132
C
HAPTER
16: IP P
ERFORMANCE
C
ONFIGURATION
Configuring TCP
Attributes
Configuring to Send
Special IP Packets to
CPU
Usually the switch sends TTL timeout packets and unreachable packets to the CPU
in the process of forwarding IP packets. The CPU processes these special packets
after receiving them. Incorrect configuration and malicious attack will cause heavy
CPU load. You can perform the following configuration to configure not to send
corresponding packets to the CPU in order to ensure normal running.
Enabling Forwarding
of Directed Broadcasts
to a Directly
Connected Network
Broadcast packets include full-net broadcast packets and directed broadcast
packets. The destination IP address of a full-net broadcast packet is all 1s
(255.255.255.255). A directed broadcast packet is a packet whose destination IP
address is the network broadcast address of a subnet, but the source IP address is
not in the subnet. When a switch forwards a directed broadcast packet, it cannot
tell whether the packet is a broadcast packet if the switch is not connected with
the subnet.
If a directed broadcast packet reaches the destination network after being
forwarded by the switch, the switch will receive the broadcast packet, for the
switch also belongs to the subnet. Since the VLAN of the switch isolates the
broadcast domain, the switch will stop forwarding the packet to the network.
Using the commands, you can choose to forward the directed broadcast packet to
the directly connected network.
Table 77
Configure TCP attributes
Operation Command
Description
Enter system view
system-view
-
Configure timeout time for the
synwait timer in TCP
tcp timer syn-timeout
time-value
Required
The default value is
75 seconds
Configure timeout time for the
finwait timer in TCP
tcp timer fin-timeout
time-value
Required
The default value is
675 seconds
Configure the socket receiving
and sending buffer size of TCP
tcp window
window-size
Required
By default, the size
of the socket
receiving and
sending buffers is 8
KB
Table 78
Configure to send special IP packets to CPU
Operation Command
Description
Enter system view
system-view
-
Configure to send TTL
timeout packets and
unreachable packets to CPU
ip
{
ttl-expires
|
unreachables
} Required
By default,
unreachable packets
are not sent to the
CPU, while TTL timeout
packets are sent to the
CPU
Summary of Contents for Switch 7757
Page 32: ...32 CHAPTER 1 CLI OVERVIEW...
Page 70: ...70 CHAPTER 5 LOGGING IN USING MODEM...
Page 76: ...76 CHAPTER 7 LOGGING IN THROUGH NMS...
Page 86: ...86 CHAPTER 9 CONFIGURATION FILE MANAGEMENT...
Page 120: ...120 CHAPTER 13 ISOLATE USER VLAN CONFIGURATION...
Page 126: ...126 CHAPTER 14 SUPER VLAN...
Page 136: ...136 CHAPTER 16 IP PERFORMANCE CONFIGURATION...
Page 152: ...152 CHAPTER 17 IPX CONFIGURATION...
Page 164: ...164 CHAPTER 19 QINQ CONFIGURATION...
Page 172: ...172 CHAPTER 21 SHARED VLAN CONFIGURATION...
Page 182: ...182 CHAPTER 22 PORT BASIC CONFIGURATION...
Page 198: ...198 CHAPTER 24 PORT ISOLATION CONFIGURATION...
Page 208: ...208 CHAPTER 25 PORT SECURITY CONFIGURATION...
Page 224: ...224 CHAPTER 27 DLDP CONFIGURATION...
Page 232: ...232 CHAPTER 28 MAC ADDRESS TABLE MANAGEMENT...
Page 240: ...240 CHAPTER 29 CENTRALIZED MAC ADDRESS AUTHENTICATION CONFIGURATION...
Page 280: ...280 CHAPTER 30 MSTP CONFIGURATION...
Page 348: ...348 CHAPTER 35 IS IS CONFIGURATION...
Page 408: ...408 CHAPTER 39 802 1X CONFIGURATION...
Page 412: ...412 CHAPTER 40 HABP CONFIGURATION...
Page 422: ...422 CHAPTER 41 MULTICAST OVERVIEW...
Page 426: ...426 CHAPTER 42 GMRP CONFIGURATION...
Page 480: ...480 CHAPTER 47 PIM CONFIGURATION...
Page 506: ...506 CHAPTER 48 MSDP CONFIGURATION...
Page 552: ...552 CHAPTER 51 TRAFFIC ACCOUNTING CONFIGURATION...
Page 570: ...570 CHAPTER 53 HA CONFIGURATION...
Page 582: ...582 CHAPTER 54 ARP CONFIGURATION SwitchA arp protective down recover interval 200...
Page 622: ...622 CHAPTER 58 DHCP RELAY AGENT CONFIGURATION...
Page 684: ...684 CHAPTER 61 QOS CONFIGURATION...
Page 718: ...718 CHAPTER 63 CLUSTER...
Page 738: ...738 CHAPTER 67 UDP HELPER CONFIGURATION...
Page 752: ...752 CHAPTER 69 RMON CONFIGURATION...
Page 772: ...772 CHAPTER 70 NTP CONFIGURATION...
Page 796: ...796 CHAPTER 72 FILE SYSTEM MANAGEMENT...
Page 802: ...802 CHAPTER 73 BIMS CONFIGURATION...
Page 814: ...814 CHAPTER 74 FTP AND TFTP CONFIGURATION...
Page 830: ...830 CHAPTER 75 INFORMATION CENTER...
Page 836: ...836 CHAPTER 76 DNS CONFIGURATION...
Page 852: ...852 CHAPTER 77 BOOTROM AND HOST SOFTWARE LOADING...
Page 858: ...858 CHAPTER 78 BASIC SYSTEM CONFIGURATION DEBUGGING...