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本文檔介紹在配備運行NX-OS軟體的Cisco Scale ASIC的Cisco Nexus 9000系列交換機上的排隊和緩衝。
思科建議您瞭解共用介質網路上乙太網交換的基本知識,以及這些網路中佇列/緩衝的必要性。思科還建議您瞭解Cisco Nexus交換機上的服務品質(QoS)和緩衝的基礎知識。如需詳細資訊,請參閱以下檔案:
本檔案中的資訊是根據執行NX-OS軟體版本9.3(8)的Cloud Scale ASIC的Cisco Nexus 9000系列交換器。
本文檔中介紹的過程僅適用於此處顯示的硬體。
本文中的資訊是根據特定實驗室環境內的裝置所建立。文中使用到的所有裝置皆從已清除(預設)的組態來啟動。如果您的網路運作中,請確保您瞭解任何指令可能造成的影響。
本文檔介紹在配備運行NX-OS軟體的Cisco Cloud Scale ASIC(應用專用積體電路)的Cisco Nexus 9000系列交換機上進行排隊和緩衝的機理。本檔案還說明此平台上的連線埠超額訂閱的症狀,例如非零輸出捨棄介面計數器和表示已超出緩衝區臨界值的syslogs。
採用Cisco Cloud Scale ASIC的Cisco Nexus 9000系列交換機實施了「共用記憶體」出口緩衝區架構。ASIC分為一個或多個「片」。每個片都有自己的緩衝區,並且只有該片中的埠可以使用該緩衝區。在物理上,每個片被劃分為「單元」,表示緩衝區的部分。切片被劃分為「池組」。為每個pool-group分配一定數量的信元,並且這些信元不會在單獨的pool-group之間共用。每個池組都有一個或多個「池」,這些池表示單播或組播流量的服務類別(CoS)。這有助於每個池組保證池組所服務的流量型別的緩衝區資源。
此處的影象直觀地演示了各種思科雲規模ASIC模型如何劃分成多個切片。該影象還演示了如何通過單元格為每個切片分配一定量的緩衝區。
Nexus 9000系列交換機和Nexus 9500線卡的每個型號內部都有不同數量的Cisco Cloud Scale ASIC,以及不同的佈局,這些佈局規定了哪些前面板埠連線到哪個ASIC。以下影象顯示了使用N9K-X9736C-FX線卡和N9K-C9336C-FX2交換機的兩個示例。
N9K-C9736C-FX線卡具有4個思科雲擴展LS1800FX ASIC,每個ASIC具有一個片。在內部,每個ASIC都稱為「單元」。每個扇區稱為「例項」,並分配一個從零開始的整數,用於唯一標識機箱內的該扇區。這將產生如下所示的置換:
N9K-C9336C-FX2交換機具有一個Cisco Cloud Scale LS3600FX2 ASIC,每個ASIC有兩個片。在內部,每個ASIC都稱為「單元」。每個扇區稱為「例項」,並分配一個從零開始的整數,用於唯一標識機箱內的該扇區。這將產生如下所示的置換:
每個線卡和交換機都具有不同的佈局,從而導致不同的例項編號。要圍繞頻寬密集型流量設計網路,您需要瞭解要使用的交換機或線卡佈局。show interface hardware-mappings命令可用於將每個前面板埠關聯到裝置(ASIC)和扇區號。這裡顯示了一個示例,其中Nexus 9504交換機的介面Ethernet2/16與機箱插槽2中插入的N9K-X9736C-FX線卡對映到單元1,片0。
switch# show interface hardware-mappings Legends: SMod - Source Mod. 0 is N/A Unit - Unit on which port resides. N/A for port channels HPort - Hardware Port Number or Hardware Trunk Id: HName - Hardware port name. None means N/A FPort - Fabric facing port number. 255 means N/A NPort - Front panel port number VPort - Virtual Port Number. -1 means N/A Slice - Slice Number. N/A for BCM systems SPort - Port Number wrt Slice. N/A for BCM systems SrcId - Source Id Number. N/A for BCM systems MacIdx - Mac index. N/A for BCM systems MacSubPort - Mac sub port. N/A for BCM systems ------------------------------------------------------------------------------------------------------- Name Ifindex Smod Unit HPort FPort NPort VPort Slice SPort SrcId MacId MacSP VIF Block BlkSrcID ------------------------------------------------------------------------------------------------------- Eth2/1 1a080000 5 0 16 255 0 -1 0 16 32 4 0 145 0 32 Eth2/2 1a080200 5 0 12 255 4 -1 0 12 24 3 0 149 0 24 Eth2/3 