## 6.3 Terminology A reminder about the less well-known terminology in the table: * `netmaskbits` is the netmask size, or prefix-length, in bits. In IPv4’s 32-bit addressing, this can be up to 31 bits, so it is a number between 1 and 31. For example: networks with 256 (2⁸) addresses (i.e. with host addresses specified with the last 8 bits) have a netmask size of 24 bits. They are written in CIDR notation with a trailing “`/24`”, and are commonly spoken of as “slash 24” networks. * `baseaddress` is the IP address of the network the head node is on, rather than the IP address of the head node itself. The `baseaddress` is specified by taking `netmaskbits` number of bits from the IP address of the head node. Examples: * A network with 256 (2⁸) host addresses: This implies the first 24 bits of the head node’s IP address are the network address, and the remaining 8 bits are zeroed. This is specified by using “0” as the last value in the dotted-quad notation (i.e. zeroing the last 8 bits). For example: 192.168.3.0 * A network with 128 (2⁷) host addresses: Here `netmaskbits` is 25 bits in size, and only the last 7 bits are zeroed. In dotted-quad notation this implies “128” as the last quad value (i.e. zeroing the last 7 bits). For example: 192.168.3.128. When in doubt, or if the preceding terminology is not understood, then the values to use can be calculated using the head node’s `sipcalc` utility. To use it, the IP address in CIDR format for the head node must be known. When run using a CIDR address value of 192.168.3.130/25, the output is (some output removed for clarity): ```bash # sipcalc 192.168.3.130/25 Host address - 192.168.3.130 Network address - 192.168.3.128 Network mask - 255.255.255.128 Network mask (bits) - 25 Broadcast address - 192.168.3.255 Addresses in network - 128 Network range - 192.168.3.128 - 192.168.3.255 ``` Running it with the `-b` (binary) option may aid comprehension: ```bash # sipcalc -b 192.168.3.130/25 Host address - 11000000.10101000.00000011.10000010 Network address - 11000000.10101000.00000011.10000000 Network mask - 11111111.11111111.11111111.10000000 Broadcast address - 11000000.10101000.00000011.11111111 Network range - 11000000.10101000.00000011.10000000 - 11000000.10101000.00000011.11111111 ```