2-2 
Table 2-2 Configure TCP attributes 
Operation  Command  Remarks 
Enter system view 
system-view 
— 
Configure TCP synwait timer’s 
timeout value 
tcp timer syn-timeout 
time-value 
Optional 
By default, the timeout value is 
75 seconds. 
Configure TCP finwait timer’s 
timeout value 
tcp timer fin-timeout 
time-value 
Optional 
By default, the timeout value is 
675 seconds. 
Configure the size of TCP 
receive/send buffer 
tcp window window-size 
Optional 
By default, the buffer is 8 
kilobytes. 
 
Disabling ICMP to Send Error Packets 
Sending error packets is a major function of ICMP protocol. In case of network abnormalities, ICMP 
packets are usually sent by the network or transport layer protocols to notify corresponding devices so 
as to facilitate control and management. 
By default, Switch 4210 Family support sending ICMP redirect and destination unreachable packets. 
Although sending ICMP error packets facilitate control and management, it still has the following 
disadvantages: 
z  Sending a lot of ICMP packets will increase network traffic. 
z  If receiving a lot of malicious packets that cause it to send ICMP error packets, the device’s 
performance will be reduced. 
z  As the ICMP redirection function increases the routing table size of a host, the host’s performance 
will be reduced if its routing table becomes very large. 
z  If a host sends malicious ICMP destination unreachable packets, end users may be affected. 
You can disable the device from sending such ICMP error packets for reducing network traffic and 
preventing malicious attacks. 
Table 2-3 Disable sending ICMP error packets 
Operation  Command  Remarks 
Enter system view 
system-view 
— 
Disable sending ICMP redirects 
undo icmp redirect send 
Required 
Enabled by default 
Disable sending ICMP 
destination unreachable 
packets 
undo icmp unreach send 
Required 
Enabled by default 
 
Displaying and Maintaining IP Performance Configuration 
After the above configurations, you can execute the display command in any view to display the 
running status to verify your IP performance configuration.