1a080400 5 0 8 255 8 -1 0 8 16 2 0 153 0 16 Eth2/4 1a080600 5 0 4 255 12 -1 0 4 8 1 0 157 0 8 Eth2/5 1a080800 5 0 0 255 16 -1 0 0 0 0 0 161 0 0 Eth2/6 1a080a00 5 0 56 255 20 -1 0 56 112 14 0 165 1 40 Eth2/7 1a080c00 5 0 52 255 24 -1 0 52 104 13 0 169 1 32 Eth2/8 1a080e00 6 1 16 255 28 -1 0 16 32 4 0 173 0 32 Eth2/9 1a081000 6 1 12 255 32 -1 0 12 24 3 0 177 0 24 Eth2/10 1a081200 6 1 8 255 36 -1 0 8 16 2 0 181 0 16 Eth2/11 1a081400 6 1 4 255 40 -1 0 4 8 1 0 185 0 8 Eth2/12 1a081600 6 1 0 255 44 -1 0 0 0 0 0 189 0 0 Eth2/13 1a081800 6 1 56 255 48 -1 0 56 112 14 0 193 1 40 Eth2/14 1a081a00 6 1 52 255 52 -1 0 52 104 13 0 197 1 32 Eth2/15 1a081c00 7 2 16 255 56 -1 0 16 32 4 0 201 0 32 Eth2/16 1a081e00 7 2 12 255 60 -1 0 12 24 3 0 205 0 24 Eth2/17 1a082000 7 2 8 255 64 -1 0 8 16 2 0 209 0 16 Eth2/18 1a082200 7 2 4 255 68 -1 0 4 8 1 0 213 0 8 Eth2/19 1a082400 7 2 0 255 72 -1 0 0 0 0 0 217 0 0 Eth2/20 1a082600 7 2 56 255 76 -1 0 56 112 14 0 221 1 40 Eth2/21 1a082800 7 2 52 255 80 -1 0 52 104 13 0 225 1 32 Eth2/22 1a082a00 8 3 16 255 84 -1 0 16 32 4 0 229 0 32 Eth2/23 1a082c00 8 3 12 255 88 -1 0 12 24 3 0 233 0 24 Eth2/24 1a082e00 8 3 8 255 92 -1 0 8 16 2 0 237 0 16 Eth2/25 1a083000 8 3 4 255 96 -1 0 4 8 1 0 241 0 8 Eth2/26 1a083200 8 3 0 255 100 -1 0 0 0 0 0 245 0 0 Eth2/27 1a083400 8 3 56 255 104 -1 0 56 112 14 0 249 1 40 Eth2/28 1a083600 8 3 52 255 108 -1 0 52 104 13 0 253 1 32 Eth2/29 1a083800 5 0 48 255 112 -1 0 48 96 12 0 257 1 24 Eth2/30 1a083a00 5 0 44 255 116 -1 0 44 88 11 0 261 1 16 Eth2/31 1a083c00 6 1 48 255 120 -1 0 48 96 12 0 265 1 24 Eth2/32 1a083e00 6 1 44 255 124 -1 0 44 88 11 0 269 1 16 Eth2/33 1a084000 7 2 48 255 128 -1 0 48 96 12 0 273 1 24 Eth2/34 1a084200 7 2 44 255 132 -1 0 44 88 11 0 277 1 16 Eth2/35 1a084400 8 3 48 255 136 -1 0 48 96 12 0 281 1 24 Eth2/36 1a084600 8 3 44 255 140 -1 0 44 88 11 0 285 1 16
解釋系統日誌時,系統會根據連續單元和片組合順序計算例項ID。 例如,如果Nexus 9500模組或Nexus 9300 TOR(架頂式)有兩個單元(ASIC)和每個單元兩個扇區,則例項ID可以如下所示:
如果一個模組具有一個單元及四個片,則例項ID可以是:
連線到乙太網絡的介面一次只能傳輸一個資料包。當兩個封包需要同時輸出一個乙太網路介面時,乙太網路介面會傳輸一個封包,同時緩衝另一個封包。一旦傳送了第一封包,乙太網介面就從緩衝區傳送第二封包。當需要輸出的總流量超過介面頻寬時,介面被視為超額訂用。例如,如果總共有15Gbps的流量即時進入交換機並需要輸出10Gbps介面,則10Gbps介面由於無法一次傳輸15Gbps流量而超額使用。
具有雲規模ASIC的Cisco Nexus 9000系列交換機通過在與出口介面關聯的ASIC分割槽的緩衝區中緩沖流量來處理此資源爭用。如果需要輸出介面的總流量在一段延長的時間內超過介面頻寬,則ASIC分片的緩衝區將開始填充需要輸出介面的資料包。
當ASIC分片的緩衝區達到90%的利用率時,交換機將生成類似於下面所示的系統日誌:
%TAHUSD-SLOT2-4-BUFFER_THRESHOLD_EXCEEDED: Module 2 Instance 0 Pool-group buffer 90 percent threshold is exceeded!
