menu "LWIP" config L2_TO_L3_COPY bool "Enable copy between Layer2 and Layer3 packets" default n help If this feature is enabled, all traffic from layer2(WIFI Driver) will be copied to a new buffer before sending it to layer3(LWIP stack), freeing the layer2 buffer. Please be notified that the total layer2 receiving buffer is fixed and ESP32 currently supports 25 layer2 receiving buffer, when layer2 buffer runs out of memory, then the incoming packets will be dropped in hardware. The layer3 buffer is allocated from the heap, so the total layer3 receiving buffer depends on the available heap size, when heap runs out of memory, no copy will be sent to layer3 and packet will be dropped in layer2. Please make sure you fully understand the impact of this feature before enabling it. config LWIP_MAX_SOCKETS int "Max number of open sockets" range 1 32 default 10 help Sockets take up a certain amount of memory, and allowing fewer sockets to be open at the same time conserves memory. Specify the maximum amount of sockets here. The valid value is from 1 to 16. config LWIP_THREAD_LOCAL_STORAGE_INDEX int "Index for thread-local-storage pointer for lwip" default 0 help Specify the thread-local-storage-pointer index for lwip use. config LWIP_SO_REUSE bool "Enable SO_REUSEADDR option" default n help Enabling this option allows binding to a port which remains in TIME_WAIT. config LWIP_SO_RCVBUF bool "Enable SO_RCVBUF option" default n help Enabling this option allows checking for available data on a netconn. config LWIP_DHCP_MAX_NTP_SERVERS int "Maximum number of NTP servers" default 1 range 1 16 help Set maximum number of NTP servers used by LwIP SNTP module. First argument of sntp_setserver/sntp_setservername functions is limited to this value. config LWIP_IP_FRAG bool "Enable fragment outgoing IP packets" default n help Enabling this option allows fragmenting outgoing IP packets if their size exceeds MTU. config LWIP_IP_REASSEMBLY bool "Enable reassembly incoming fragmented IP packets" default n help Enabling this option allows reassemblying incoming fragmented IP packets. menu "TCP" config TCP_MAXRTX int "Maximum number of retransmissions of data segments" default 12 range 3 12 help Set maximum number of retransmissions of data segments. config TCP_SYNMAXRTX int "Maximum number of retransmissions of SYN segments" default 6 range 3 12 help Set maximum number of retransmissions of SYN segments. config TCP_MSS int "Maximum Segment Size (MSS)" default 1436 range 1220 1436 help Set maximum segment size for TCP transmission. Can be set lower to save RAM, the default value 1436 will give best throughput. config TCP_MSL int "Maximum segment lifetime (MSL)" default 60000 help Set maximum segment lifetime in in milliseconds. config TCP_SND_BUF_DEFAULT int "Default send buffer size" default 5744 # 4 * default MSS range 2440 65535 help Set default send buffer size for new TCP sockets. Per-socket send buffer size can be changed at runtime with lwip_setsockopt(s, TCP_SNDBUF, ...). This value must be at least 2x the MSS size, and the default is 4x the default MSS size. Setting a smaller default SNDBUF size can save some RAM, but will decrease performance. config TCP_WND_DEFAULT int "Default receive window size" default 5744 # 4 * default MSS range 2440 65535 help Set default TCP receive window size for new TCP sockets. Per-socket receive window size can be changed at runtime with lwip_setsockopt(s, TCP_WINDOW, ...). Setting a smaller default receive window size can save some RAM, but will significantly decrease performance. config TCP_RECVMBOX_SIZE int "Default TCP receive mail box size" default 6 range 6 32 help Set TCP receive mail box size. Generally bigger value means higher throughput but more memory. The recommended value is: TCP_WND_DEFAULT/TCP_MSS + 2, e.g. if TCP_WND_DEFAULT=14360, TCP_MSS=1436, then the recommended receive mail box size is (14360/1436 + 2) = 12. TCP receive mail box is a per socket mail box, when the application receives packets from TCP socket, LWIP core firstly posts the packets to TCP receive mail box and