Table of Contents

Chapter 1 IP Performance Configuration. 1-1

1.1 MTU Size Configuration. 1-1

1.2 TCP Packet Fragmentation Configuration. 1-1

1.3 TCP Property Configuration. 1-1

1.4 Displaying and Debugging IP Performance. 1-2

1.5 Troubleshooting IP Performance Configuration. 1-3

Chapter 2 IP Application Configuration. 2-1

2.1 ARP Configuration. 2-1

2.1.1 Introduction to ARP. 2-1

2.1.2 Configuring Static ARP. 2-1

2.1.3 Displaying and Debugging ARP. 2-2

Chapter 1  IP Performance Configuration

1.1  MTU Size Configuration

The maximum transmission unit (MTU) decides whether the IP packets on an interface should be fragmented.

Perform the following configuration in interface view.

Table 1-1 Configure an MTU size

By default, the MTU size is 1500 bytes.

1.2  TCP Packet Fragmentation Configuration

The MTU decides whether the TCP packets on an interface should be fragmented.

Perform the following configuration in interface view.

Table 1-2 Configure TCP packet fragmentation

By default, TCP packets are not fragmented.

1.3  TCP Property Configuration

You can configure the following TCP properties:

l           synwait timer: When sending syn packets, the synwait timer is started. If no response packet is received before synwait timer times out, the TCP connection will be terminated. The timeout time of this timer ranges from 2 to 600 seconds, and defaults to 75 seconds.

l           finwait timer: When the TCP connection status changes from FIN_WAIT_1 to FIN_WAIT_2, the finwait timer is started. If no FIN packet is received before finwait timer times out, the TCP connection will be terminated. The timeout time of this timer ranges from 76 to 3600 seconds, and defaults to 675 seconds.

l           The receive/send buffer size of connection-oriented socket: The buffer size ranges from 1 to 32 KB and defaults to 8 KB.

Perform the following configuration in system view.

Table 1-3 Configure TCP properties

By default, the TCP finwait timer is set to 675 seconds, the TCP synwait timer is set to 75 seconds, and the receive/send buffer size of a connection-oriented socket is 8 KB.

1.4  Displaying and Debugging IP Performance

Use the display command to display and verify IP performance configurations.

Use the reset command to clear the statistics of the running status.

Use the debugging command in user view to debug the IP performance.

Table 1-4 Display and debug IP performance

1.5  Troubleshooting IP Performance Configuration

Symptom: TCP and UDP are established on IP protocol to provide the transmission of datagram. The problem is that TCP and UDP cannot operate properly.

Solution: You can enable the corresponding debugging to view the debugging information.

l           Use the debugging udp packet command to enable UDP debugging to trace UDP packets. When an XE IP PBX sends or receives an UDP packet, the content format of the datagram can be displayed in real time. You can locate the problem by the content of the datagram.

Following is the format of an UDP datagram:

*0.377770-SOCKET-8-UDP:

1043494431: Output: task = ROUT(6), socketid = 3,

src = 1.1.1.1:520, dst = 255.255.255.255:520, datalen = 24

l           Use the debugging tcp packet command to enable the TCP debugging to trace TCP packets. Two types of TCP datagrams can be debugged and traced. One of them is to debug and trace the receiving/sending of all TCP datagrams of the TCP connection. The operations are as follows:

[XE] info-center enable

[XE] quit

< XE > debugging tcp packet

After running the above commands, you can check the received/sent TCP datagrams in real time. The detailed packet formats are as follows:

*0.100070-SOCKET-8-TCP PACKET:

1043204051:  Input: Co0(5) socketId = 2, state = SYN_SENT,

src = 127.0.0.1:1025, dst = 2.2.2.2:23,

seq = 11084380, ack = 0, optlen = 4, flag = SYN ,

window = 8192

The other is to debug and trace the datagrams where the SYN, FIN or RST flag is set. The operations are as follows:

[XE] info-center enable

[XE] quit

< XE > debugging tcp event

After running the above commands, you can check the received/sent TCP datagrams in real time. Their formats are similar to those mentioned above.

Chapter 2  IP Application Configuration

2.1  ARP Configuration

2.1.1  Introduction to ARP

Address resolution protocol (ARP) is mainly used for resolution from IP address to an Ethernet MAC address. Normally, ARP runs dynamically and automatically resolves an IP address to an Ethernet MAC address, that is, no operation from the administrator is needed.

In Comware implementation, the system creates or updates ARP table entries when the received ARP packet meets any of the following criteria:

l           The source IP address of the ARP packet is in the same network segment as the IP address of the inbound interface, and it is not a broadcast address; the destination IP address is the IP address of this interface.

l           The source IP address of the ARP packet is in the same segment as the IP address of the inbound interface, and it is not a broadcast address; the destination IP address is the VRRP virtual IP address of this interface.

l           The destination IP address of the ARP packet belongs to the configured NAT address pool on the inbound interface.

If the source IP address of the received ARP packet already has a corresponding dynamic entry in the ARP table of the inbound interface, the ARP table entry will be updated. If the source IP address of the received ARP packet already has a corresponding static entry in the ARP table of the inbound interface, the ARP table entry will not be updated.  

To enable the proxy ARP function or to filter some illegal IP addresses (such as binding these illegal addresses to a nonexistent MAC address), you need to configure a corresponding entry in the static ARP table.

2.1.2  Configuring Static ARP

The static ARP configuration includes manually adding and deleting static ARP mapping entry.

Perform the following configuration in system view.

Table 2-1 Manually add/delete static ARP mapping entry

Static ARP mapping entries are always valid as long as the XE IP PBX operates normally, whereas dynamic ARP mapping entries are valid for only 20 minutes.

By default, dynamic ARP protocol obtains the address mapping.

The system can have up to 2,048 static ARP mapping entries.

2.1.3  Displaying and Debugging ARP

After the above configuration, execute the display command in any view to display and verify ARP configurations.

Use the reset command to clear the ARP entry.

Use the debugging command in user view to debug ARP.

Table 2-2 Display and debug ARP