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The value of the kernel variable ip_subnetsarelocal is initialized from this
constant. If 1 (default), a destination IP address with the same network ID as the sending file:///D|/Documents%20and%20Settings/bigini/Docu...homenet2run/tcpip/tcp-ip-illustrated/append_e.htm (3 of 16) [12/09/2001 14.48.06] Appendix E: Configurable Options host but a different subnet ID is considered local. If 0, only destination IP addresses on
an attached subnet are considered local. This is summarized in Figure E.1. When sending
to local destinations, TCP chooses the MSS based on the MTU of the outgoing interface.
When sending to nonlocal destinations, TCP uses the variable tcp_default_mss.
The value of this constant initializes the kernel variable ip_sendredirects. If 1
(default), the host will send ICMP redirects when forwarding IP datagrams. If 0, ICMP
redirects are not sent.
The value of this constant initializes the kernel variable ip_dirbroadcast. If 1
(default), received datagrams whose destination .address is the directed broadcast address
of an attached interface are forwarded as a link-layer broadcast. If 0, these datagrams are
The file /usr/kvm/sys/netinet/in_proto.c defines the following variables
that can be changed. Once these variables are changed, a new kernel must be made and
rebooted. tcp_default_mss The default TCP MSS for nonlocal destinations. Default value
is 512. tcp_sendspace The default size of the TCP send buffer. Default value is 4096. tcp_recvspace The default size of the TCP receive buffer. This affects the
window size that is offered. Default value is 4096. tcp_keeplen A keepalive probe to a 4.2BSD host must contain a single byte
of data to get a response. Set the variable to 1 for compatibility
with these older implementations. Default value is 1. tcp_ttl The default value for the TTL field for TCP segments. Default
value is 60. tcp_nodelack If nonzero, ACKs are not delayed. Default value is 0. tcp_keepidle Number...
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.
- Spring '12