當ASIC分段的緩衝區完全滿時,交換器會捨棄需要輸出介面的所有額外流量,直到緩衝區中的空間變為空閒。交換器捨棄此流量時,會增加輸出介面上的Output Discards計數器。
生成的syslog和非零Output Discards計數器都是超訂用介面的症狀。每個症狀都將在本部分的各個小節中詳細探討。
此處顯示了BUFFER_THRESHOLD_EXCEEDED系統日誌的示例。
%TAHUSD-SLOTX-4-BUFFER_THRESHOLD_EXCEEDED: Module X Instance Y Pool-group buffer Z percent threshold is exceeded!
此系統日誌包含三個關鍵資訊:
Output Discards介面計數器指示必須已經離開介面但由於ASIC片緩衝區已滿且無法接受新資料包而無法丟棄的資料包數量。Output Discards計數器在show interface和show interface counters errors的輸出中可見,如下所示。
switch# show interface Ethernet1/1 Ethernet1/1 is up admin state is up, Dedicated Interface Hardware: 1000/10000/25000/40000/50000/100000 Ethernet, address: 7cad.4f6d.f6d8 (bia 7cad.4f6d.f6d8) MTU 1500 bytes, BW 40000000 Kbit , DLY 10 usec reliability 255/255, txload 232/255, rxload 1/255 Encapsulation ARPA, medium is broadcast Port mode is trunk full-duplex, 40 Gb/s, media type is 40G Beacon is turned off Auto-Negotiation is turned on FEC mode is Auto Input flow-control is off, output flow-control is off Auto-mdix is turned off Rate mode is dedicated Switchport monitor is off EtherType is 0x8100 EEE (efficient-ethernet) : n/a admin fec state is auto, oper fec state is off Last link flapped 03:16:50 Last clearing of "show interface" counters never 3 interface resets Load-Interval #1: 30 seconds 30 seconds input rate 0 bits/sec, 0 packets/sec 30 seconds output rate 36503585488 bits/sec, 3033870 packets/sec input rate 0 bps, 0 pps; output rate 36.50 Gbps, 3.03 Mpps Load-Interval #2: 5 minute (300 seconds) 300 seconds input rate 32 bits/sec, 0 packets/sec 300 seconds output rate 39094683384 bits/sec, 3249159 packets/sec input rate 32 bps, 0 pps; output rate 39.09 Gbps, 3.25 Mpps RX 0 unicast packets 208 multicast packets 9 broadcast packets 217 input packets 50912 bytes 0 jumbo packets 0 storm suppression bytes 0 runts 0 giants 0 CRC 0 no buffer 0 input error 0 short frame 0 overrun 0 underrun 0 ignored 0 watchdog 0 bad etype drop 0 bad proto drop 0 if down drop 0 input with dribble 0 input discard 0 Rx pause TX 38298127762 unicast packets 6118 multicast packets 0 broadcast packets 38298133880 output packets 57600384931480 bytes 0 jumbo packets 0 output error 0 collision 0 deferred 0 late collision 0 lost carrier 0 no carrier 0 babble 57443534227 output discard <<< Output discards due to oversubcription 0 Tx pause switch# show interface Ethernet1/1 counters errors -------------------------------------------------------------------------------- Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize OutDiscards -------------------------------------------------------------------------------- Eth1/1 0 0 0 0 0 57443534227 -------------------------------------------------------------------------------- Port Single-Col Multi-Col Late-Col Exces-Col Carri-Sen Runts -------------------------------------------------------------------------------- Eth1/1 0 0 0 0 0 0 -------------------------------------------------------------------------------- Port Giants SQETest-Err Deferred-Tx IntMacTx-Er IntMacRx-Er Symbol-Err -------------------------------------------------------------------------------- Eth1/1 0 -- 0 0 0 0 -------------------------------------------------------------------------------- Port InDiscards -------------------------------------------------------------------------------- Eth1/1 0
考慮以下場景:兩個IXIA流量生成器之間的流量經過在機箱插槽1和2中插入兩個N9K-X9736C-FX線卡的Nexus 9504交換機。100Gbps流量通過100Gbps介面Ethernet1/1進入交換機,需要輸出40Gbps介面Ethernet2/2。因此,Ethernet2/2為超額使用。此方案的拓撲如圖所示。
由於Nexus 9000雲規模ASIC使用共用記憶體出口緩衝區架構,您必須檢查出口介面Ethernet2/2的緩衝區以檢視擁塞。在本例中,插入插槽2中的線卡是輸出線卡,因此您必須先使用attach module 2命令,然後使用show hardware internal tah buffer counters命令檢視內部硬體緩衝區。請注意Unit 0、Slice 0 pool-group和相關池的非零「Occupancy drops」計數器,它指示由於池組緩衝區已完全佔用而丟棄的資料包數。
