This section describes the resource requirements of the Network component. The actual requirements depend on the features used in the application. Therefore, the numbers provided here are guidelines only and the actual numbers may differ.

Stack Requirements

The Network Core receives events sent from the interrupt service routine (ISR) of the Ethernet (or Serial) Driver. The stack requirements for the ISR are typically less than 512 Bytes. The total stack space required for ISR depends on the interrupt nesting and therefore on the priority settings of these ISR. The stack requirements for ISR is configured in the startup_device.s file located under the Device component class. If the stack settings are not available there, the stack settings must be configured in the linker script file.

Option (under section Stack Configuration)	Increase Value by
Stack Size (in Bytes)	+ 512 for Ethernet (or Serial) Driver

Note: When using a CMSIS-RTOS, the Stack Size in the startup_*device*.s file configures only the stack space that is used by exception and interrupt service routines of the drivers. The stack size requirements depend on the maximum nesting of exception and ISR execution and therefore on the priority settings of the various interrupt and exception sources.

User code that calls API functions of the Network Component should have a minimum of 512 Bytes of stack space available. Since API functions are frequently called from threads, the thread stack size should be at least 512 Bytes (see below).

Heap Requirements

The mbed TLS component requires 90 kB of heap memory. The heap requirements are configured in the startup_device.s file, which is located under the Device component class. If the heap settings are not available in the startup file, the heap settings must be configured in the linker script file.

Option (under section Stack Configuration)	Increase Value to at least
Heap Size (in Bytes)	0x16000

CMSIS-RTOS Requirements

Currently, the Network component works in two different RTOS configurations:

CMSIS-RTOS2 RTX5: This mode uses Keil RTX5 natively. In the Manage Run-Time Environment window, the component CMSIS:RTOS2 (API):Keil RTX5 must be selected. The RTOS resources are static, configured by the system. There is no need for additional user configuration. This is the suggested option for new development.
CMSIS-RTOS2 with a generic RTOS: this mode uses a generic RTOS (such as FreeRTOS). The RTOS resources (thread, mutex and semaphore control blocks and thread stacks) are dynamically allocated. The user needs to provide memory pools big enough for the allocations in RTOS configuration.

The Network component uses threads. The Network Core thread is always started. Each Network interface starts its own thread when the interface is enabled. Thread execution starts with netInitialize.

The following table lists the components, the default thread name and priority, the default stack size and the configuration file with OS Resource Settings for stack size adjustments.

Component	Thread Name	Default Priority	Default Stack Size	Configuration File
Network:Core	netCore_Thread	`osPriorityNormal`	2048 Bytes	`Net_Config.h`
Network:Interface:ETH	netETH0_Thread	`osPriorityAboveNormal`	512 Bytes	`Net_Config_ETH_0.h`
Network:Interface:WiFi	netWiFi0_Thread	`osPriorityAboveNormal`	512 Bytes	`Net_Config_WiFi_0.h`
Network:Interface:PPP	netPPP_Thread	`osPriorityAboveNormal`	512 Bytes	`Net_Config_PPP.h`
Network:Interface:SLIP	netSLIP_Thread	`osPriorityAboveNormal`	512 Bytes	`Net_Config_SLIP.h`
Security:mbed TLS	netTLS_Thread	`osPriorityNormal`	4096 Bytes	`TLS_mbed.c`

For the Network Component, the number of threads and stack size requirements are calculated as follows:

Number of Threads: sum up the number of used Components.
Total stack size: sum up the Default Stack Sizes of the related threads.

Timers

The Network component requires timers which need to be enabled in RTOS.

Signals

When using BSD sockets in blocking mode, the signal (1<<15) in that thread is reserved for the Network library. A user thread, when blocked on BSD sockets, is waiting for the signal 0x8000 to resume. The event, which has caused the thread to resume, is provided internally in the library. Therefore, signal 0x8000 must not be used by the user application in that thread.

Memory Requirements

The following table shows the memory requirements for read-only (Flash) and read-write (RAM) memory. These numbers may be used to estimate the total size requirements of the application, but the actual numbers depend on compiler optimizations and target processor and may be therefore slightly different.

Network (IPv4/IPv6)

Component	RO Memory [Bytes]	RW Memory (Data) [Bytes]
Network:Core (with IPv4/IPv6)	7.5 k	0.4 k + Memory Pool size (configured in Net_Config.h)
Network:Interface:ETH (with ARP, NDP, IGMP, DHCP, NBNS)	15.7 k	0.9 k
Network:Interface:WiFi (with ARP, NDP, IGMP, DHCP, NBNS)	15.6 k	0.9 k
Network:Interface:PPP (with CHAP/PAP and Modem)	8.3 k	0.6 k
Network:Interface:SLIP (with Modem)	2.8 k	0.5 k
Network:Socket:UDP	1.5 k	0.1 k
Network:Socket:TCP	6.1 k	0.6 k
Network:Socket:BSD (without UDP/TCP)	6.5 k	0.3 k
Network:Service:DNS Client	1.8 k	0.3 k
Network:Service:FTP Client	2.5 k	< 0.1 k
Network:Service:FTP Server	5.4 k	0.2 k
Network:Service:SMTP Client	5.6 k	0.2 k
Network:Service:SNMP Agent	2.7 k	< 0.1 k
Network:Service:SNTP Client	0.8 k	< 0.1 k
Network:Service:TFTP Client	1.4 k	< 0.1 k
Network:Service:TFTP Server	2.3 k	0.1 k
Network:Service:Telnet Server	3.2 k	0.4 k
Network:Service:Web Server (HTTP Server)	7.6 k	0.5 k
Ethernet MAC Driver	1 .. 4 k	0 .. 10 k
Ethernet PHY Driver	< 1 k	< 0.1 k

Network (IPv4)

Component	RO Memory [Bytes]	RW Memory (Data) [Bytes]
Network:Core (with IPv4)	4.6 k	0.4 k + Memory Pool size (configured in Net_Config.h)
Network:Interface:ETH (with ARP,IGMP, DHCP, NBNS)	9.3 k	0.3 k
Network:Interface:WiFi (with ARP, IGMP, DHCP, NBNS)	9.3 k	0.3 k
Network:Interface:PPP (with CHAP/PAP and Modem)	8.3 k	0.6 k
Network:Interface:SLIP (with Modem)	2.8 k	0.5 k
Network:Socket:UDP	1.4 k	< 0.1 k
Network:Socket:TCP	5.7 k	0.5 k
Network:Socket:BSD (without UDP/TCP)	5.9 k	0.2 k
Network:Service:DNS Client	1.6 k	0.2 k
Network:Service:FTP Client	2.5 k	< 0.1 k
Network:Service:FTP Server	5.4 k	0.2 k
Network:Service:SMTP Client	5.6 k	0.2 k
Network:Service:SNMP Agent	2.7 k	< 0.1 k
Network:Service:SNTP Client	0.8 k	< 0.1 k
Network:Service:TFTP Client	1.4 k	< 0.1 k
Network:Service:TFTP Server	2.3 k	0.1 k
Network:Service:Telnet Server	3.2 k	0.4 k
Network:Service:Web Server (HTTP Server)	7.6 k	0.5 k
Ethernet MAC Driver	1 .. 4 k	0 .. 10 k
Ethernet PHY Driver	< 1 k	< 0.1 k