从CLI和分段识别的ASR 5000系列ICMP数据包生成
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已更新: 2015 年 7 月 27 日
文档 ID:119210
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简介
本文描述show port命令报告的字节数和ping命令，当ping在聚合服务路由器(ASR)时5000系列平台的CLI被执行。它也展示分段的作用，当发送的数据包比在接口的已配置的最大传输单元(MTU)极大时。这是有好的背景信息，当您排除故障用户平面问题与ping甚至一般来说穿过机箱的数据包的时。并且，与ping的实验在节点是一个巨大方式确认在本文解释的概念。
问题
当您指定互联网控制消息协议(ICMP)数据包的大小时，大小是指获得包裹到数据包的原始有效负载。它不包括ICMP报头(8个字节)或IP报头(20个字节)。并且知名之士是以太网报头(14个字节=目的地MAC (6) +源MAC (6) +以太网帧类型(2))， VLAN标记(4个字节)和落后的以太网帧检查顺序(FCS， 4个字节)，以后哪些不将显示在Wireshark trace。
解决方案
当您查看从show port [npu的输出|数据链接]计数器命令，可以应用的算术在本例中显示。匹配颜色为了获取直接的了解。当允许将发送的ping，不用其他流量覆盖产生的输出，此练习在与一点的端口工作对没有流量。
有效负载大小：(也是此命令的默认)的56个字节
有效负载+ ICMP报头：64
有效负载+ ICMP报头+ IP报头：84
有效负载+ ICMP报头+ IP报头+以太网报头+ VLAN标记： 102
有效负载(56) + ICMP报头(8) + IP报头(20) +以太网报头(14) + VLAN标记(4) + FCS (4) ： 106
context Ctx
interface 21/1 broadcast
ip address 10.193.82.118 255.255.255.0
ip mtu 1500
#exit
port ethernet 21/1
no shutdown
vlan 30
no shutdown
bind interface 21/1 Ctx
#exit
#exit
[Ctx]ASR5000> show ip arp
Flags codes:
I - Incomplete, R - Reachable, M - Permanent, S - Stale,
D - Delay, P - Probe, F - Failed
Address Link Type Link Address Flags Mask Interface
10.193.82.1 ether 00:00:0C:07:AC:1E R 21/1
[Ctx]ASR5000> show ip route
"*" indicates the Best or Used route. S indicates Stale.
Destination Nexthop Protocol Prec Cost Interface
*0.0.0.0/0 10.193.82.1 static 1 0 21/1
[Ctx]ASR5000> clear port data counters 21/1
Saturday April 12 14:06:21 UTC 2014
[Ctx]ASR5000> clear port npu count 21/1
Saturday April 12 14:06:21 UTC 2014
[Ctx]ASR5000> ping 10.193.82.1 count 1 size 56
Saturday April 12 14:06:21 UTC 2014
PING 10.193.82.1 (10.193.82.1) 56(84) bytes of data.
64 bytes from 10.193.82.1: icmp_seq=1 ttl=255 time=0.957 ms
--- 10.193.82.1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.957/0.957/0.957/0.000 ms
Note that the datalink counters include the FCS bytes, while both datalink and npu
counters include the ethernet frame and vlan tags.
[Ctx]ASR5000> show port datalink count 21/1
Saturday April 12 14:06:25 UTC 2014
Counters for port 21/1:
Line Card Gigabit Ethernet Port
Rx Counter Data | Tx Counter Data
----------------------- -------------- + ----------------------- -------------
RX Unicast frames 112 | TX Unicast frames 1
RX Multicast frames 3 | TX Multicast frames 0
RX Broadcast frames 9 | TX Broadcast frames 0
RX Size 64 frames 0 | TX Size 64 frames 0
RX Size 65 .. 127 fr 14 | TX Size 65 .. 127 fr 1
RX Size 128 .. 255 fr 0 | TX Size 128 .. 255 fr 0
RX Size 256 .. 511 fr 110 | TX Size 256 .. 511 fr 0
RX Size 512 .. 1023 fr 0 | TX Size 512 .. 1023 fr 0
RX Size 1024 .. 1518 fr 0 | TX Size 1024 .. 1518 fr 0
RX Size > 1518 frames 0 | TX Size > 1518 frames 0
RX Bytes OK 43966 | TX Bytes OK 106
RX Bytes BAD 0 | TX Bytes BAD 0
RX SHORT OK 0 | TX PAUSE 0
RX SHORT CRC 0 | TX ERR 0
RX OVF 0 |
RX NORM CRC 0 |
RX LONG OK 0 |
RX LONG CRC 0 |
RX PAUSE 0 |
RX FALS CRS 0 |
RX SYM ERR 0 |
----------------------- -------------- + ----------------------- -------------
[Ctx]ASR5000> show port npu count 21/1
Saturday April 12 14:06:25 UTC 2014
Counters for port 21/1
Counter Rx Frames Rx Bytes Tx Frames Tx Bytes