switch# attach module 2
module-2# show hardware internal tah buffer counters Unit: 0 Slice: 0 ==================== |------------------------------------------------------------------------------------------------------------------| | Output Pool-Group drops | | Drop-PG No-drop CPU--PG LCPU-PG RCPU-PG SPAN-PG | |------------------------------------------------------------------------------------------------------------------| Occupancy drops 51152554987 0 0 0 0 0 | AQM drops 0 0 N/A N/A N/A N/A | |--------------------------------------------------------------------------------------------------------------------| | Output UC Pool counters | | Pool 0 Pool 1 Pool 2 Pool 3 Pool 4 Pool 5 Pool 6 Pool 7 | |--------------------------------------------------------------------------------------------------------------------| Dynamic Threshold (cells) 93554 93554 93554 93554 93554 93554 93554 93554 | Occupancy drops 51152555398 0 0 0 0 0 0 0 | AQM drops 0 0 0 0 0 0 0 0 | |--------------------------------------------------------------------------------------------------------------------| | Output MC Pool counters | | Pool 0 Pool 1 Pool 2 Pool 3 Pool 4 Pool 5 Pool 6 Pool 7 | |--------------------------------------------------------------------------------------------------------------------| Dynamic Threshold (cells) 93554 93554 93554 93554 93554 93554 93554 93554 | Dynamic Threshold (desc) 93554 93554 93554 93554 93554 93554 93554 93554 | Dynamic Threshold (inq thr) 64035 64035 64035 64035 64035 64035 64035 64035 | Occupancy drops 0 0 0 0 0 0 0 0 | |--------------+---------+---------+---------+---------+---------+--------+---------+---------+| | Additional counters | |--------------+---------+---------+---------+---------+---------+--------+---------+---------+| MEM cell drop reason : 0 MEM descriptor drop reason : 0 OPG cell drop reason : 0 OPG descriptor drop reason : 0 OPG CPU cell drop reason : 0 OPG CPU descriptor drop reason : 0 OPG SPAN cell drop reason : 0 OPG SPAN descriptor drop reason : 0 OPOOL cell drop reason : 0 OPOOL descriptor drop reason : 0 UC OQUEUE cell drop reason : 51152556479 MC OQUEUE cell drop reason : 27573307 OQUEUE descriptor drop reason : 0 MC OPOOL cell drop reason : 0 FWD DROP : 15 SOD : 0 BMM BP : 0 No Drop : 0 Packets received : 87480806439 TRUNC MTU : 0 TRUNK BMM BP : 0 VOQFC messages sent : 0 SOD messages sent : 0 SPAN desciptor drop : 0 Unit: 1 Slice: 0 ==================== |------------------------------------------------------------------------------------------------------------------| | Output Pool-Group drops | | Drop-PG No-drop CPU--PG LCPU-PG RCPU-PG SPAN-PG | |------------------------------------------------------------------------------------------------------------------| Occupancy drops 0 0 0 0 0 0 | AQM drops 0 0 N/A N/A N/A N/A | |--------------------------------------------------------------------------------------------------------------------| | Output UC Pool counters | | Pool 0 Pool 1 Pool 2 Pool 3 Pool 4 Pool 5 Pool 6 Pool 7 | |--------------------------------------------------------------------------------------------------------------------| Dynamic Threshold (cells) 93554 93554 93554 93554 93554 93554 93554 93554 | Occupancy drops 0 0 0 0 0 0 0 0 | AQM drops 0 0 0 0 0 0 0 0 | |--------------------------------------------------------------------------------------------------------------------| | Output MC Pool counters | | Pool 0 Pool 1 Pool 2 Pool 3 Pool 4 Pool 5 Pool 