In our datacenter application, a single DHCP server is servicing 36000+ clients. Improvements are required to the DHCPv4 retransmission behavior to align with RFC and ensure less pressure is exerted on the server: - retransmission backoff interval maximum is configurable (environment variable bootpretransmitperiodmax) - initial retransmission backoff interval is configurable (environment variable bootpretransmitperiodinit) - transaction ID is kept the same for each BOOTP/DHCPv4 request (not recreated on each retry)
For our application we'll use: - bootpretransmitperiodmax=16000 - bootpretransmitperiodinit=2000 A new configuration BOOTP_RANDOM_XID has been added to enable a randomized BOOTP/DHCPv4 transaction ID. Enhance DHCPv4 sending/parsing option 209 (PXE config file). A previous patch was accepted. A new patch fixes a possible double free() and addresses latest review comments. Changes in v6: - CMD_BOOTP should "depends on LIB_RAND || LIB_HW_RAND" Changes in v5: - add change log to individual patches - fix depends for BOOTP_RANDOM_XID: "depends on CMD_BOOTP && (LIB_RAND || LIB_HW_RAND)" Changes in v4: - rebase master and resolve conflicts - default y for BOOTP_PXE_DHCP_OPTION (feedback from review) - Add "select LIB_RAND" for "config CMD_BOOTP" (retransmission improvements require rand()) Changes in v3: - add define for option 209 and rfc5071 reference - Set RETRANSMIT_PERIOD_MAX_MS=60000 - Add randomization factor to retransmission timeout - Add depends for BOOTP_RANDOM_XID Changes in v2: - use env_get_ulong() to get environment variables Sean Edmond (3): net: Enhancements for dhcp option 209 net: bootp: BOOTP/DHCPv4 retransmission improvements net: bootp: add config option BOOTP_RANDOM_XID cmd/Kconfig | 10 ++++++- cmd/pxe.c | 2 ++ net/bootp.c | 76 +++++++++++++++++++++++++++++++++++++++++------------ net/bootp.h | 2 ++ 4 files changed, 72 insertions(+), 18 deletions(-) -- 2.42.0
