H3C Technologies H3C S5560 Series Switches - Manual (Page 144)

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Step Command Remarks
1. Enter system view. system-view N/A
2. Enable SYN Cookie. tcp syn-cookie enable The default setting is disabled.
Configuring the TCP buffer size
Step Command Remarks
1. Enter system view. system-view N/A
2. Configure the size of TCP receive/send
buffer.
tcp window window-size The default buffer size is 64 KB.
Configuring TCP timers
You can configure the following TCP timers:
• SYN wait timer—TCP starts the SYN wait timer after sending a SYN packet. If no response packet
is received within the SYN wait timer interval, TCP fails to establish the connection.
• FIN wait timer—TCP starts the FIN wait timer when the state changes to FIN_WAIT_2. If no FIN
packet is received within the timer interval, TCP terminates the connection. If a FIN packet is
received, TCP changes connection state to TIME_WAIT. If a non-FIN packet is received, TCP restarts
the timer, and tears down the connection when the timer expires.
To configure TCP timers:
Step Command Remarks
1. Enter system view. system-view N/A
2. Configure TCP
timers.
• Configure the TCP SYN wait timer:
tcp timer syn-timeout time-value
• Configure the TCP FIN wait timer:
tcp timer fin-timeout time-value
By default:
• The TCP SYN wait timer is 75
seconds.
• The TCP FIN wait timer is 675
seconds.
Enabling sending ICMP error messages
Perform this task to enable sending ICMP error messages, including redirect, time-exceeded, and
destination unreachable messages.
• ICMP redirect messages
A host that has only one default route sends all packets to the default gateway. The default
gateway sends an ICMP redirect message to inform the host of a correct next hop by following
these rules:
{
The receiving and sending interfaces are the same.
{
The selected route is not created or modified by any ICMP redirect message.