6 Pool 7 | |--------------------------------------------------------------------------------------------------------------------| Dynamic Threshold (cells) 93554 93554 93554 93554 93554 93554 93554 93554 | Dynamic Threshold (desc) 93554 93554 93554 93554 93554 93554 93554 93554 | Dynamic Threshold (inq thr) 64035 64035 64035 64035 64035 64035 64035 64035 | Occupancy drops 0 0 0 0 0 0 0 0 | |--------------+---------+---------+---------+---------+---------+--------+---------+---------+| | Additional counters | |--------------+---------+---------+---------+---------+---------+--------+---------+---------+| MEM cell drop reason : 0 MEM descriptor drop reason : 0 OPG cell drop reason : 0 OPG descriptor drop reason : 0 OPG CPU cell drop reason : 0 OPG CPU descriptor drop reason : 0 OPG SPAN cell drop reason : 0 OPG SPAN descriptor drop reason : 0 OPOOL cell drop reason : 0 OPOOL descriptor drop reason : 0 UC OQUEUE cell drop reason : 0 MC OQUEUE cell drop reason : 0 OQUEUE descriptor drop reason : 0 MC OPOOL cell drop reason : 0 FWD DROP : 8 SOD : 0 BMM BP : 0 No Drop : 0 Packets received : 45981341 TRUNC MTU : 0 TRUNK BMM BP : 0 VOQFC messages sent : 0 SOD messages sent : 0 SPAN desciptor drop : 0
每個ASIC單元/切片元組都通過唯一標識的「例項」表示。show hardware internal buffer info pkt-stats命令的輸出顯示每個例項的擁塞池組(縮寫為「PG」)的詳細資訊。此命令還顯示緩衝區中已使用的單元格的歷史峰值/最大數量。最後,該命令顯示具有緩沖流量的埠的雲規模ASIC埠識別符號的即時快照。此命令示例如下。
switch# attach module 2
module-2# show hardware internal buffer info pkt-stats Instance 0 ============ |------------------------------------------------------------------------------------------------------------| | Output Pool-Group Buffer Utilization (cells/desc) | | Drop-PG No-drop CPU--PG LCPU-PG RCPU-PG SPAN-PG | |------------------------------------------------------------------------------------------------------------| Total Instant Usage (cells) 59992 0 0 0 0 0 | Remaining Instant Usage (cells) 33562 0 1500 250 1500 1500 | Peak/Max Cells Used 90415 0 N/A N/A N/A N/A | Switch Cells Count 93554 0 1500 250 1500 1500 | Total Instant Usage (desc) 0 0 0 0 0 0 | Remaining Instant Usage (desc) 93554 0 1500 250 1500 1500 | Switch Desc Count 93554 0 1500 250 1500 1500 | |--------------------------------------------------------------------------------------------------------------------| | Output UC Pool Buffer Utilization (cells/desc) | | Pool 0 Pool 1 Pool 2 Pool 3 Pool 4 Pool 5 Pool 6 Pool 7 | |--------------------------------------------------------------------------------------------------------------------| Total Instant Usage (cells) 60027 0 0 0 0 0 0 0 | Total Instant Usage (desc) 0 0 0 0 0 0 0 0 | Peak/Max Cells Used 62047 0 0 0 0 0 0 0 | |--------------------------------------------------------------------------------------------------------------------| | Output MC Pool Buffer Utilization (cells/desc) | | Pool 0 Pool 1 Pool 2 Pool 3 Pool 4 Pool 5 Pool 6 Pool 7 | |--------------------------------------------------------------------------------------------------------------------| Total Instant Usage (cells) 0 0 0 0 0 0 0 0 | Total Instant Usage (desc) 0 0 0 0 0 0 0 0 | Total Instant Usage (inq cells) 0 0 0 0 0 0 0 0 | Total Instant Usage (packets) 0 0 0 0 0 0 0 0 | Peak/Max Cells Used 60399 0 0 0 0 0 0 0 | |--------------------------------------------------------------------------| | Instant Buffer utilization per queue per port | | Each line displays the number of cells/desc utilized for a given | | port for each QoS queue | | One cell represents approximately 416 bytes | |--------------+---------+---------+---------+---------+---------+--------+---------+---------+| |ASIC Port Q7 Q6 Q5 Q4 Q3 Q2 Q1 Q0 | |--------------+---------+---------+---------+---------+---------+--------+---------+---------+| [12] <<< ASIC Port 12 in Unit 0 Instance 0 is likely the congested egress interface UC-> 0 0 0 0 0 0 0 59988 | MC cells-> 0 0 0 0 0 0 0 0 | MC desc-> 0 0 0 0 0 0 0 0 |
