3Com Router User Manual

Configure Network Address Translation (NAT)357
Fault 2: Internal server abnormal
Troubleshooting: If an external host cannot access the internal server normally, 
check the configuration on the internal server host, or the internal server 
configuration on the router. Its possible that the internal server IP address is 
wrong, or that the firewall has inhibited the external host to access the internal 
network. Use the command 
display rule for further check. 

358CHAPTER 21: CONFIGURING IP APPLICATION 

22
CONFIGURING IP PERFORMANCE
This chapter contains information on the following topics:
■Configure IP Performance 
■Configure TCP Performance 
■Configure Fast Forwarding
■Display and Debug IP Performance
■Troubleshooting IP Performance Configuration 
Configure IP 
Performance To configure IP performance, carry out the following steps:
1Configure MTU on an Interface
Perform the following configuration in interface view.
Ta b l e 389   Configure maximum transmission unit on an interface
When the Ethernet...

360CHAPTER 22: CONFIGURING IP PERFORMANCE
Ta b l e 391   Configure router forwarding redirect packets
By default, router forwarding redirect packets is enabled. 
4Configure Router Receiving/Forwarding Source Route Packets
The following configurations should be made in system view. 
Ta b l e 392   Configure router receiving/forwarding source address route packets
By default, router receiving/forwarding source address route packets is disabled.  
Configure TCP 
Performance To configure TCP performance,...

Configure TCP Performance 361
The Synwait timers timeout ranges between 2~600 seconds, with a default value 
of 75 seconds. The Finwait timers timeout ranges between 76~3600 seconds, 
with a default value of 675 seconds. The value of window-size ranges between 
1~32Kbytes, with a default value of 4Kbytes.
Configure the size of the receiving and sending 
window for TCP Socket.tcp window size 

362CHAPTER 22: CONFIGURING IP PERFORMANCE
Configure Fast 
ForwardingMessage forwarding efficiency is a key feature evaluating router performance. 
According to regular flow, when a message arrives, the router will copy it from the 
interface memory to the main CPU. The CPU specifies the network ID from the IP 
address, consults with the routing table to get the best path to forward the 
message, and creates MAC frame suitable for output of the message. The created 
MAC frame is copied to the output queue...

Display and Debug IP Performance363
By default, fast-forwarding is enabled in the input/output directions of the 
interface.
When fast-forwarding is carried out on an interface, note that:
■You can disable fast-forwarding as necessary. For example, if load sharing is 
required, fast-forwarding must be disabled in the forwarding direction of the 
interface.
■If fast-forwarding has been configured on an interface, the interface will not 
send any ICMP redirected packets.
2Configure fast-forwarding table...

364CHAPTER 22: CONFIGURING IP PERFORMANCE
Troubleshooting IP 
Performance 
Configuration Fault 1: TCP and UDP are created upon IP protocol, and IP is able to provide 
data packet transmission. However, TCP and UDP protocols do not work 
normally
Troubleshooting: Turn on corresponding debugging switches to check the 
debugging information
■Use the debugging udp command to turn on the UDP debugging switch, and 
trace the UDP data packet. When the router sends or receives UDP data 
packets, the packet...

23
CONFIGURING IP COUNT 
This chapter contains information on the following topics:
■IP Count Introduction
■IP Count Configuration
■Display and Debug IP Count
■Typical Configuration Example
■Troubleshooting
IP Count IntroductionIP Count makes the statistics about the input and output packets, and the packets 
denied by the firewall as well. When making the statistics, the router classifies the 
bidirectional (in and out) IP packets by testing whether they match any IP Count 
lists and whether they are...

366CHAPTER 23: CONFIGURING IP COUNT
Figure 134   Networking for an IP Count application
IP Count mainly implements the following functions:
■Configure IP Count list
■Make statistics on the output and input packets
■Make statistics on the packets processed by the firewall
■Display all packet statistics
■Clear all packet statistics
IP Count 
ConfigurationBasic Configuration includes:
■Enable IP Count Service
■Enable IP Count on an interface
Advanced Configuration includes:
■Configure IP Count list...