-------------------- ------------- --------------- ------------- ---------------
Unicast 1 102 1 102
Multicast 3 202 0 0
Broadcast 8 512 0 0
IPv4 unicast 1 102 1 102
IPv4 non-unicast 1 66 0 0
IPv6 unicast 0 0 0 0
IPv6 non-unicast 0 0 0 0
Fragments received 0 0 n/a n/a
Packets reassembled 0 0 n/a n/a
Fragments to kernel 0 0 n/a n/a
HW error 0 0 n/a n/a
Port non-operational 0 0 0 0
SRC MAC is multicast 0 0 n/a n/a
Unknown VLAN tag 0 0 n/a n/a
Other protocols 2 136 n/a n/a
Not IPv4 0 0 n/a n/a
Bad IPv4 header 0 0 n/a n/a
IPv4 MRU exceeded 0 0 n/a n/a
TCP tiny fragment 0 0 0 0
No ACL match 0 0 0 0
Filtered by ACL 0 0 0 0
TTL expired 0 0 n/a n/a
Flow lookup twice 0 0 n/a n/a
Unknown IPv4 class 0 0 n/a n/a
Too short: IP 0 0 n/a n/a
Too short: ICMP 0 0 0 0
Too short: IGMP 0 0 0 0
Too short: TCP 0 0 0 0
Too short: UDP 0 0 0 0
Too short: IPIP 0 0 n/a n/a
Too short: GRE 0 0 n/a n/a
Too short: GRE key 0 0 n/a n/a
Don't frag discards n/a n/a 0 0
Fragment packets n/a n/a 0 0
Fragment fragments n/a n/a 0 0
IPv4VlanMap dropped 0 0 n/a n/a
IPSec NATT keep alive 0 0 n/a n/a
MPLS Flow not found 0 0 n/a n/a
MPLS unicast 0 0 0 0
Size < 17 0 0 0 0
Size 17 .. 64 8 512 0 0
Size 65 .. 127 4 304 1 102
Size 128 .. 255 0 0 0 0
Size 256 .. 511 0 0 0 0
Size 512 .. 1023 0 0 0 0
Size 1024 .. 2047 0 0 0 0
Size 2048 .. 4095 0 0 0 0
Size 4096 .. 4500 0 0 0 0
Size > 4500 0 0 0 0
IP 分段
IP数据包分段发生，当数据包的大小，包括IP报头，但是没有任何Layer2数据例如来源/目的地MAC、VLAN ID或者FSC，分成多个网段为了遵照接口的(默认1500) “ip mtu”设置。 在本例中， MTU设置为默认容量1500， 1472尝试的ICMP有效载荷大小发送大于那将被分段不会被分段(1472 + ICMP报头(8) + IP报头(20) = 1500)，但是的任何。当分段发生时，有在端口npu和数据链接计数器计数的两个信息包碎片，一个在每个适当大小的桶。使用500数据包充斥ping的完成， 1000个片段发送;500大号的和500小型的。此示例在ASR 5500运行了(与在ASR 5000)的输出示例比较，但是在两平台类似运作。
[ECS]ASR500> show ip interface
Thursday July 16 00:31:39 UTC 2015
Intf Name: 5/29-ECS
Intf Type: Broadcast
Description:
VRF: None
IP State: UP (Bound to 5/29 vlan id 31, 802.1P prior 0, ifIndex 85786626)
IP Address: 10.213.137.105 Subnet Mask: 255.255.255.0
Bcast Address: 10.213.137.255 MTU: 1500
Resoln Type: ARP ARP timeout: 60 secs
L3 monitor LC-port switchover: Disabled
Number of Secondary Addresses: 0
port ethernet 5/29
no shutdown
vlan 31
no shutdown
bind interface 5/29-ECS ECS
#exit
#exit
首先，请设立计数器的一个基准。指定NPU计数器的VLAN ID (为了确认所有ping有被添附的VLAN ID)。
[ECS]ASR5500> clear port datalink counters 5/29
Friday July 17 23:53:46 UTC 2015
[ECS]ASR5500> show port datalink counters 5/29
Friday July 17 23:53:46 UTC 2015
rCounters for port 5/29:
Line Card 10 Gigabit Ethernet Port
Rx Counter Data | Tx Counter Data
----------------------- -------------- + ----------------------- -------------
RX Bytes 406 | TX Bytes 0
RX Unicast frames 0 | TX Unicast frames 0
RX Multicast frames 4 | TX Multicast frames 0
RX Broadcast frames 1 | TX Broadcast frames 0
RX Size 64 frames 0 | TX Size 64 frames 0
RX Size 65 .. 127 fr 5 | TX Size 65 .. 127 fr 0
RX Size 128 .. 255 fr 0 | TX Size 128 .. 255 fr 0
RX Size 256 .. 511 fr 0 | TX Size 256 .. 511 fr 0
RX Size 512 .. 1023 fr 0 | TX Size 512 .. 1023 fr 0
RX Size 1024 .. 1518 fr 0 | TX Size 1024 .. 1518 fr 0
RX Size 1519 .. 1522 fr 0 | TX Size 1519 .. 1522 fr 0
----------------------- -------------- + ----------------------- -------------