另請參閱命令的峰值變化。使用此命令將系統日誌與特定池組、池或埠中的潛在峰值相關聯。
switch# show hardware internal buffer info pkt-stats peak slot 1 ======= Instance 0 ============ |--------------+---------+---------+---------+---------+---------+| | Pool-Group Peak counters | |--------------+---------+---------+---------+---------+---------+| Drop PG : 0 No-drop PG : 0 |--------------+---------+---------+---------+---------+---------+| | Pool Peak counters | |--------------+---------+---------+---------+---------+---------+| MC Pool 0 : 0 MC Pool 1 : 0 MC Pool 2 : 0 MC Pool 3 : 0 MC Pool 4 : 0 MC Pool 5 : 0 MC Pool 6 : 0 MC Pool 7 : 0 UC Pool 0 : 0 UC Pool 1 : 0 UC Pool 2 : 0 UC Pool 3 : 0 UC Pool 4 : 0 UC Pool 5 : 0 UC Pool 6 : 0 UC Pool 7 : 0 |--------------+---------+---------+---------+---------+---------+| | Port Peak counters | | classes mapped to count_0: 0 1 2 3 4 5 6 7 | classes mapped to count_1: None |--------------+---------+---------+---------+---------+---------+| [0] <<< ASIC Port. This can be checked via "show hardware interface-mappings" count_0 : 0 count_1 : 0 [1] count_0 : 0 count_1 : 0
show interface hardware-mappings命令可用於將Cloud Scale ASIC埠識別符號轉換為前面板埠。在前面的示例中,與片/例項0上的ASIC單元0關聯的ASIC埠12(由show interface hardware-mappings輸出中的SPort列表示)具有59,988個佔用的單元,每個單元為416個位元組。此處顯示了show interface hardware-mappings命令的示例,該命令將該介面對映到前面板埠Ethernet2/2。
switch# show interface hardware-mappings Legends: SMod - Source Mod. 0 is N/A Unit - Unit on which port resides. N/A for port channels HPort - Hardware Port Number or Hardware Trunk Id: HName - Hardware port name. None means N/A FPort - Fabric facing port number. 255 means N/A NPort - Front panel port number VPort - Virtual Port Number. -1 means N/A Slice - Slice Number. N/A for BCM systems SPort - Port Number wrt Slice. N/A for BCM systems SrcId - Source Id Number. N/A for BCM systems MacIdx - Mac index. N/A for BCM systems MacSubPort - Mac sub port. N/A for BCM systems ------------------------------------------------------------------------------------------------------- Name Ifindex Smod Unit HPortFPort NPort VPort Slice SPort SrcId MacId MacSP VIF Block BlkSrcID ------------------------------------------------------------------------------------------------------- Eth2/2 1a080200 5 0 12 255 4 -1 0 12 24 3 0 149 0 24
我們可以使用show queuing interface命令進一步將介面Ethernet2/2的超訂用與QoS隊列丟棄相關聯。此步驟的範例如下所示。
switch# show queuing interface Ethernet2/2 Egress Queuing for Ethernet2/2 [System] ------------------------------------------------------------------------------ QoS-Group# Bandwidth% PrioLevel Shape QLimit Min Max Units ------------------------------------------------------------------------------ 7 - 1 - - - 9(D) 6 0 - - - - 9(D) 5 0 - - - - 9(D) 4 0 - - - - 9(D) 3 0 - - - - 9(D) 2 0 - - - - 9(D) 1 0 - - - - 9(D) 0 100 - - - - 9(D) +-------------------------------------------------------------+ | QOS GROUP 0 | +-------------------------------------------------------------+ | | Unicast |Multicast | +-------------------------------------------------------------+ | Tx Pkts | 35593332351| 18407162| | Tx Byts | 53532371857088| 27684371648| | WRED/AFD & Tail Drop Pkts | 53390604466| 27573307| | WRED/AFD & Tail Drop Byts | 80299469116864| 110293228| | Q Depth Byts | 24961664| 0| | WD & Tail Drop Pkts | 53390604466| 