Ping大包

Ping大包
华为交换机
可以通过Ping命令的-s packetsize参数指定Ping报文的大小，参数的取值范围是20～9600，单位是字节，缺省是56字节。如设置Ping大包为4096字节，ping -s 4096 192.168.1.1。
<华为交换机>ping ?
  -8021p         Specify the 8021p value for ECHO Request packets to be sent,
                 and the default value is 0
  -a             Select source IP address, the default is the IP address of the
                 output interface
  -c             Specify the number of echo requests to be sent, the default is
                 5
  -d             Specify the SO_DEBUG option on the socket being used
  -dscp          Specify the DSCP value for ECHO Request packets to be sent,
                 and the default value is 0
  -f             Set Don't Fragment flag in packet (IPv4-only)
  -h             Specify TTL value for echo requests to be sent, the default is
                 255
  -i             Select the interface sending packets
  -m             Time in milliseconds to wait for sending next packet, the
                 default is 500ms
  -n             Numeric output only. No attempt will be made to lookup host
                 addresses for symbolic names
  -name          Display the host name of the destination address
  -nexthop       Nexthop information
  -p             No more than 8 "pad" hexadecimal characters to fill out the
                 sent packet. For example -p f2 will fill the sent packet with
                 f and 2 repeatedly
  -q             Quiet output. Nothing is displayed except the summary lines at
                 startup time and when finished
  -r             Record route. Includes the RECORD_ROUTE option in the
                 ECHO_REQUEST packet and displays the route
  -range         Specify the length range of data to be sent (in bytes), the
                 default is <56-9600>, and the step is 1
  -ri            Display the source interface of echo response packet
  -s             Specify the number of data bytes to be sent, the default is
                 56bytes
  -si            Set the specified interface as the source interface of ping
                 packet
  -system-time   Display the sending time of echo request packets
  -t             Timeout in milliseconds to wait for each reply, the default is
                 2000ms
  -tos           Specify TOS value for echo requests to be sent, the default is
                 0
  -v             Verbose output. ICMP packets other than ECHO_RESPONSE those
                 are received are listed
  STRING<1-255>  IP address or hostname of a remote system
  ignore-mtu     Send packets without checking the interface MTU
  ip             IP Protocol
  ipv6           IPv6 protocol
  mac            MAC address
  mac-8021ag     Send MAC ping message
<华为交换机>    

有时候ping大包掉包是正常的：
（1）PC上ping 30000的大包，由于PC默认的MTU是1500，因此报文会被分片，由于报文比较大，报文会被分成几十片，这样短时间里大量报文上送，超了（华为某款交换机）设备接口板的CPCAR值导致丢包，正常的。

（2）大包测试转发接口，ping交换机设备本身，要上送cpu处理，分片报文不支持快回，导致丢包，正常的。

（3）问题描述：新增S5700进行设备入网，入网后进行链路测试，从S5700上Ping对端设备端口地址，Ping大包的时候会出现丢包的现象。
解决方案
1、查看端口光功率，数值正常；更换光模块后，问题依旧；
2、更改端口协商模式，问题依旧；
3、协调传输维护人员配合排查，未发现问题；
4、Ping测试过程中发现丢包频率很有规律，且测试过程中设备出现告警信息：
May 25 2011 00:54:31 FJ_ZZ_FZ_VPDN_9306 %%01QOSE/4/CPCAR_DROP_MPU(l): Some packets are dropped by cpcar on the MPU. (Protocol=icmp, Drop-Count=023)0/0，由此可以断定丢包问题是由于设备的自我保护机制所引起：如果同一时间内收到大量协议报文并上送主控板进行处理，会占用大量CPU资源，严重时会导致设备正常业务不通。S9300能够对各种上送主控板的协议报文分别做CAR，限制这些报文上送主控板CPU的速率。系统通过CPCAR限制报文上送主控板CPU的速率，可通过命令修改cpcar解决。配置命令：
系统视图配置某个报文类型的cpcar命令： cpcar packet-type [slot slot-number]
CPCAR视图配置针对该报文类型的CAR值：car cir cir-value [  cbs cbs-value ]。另外，上网业务若通过S9306转发，是直接通过硬件转发，不需要上送CPU处理，所以该自我保护机制对于S9306上业务数据转发是没有影响的。

<华为交换机>ping -s 1000 8.8.8.8
  PING 8.8.8.8: 1000  data bytes, press CTRL_C to break
    Reply from 8.8.8.8: bytes=68 Sequence=1 ttl=110 time=47 ms
    Reply from 8.8.8.8: bytes=68 Sequence=2 ttl=110 time=45 ms
    Reply from 8.8.8.8: bytes=68 Sequence=3 ttl=110 time=54 ms
    Reply from 8.8.8.8: bytes=68 Sequence=4 ttl=110 time=46 ms
    Reply from 8.8.8.8: bytes=68 Sequence=5 ttl=110 time=45 ms
  --- 8.8.8.8 ping statistics ---
    5 packet(s) transmitted
    5 packet(s) received
    0.00% packet loss
    round-trip min/avg/max = 45/47/54 ms
<华为交换机>

windows系统
ping -l 指定ping包的大小，默认32字节。

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