[ECS]ASR5500> clear port npu counters 5/29 vlan 31
Friday July 17 23:53:47 UTC 2015
[ECS]ASR5500> show port npu counters 5/29 vlan 31
Friday July 17 23:53:47 UTC 2015
Counters for port 5/29 vlan id 31:
Counter Rx Frames Rx Bytes Tx Frames Tx Bytes
-------------------- ------------- --------------- ------------- ---------------
Unicast 0 0 0 0
Multicast 3 196 0 0
Broadcast 1 64 0 0
IPv4 unicast 0 0 0 0
IPv4 non-unicast 3 196 0 0
IPv6 unicast 0 0 0 0
IPv6 non-unicast 0 0 0 0
Fragments received 0 0 n/a n/a
Packets reassembled 0 0 n/a n/a
Fragments to kernel 0 0 n/a n/a
HW error 0 0 n/a n/a
Port non-operational 539 38520 0 0
SRC MAC is multicast 0 0 n/a n/a
Unknown VLAN tag 0 0 n/a n/a
Other protocols 2 128 n/a n/a
ping incude IP报头被派出未成碎片的大小1500字节。在数据链路层的总大小(因为离开端口)是：
1472 (有效负载) + 8 (ICMP报头) + 20 (IP报头) + 14 (MAC源/目的) + 4 (VLAN ID) + 4 (FSC) = 1522
[ECS]ASR5500> ping 10.213.137.1 size 1472 flood
Friday July 17 23:53:48 UTC 2015
PING 10.213.137.1 (10.213.137.1) 1472(1500) bytes of data.
--- 10.213.137.1 ping statistics ---
500 packets transmitted, 500 received, 0% packet loss, time 422ms
rtt min/avg/max/mdev = 0.405/0.800/0.994/0.143 ms, ipg/ewma 0.845/0.802 ms
[ECS]ASR5500> show port datalink counters 5/29
Friday July 17 23:53:54 UTC 2015
Counters for port 5/29:
Line Card 10 Gigabit Ethernet Port
Rx Counter Data | Tx Counter Data
----------------------- -------------- + ----------------------- -------------
RX Bytes 771008 | TX Bytes 765656
RX Unicast frames 536 | TX Unicast frames 524
RX Multicast frames 45 | TX Multicast frames 0
RX Broadcast frames 20 | TX Broadcast frames 0
RX Size 64 frames 0 | TX Size 64 frames 0
RX Size 65 .. 127 fr 75 | TX Size 65 .. 127 fr 0
RX Size 128 .. 255 fr 24 | TX Size 128 .. 255 fr 18
RX Size 256 .. 511 fr 2 | TX Size 256 .. 511 fr 6
RX Size 512 .. 1023 fr 0 | TX Size 512 .. 1023 fr 0
RX Size 1024 .. 1518 fr 0 | TX Size 1024 .. 1518 fr 0
RX Size 1519 .. 1522 fr 500 | TX Size 1519 .. 1522 fr 500
RX OverSize frames 0 | TX OverSize frames 0
RX UnderSize frames 0 | TX UnderSize frames 0
RX ExceedMaxSize frames 0
RX Fragment frames 0 | TX Fragment frames 0
RX Jabber frames 0 | TX Jabber frames 0
RX Control frames 0 | TX Control frames 0
RX Pause frames 0 | TX Pause frames 0
RX FCS Error frames 0 | TX FCS Error frames 0
RX Length Error frames 0 | TX Length Error frames 0
RX Code Error frames 0
RX ExMaxSize Err frames 0
----------------------- -------------- + ----------------------- -------------
[ECS]ASR5500> show port npu counters 5/29 vlan 31
Friday July 17 23:53:54 UTC 2015
Counters for port 5/29 vlan id 31:
Counter Rx Frames Rx Bytes Tx Frames Tx Bytes
-------------------- ------------- --------------- ------------- ---------------
Unicast 520 761900 520 762800
Multicast 38 2811 0 0
Broadcast 18 1408 0 0
IPv4 unicast 538 763308 520 762800
IPv4 non-unicast 30 2027 0 0
IPv6 unicast 0 0 0 0
IPv6 non-unicast 8 784 0 0
Fragments received 0 0 n/a n/a
Packets reassembled 0 0 n/a n/a
Fragments to kernel 0 0 n/a n/a
HW error 0 0 n/a n/a
Port non-operational 9482 681251 0 0
SRC MAC is multicast 0 0 n/a n/a
Unknown VLAN tag 0 0 n/a n/a
Other protocols 20 1280 n/a n/a
Not IPv4 8 784 n/a n/a
...