27573307| +-------------------------------------------------------------+ | QOS GROUP 1 | +-------------------------------------------------------------+ | | Unicast |Multicast | +-------------------------------------------------------------+ | Tx Pkts | 0| 0| | Tx Byts | 0| 0| | WRED/AFD & Tail Drop Pkts | 0| 0| | WRED/AFD & Tail Drop Byts | 0| 0| | Q Depth Byts | 0| 0| | WD & Tail Drop Pkts | 0| 0| +-------------------------------------------------------------+ | QOS GROUP 2 | +-------------------------------------------------------------+ | | Unicast |Multicast | +-------------------------------------------------------------+ | Tx Pkts | 0| 0| | Tx Byts | 0| 0| | WRED/AFD & Tail Drop Pkts | 0| 0| | WRED/AFD & Tail Drop Byts | 0| 0| | Q Depth Byts | 0| 0| | WD & Tail Drop Pkts | 0| 0| +-------------------------------------------------------------+ | QOS GROUP 3 | +-------------------------------------------------------------+ | | Unicast |Multicast | +-------------------------------------------------------------+ | Tx Pkts | 0| 0| | Tx Byts | 0| 0| | WRED/AFD & Tail Drop Pkts | 0| 0| | WRED/AFD & Tail Drop Byts | 0| 0| | Q Depth Byts | 0| 0| | WD & Tail Drop Pkts | 0| 0| +-------------------------------------------------------------+ | QOS GROUP 4 | +-------------------------------------------------------------+ | | Unicast |Multicast | +-------------------------------------------------------------+ | Tx Pkts | 0| 0| | Tx Byts | 0| 0| | WRED/AFD & Tail Drop Pkts | 0| 0| | WRED/AFD & Tail Drop Byts | 0| 0| | Q Depth Byts | 0| 0| | WD & Tail Drop Pkts | 0| 0| +-------------------------------------------------------------+ | QOS GROUP 5 | +-------------------------------------------------------------+ | | Unicast |Multicast | +-------------------------------------------------------------+ | Tx Pkts | 0| 0| | Tx Byts | 0| 0| | WRED/AFD & Tail Drop Pkts | 0| 0| | WRED/AFD & Tail Drop Byts | 0| 0| | Q Depth Byts | 0| 0| | WD & Tail Drop Pkts | 0| 0| +-------------------------------------------------------------+ | QOS GROUP 6 | +-------------------------------------------------------------+ | | Unicast |Multicast | +-------------------------------------------------------------+ | Tx Pkts | 0| 0| | Tx Byts | 0| 0| | WRED/AFD & Tail Drop Pkts | 0| 0| | WRED/AFD & Tail Drop Byts | 0| 0| | Q Depth Byts | 0| 0| | WD & Tail Drop Pkts | 0| 0| +-------------------------------------------------------------+ | QOS GROUP 7 | +-------------------------------------------------------------+ | | Unicast |Multicast | +-------------------------------------------------------------+ | Tx Pkts | 0| 0| | Tx Byts | 0| 0| | WRED/AFD & Tail Drop Pkts | 0| 0| | WRED/AFD & Tail Drop Byts | 0| 0| | Q Depth Byts | 0| 0| | WD & Tail Drop Pkts | 0| 0| +-------------------------------------------------------------+ | CONTROL QOS GROUP | +-------------------------------------------------------------+ | | Unicast |Multicast | +-------------------------------------------------------------+ | Tx Pkts | 5704| 0| | Tx Byts | 725030| 0| | Tail Drop Pkts | 0| 0| | Tail Drop Byts | 0| 0| +-------------------------------------------------------------+ | SPAN QOS GROUP | +-------------------------------------------------------------+ | | Unicast |Multicast | +-------------------------------------------------------------+ | Tx Pkts | 0| 0| | Tx Byts | 0| 0| +-------------------------------------------------------------+ Per Slice Egress SPAN Statistics --------------------------------------------------------------- SPAN Copies Tail Drop Pkts 0 SPAN Input Queue Drop Pkts 0 SPAN Copies/Transit Tail Drop Pkts 0 SPAN Input Desc Drop Pkts 0