the application then fetches the packets from mail box. It means LWIP can caches maximum TCP_RECCVMBOX_SIZE packets for each TCP socket, so the maximum possible cached TCP packets for all TCP sockets is TCP_RECCVMBOX_SIZE multiples the maximum TCP socket number. In other words, the bigger TCP_RECVMBOX_SIZE means more memory. On the other hand, if the receiv mail box is too small, the mail box may be full. If the mail box is full, the LWIP drops the packets. So generally we need to make sure the TCP receive mail box is big enough to avoid packet drop between LWIP core and application. config TCP_QUEUE_OOSEQ bool "Queue incoming out-of-order segments" default y help Queue incoming out-of-order segments for later use. Disable this option to save some RAM during TCP sessions, at the expense of increased retransmissions if segments arrive out of order. choice TCP_OVERSIZE prompt "Pre-allocate transmit PBUF size" default TCP_OVERSIZE_MSS help Allows enabling "oversize" allocation of TCP transmission pbufs ahead of time, which can reduce the length of pbuf chains used for transmission. This will not make a difference to sockets where Nagle's algorithm is disabled. Default value of MSS is fine for most applications, 25% MSS may save some RAM when only transmitting small amounts of data. Disabled will have worst performance and fragmentation characteristics, but uses least RAM overall. config TCP_OVERSIZE_MSS bool "MSS" config TCP_OVERSIZE_QUARTER_MSS bool "25% MSS" config TCP_OVERSIZE_DISABLE bool "Disabled" endchoice endmenu # TCP menu "UDP" config UDP_RECVMBOX_SIZE int "Default UDP receive mail box size" default 6 range 6 32 help Set UDP receive mail box size. The recommended value is 6. UDP receive mail box is a per socket mail box, when the application receives packets from UDP socket, LWIP core firstly posts the packets to UDP receive mail box and the application then fetches the packets from mail box. It means LWIP can caches maximum UDP_RECCVMBOX_SIZE packets for each UDP socket, so the maximum possible cached UDP packets for all UDP sockets is UDP_RECCVMBOX_SIZE multiples the maximum UDP socket number. In other words, the bigger UDP_RECVMBOX_SIZE means more memory. On the other hand, if the receiv mail box is too small, the mail box may be full. If the mail box is full, the LWIP drops the packets. So generally we need to make sure the UDP receive mail box is big enough to avoid packet drop between LWIP core and application. endmenu # UDP config LWIP_DHCP_DOES_ARP_CHECK bool "Enable an ARP check on the offered address" default y help Enabling this option allows check if the offered IP address is not already in use by another host on the network. config TCPIP_TASK_STACK_SIZE int "TCP/IP Task Stack Size" default 2560 help Configure TCP/IP task stack size, used by LWIP to process multi-threaded TCP/IP operations. The default is 2560 bytes, setting this stack too small will result in stack overflow crashes. menuconfig PPP_SUPPORT bool "Enable PPP support (new/experimental)" default n help Enable PPP stack. Now only PPP over serial is possible. PPP over serial support is experimental and unsupported. config PPP_PAP_SUPPORT bool "Enable PAP support" depends on PPP_SUPPORT default n help Enable Password Authentication Protocol (PAP) support config PPP_CHAP_SUPPORT bool "Enable CHAP support" depends on PPP_SUPPORT default n help Enable Challenge Handshake Authentication Protocol (CHAP) support config PPP_MSCHAP_SUPPORT bool "Enable MSCHAP support" depends on PPP_SUPPORT default n help Enable Microsoft version of the Challenge-Handshake Authentication Protocol (MSCHAP) support config PPP_MPPE_SUPPORT bool "Enable MPPE support" depends on PPP_SUPPORT default n help Enable Microsoft Point-to-Point Encryption (MPPE) support config PPP_DEBUG_ON bool "Enable PPP debug log output" depends on PPP_SUPPORT default n help Enable PPP debug log output menu "ICMP" config LWIP_MULTICAST_PING bool "Respond to multicast pings" default n config LWIP_BROADCAST_PING bool "Respond to broadcast pings" default n endmenu # ICMP endmenu