Size 0 .. 63 0 0 0 0
Size 64 .. 127 70 5193 0 0
Size 128 .. 255 24 3408 18 2580
Size 256 .. 511 0 0 6 1980
Size 512 .. 1023 0 0 0 0
Size 1024 .. 2047 500 759000 500 759000
Size 2048 .. 4095 0 0 0 0
Size 4096 .. 8191 0 0 0 0
Size >= 8192 0 0 0 0
在大小的一增加由一个字节导致分段(> 1500)，因此500数据包被发送作为两套500数据包。在本例中ping发生故障的注释。这比已配置的MTU很可能归结于的网络能处理大小极大，但是那不是此条款焦点。
[ECS]ASR5500> ping 10.213.137.1 size 1473 flood
Friday July 17 23:53:55 UTC 2015
PING 10.213.137.1 (10.213.137.1) 1473(1501) bytes of data.
................................................................................
................................................................................
................................................................................
................................................................................
................................................................................
................................................................................
....................^C
--- 10.213.137.1 ping statistics ---
500 packets transmitted, 0 received, 100% packet loss, time 7124ms
, ipg/ewma 14.277/0.000 ms
[ECS]ASR5500> show port datalink counters 5/29
Friday July 17 23:54:05 UTC 2015
Counters for port 5/29:
Line Card 10 Gigabit Ethernet Port
Rx Counter Data | Tx Counter Data
----------------------- -------------- + ----------------------- -------------
RX Bytes 786615 | TX Bytes 1566628
RX Unicast frames 601 | TX Unicast frames 1567
RX Multicast frames 111 | TX Multicast frames 0
RX Broadcast frames 47 | TX Broadcast frames 0
RX Size 64 frames 0 | TX Size 64 frames 501
RX Size 65 .. 127 fr 190 | TX Size 65 .. 127 fr 2
RX Size 128 .. 255 fr 64 | TX Size 128 .. 255 fr 48
RX Size 256 .. 511 fr 5 | TX Size 256 .. 511 fr 16
RX Size 512 .. 1023 fr 0 | TX Size 512 .. 1023 fr 0
RX Size 1024 .. 1518 fr 0 | TX Size 1024 .. 1518 fr 0
RX Size 1519 .. 1522 fr 500 | TX Size 1519 .. 1522 fr 1000
RX ExceedMaxSize frames 0
RX Fragment frames 0 | TX Fragment frames 0
RX Jabber frames 0 | TX Jabber frames 0
RX Control frames 0 | TX Control frames 0
RX Pause frames 0 | TX Pause frames 0
RX FCS Error frames 0 | TX FCS Error frames 0
RX Length Error frames 0 | TX Length Error frames 0
RX Code Error frames 0
RX ExMaxSize Err frames 0
----------------------- -------------- + ----------------------- -------------
[ECS]ASR5500> show port npu counters 5/29 vlan 31
Friday July 17 23:54:06 UTC 2015
Counters for port 5/29 vlan id 31:
Counter Rx Frames Rx Bytes Tx Frames Tx Bytes
-------------------- ------------- --------------- ------------- ---------------
Unicast 554 766984 1562 1549040
Multicast 94 6962 0 0
Broadcast 53 4294 0 0
IPv4 unicast 607 771278 1562 1549040
IPv4 non-unicast 73 4904 0 0
IPv6 unicast 0 0 0 0
IPv6 non-unicast 21 2058 0 0
Fragments received 0 0 n/a n/a
Packets reassembled 0 0 n/a n/a
Fragments to kernel 0 0 n/a n/a
HW error 0 0 n/a n/a
Port non-operational 25146 1805666 0 0
SRC MAC is multicast 0 0 n/a n/a
Unknown VLAN tag 0 0 n/a n/a
Other protocols 68 4742 n/a n/a
Not IPv4 21 2058 n/a n/a
...
Size 0 .. 63 0 0 501 19546
Size 64 .. 127 188 14154 2 140
Size 128 .. 255 60 8520 45 6450
Size 256 .. 511 0 0 15 4950
Size 512 .. 1023 0 0 0 0
Size 1024 .. 2047 500 759000 1000 1518000
Size 2048 .. 4095 0 0 0 0
Size 4096 .. 8191 0 0 0 0
Size >= 8192 0 0 0 0
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