最後,您可以使用show interface指令驗證輸出介面Ethernet2/2是否具有非零輸出捨棄計數器。此步驟的範例如下所示。
switch# show interface Ethernet2/2 Ethernet2/2 is up admin state is up, Dedicated Interface Hardware: 1000/10000/25000/40000/50000/100000 Ethernet, address: 7cad.4f6d.f6d8 (bia 7cad.4f6d.f6d8) MTU 1500 bytes, BW 40000000 Kbit , DLY 10 usec reliability 255/255, txload 232/255, rxload 1/255 Encapsulation ARPA, medium is broadcast Port mode is trunk full-duplex, 40 Gb/s, media type is 40G Beacon is turned off Auto-Negotiation is turned on FEC mode is Auto Input flow-control is off, output flow-control is off Auto-mdix is turned off Rate mode is dedicated Switchport monitor is off EtherType is 0x8100 EEE (efficient-ethernet) : n/a admin fec state is auto, oper fec state is off Last link flapped 03:16:50 Last clearing of "show interface" counters never 3 interface resets Load-Interval #1: 30 seconds 30 seconds input rate 0 bits/sec, 0 packets/sec 30 seconds output rate 36503585488 bits/sec, 3033870 packets/sec input rate 0 bps, 0 pps; output rate 36.50 Gbps, 3.03 Mpps Load-Interval #2: 5 minute (300 seconds) 300 seconds input rate 32 bits/sec, 0 packets/sec 300 seconds output rate 39094683384 bits/sec, 3249159 packets/sec input rate 32 bps, 0 pps; output rate 39.09 Gbps, 3.25 Mpps RX 0 unicast packets 208 multicast packets 9 broadcast packets 217 input packets 50912 bytes 0 jumbo packets 0 storm suppression bytes 0 runts 0 giants 0 CRC 0 no buffer 0 input error 0 short frame 0 overrun 0 underrun 0 ignored 0 watchdog 0 bad etype drop 0 bad proto drop 0 if down drop 0 input with dribble 0 input discard 0 Rx pause TX 38298127762 unicast packets 6118 multicast packets 0 broadcast packets 38298133880 output packets 57600384931480 bytes 0 jumbo packets 0 output error 0 collision 0 deferred 0 late collision 0 lost carrier 0 no carrier 0 babble 57443534227 output discard <<< Output discards due to oversubcription 0 Tx pause
如果您觀察到具有雲規模ASIC的Nexus 9000系列交換機上的輸出丟棄,可以使用以下一種或多種方法解決問題:
本文此節包含有關遇到BUFFER_THRESHOLD_EXCEEDED系統日誌、網路擁塞/超訂用情形和增量輸出丟棄介面計數器時採取的後續步驟的其他資訊。
您可以修改系統緩衝區狀態輪詢間隔,該間隔控制系統輪詢當前ASIC片緩衝區利用率的頻率。這通過hardware profile buffer info poll-interval global configuration命令來完成。預設配置值為5,000毫秒。可以全域性修改此配置,也可以按模組修改此配置。此處顯示此組態指令的範例,其中將其修改為值1,000毫秒。
switch# configure terminal Enter configuration commands, one per line. End with CNTL/Z. switch(config)# hardware profile buffer info poll-interval timer 1000 switch(config)# end switch# show running-config | include hardware.profile.buffer hardware profile buffer info poll-interval timer 1000 switch#
您可以修改埠出口緩衝區使用閾值,該閾值控制系統何時生成BUFFER_THRESHOLD_EXCEEDED系統日誌指示表示ASIC片緩衝區利用率已超出配置的閾值。這是使用hardware profile buffer info port-threshold全域性配置命令完成的。預設配置值為90%。可以全域性修改此配置,也可以按模組修改此配置。此處範例顯示了此組態命令,其中將其修改為值80%。
switch# configure terminal Enter configuration commands, one per line. End with CNTL/Z. switch(config)# hardware profile buffer info port-threshold threshold 80 switch(config)# end switch# show running-config | include hardware.profile.buffer hardware profile buffer info port-threshold threshold 80 switch#
可以修改交換機生成的BUFFER_THRESHOLD_EXCEEDED系統日誌之間的最小間隔。您也可以完全禁用BUFFER_THRESHOLD_EXCEEDED系統日誌。這是使用hardware profile buffer info syslog-interval timer全域性配置命令完成的。預設配置值為120秒。通過將值設定為0秒,可以完全禁用系統日誌。此處範例顯示此組態命令,其中系統日誌已完全停用。
switch# configure terminal Enter configuration commands, one per line. End with CNTL/Z. switch(config)# hardware profile buffer info syslog-interval timer 0 switch(config)# end switch# show running-config | include hardware.profile.buffer hardware profile buffer info syslog-interval timer 0 switch#
除了本文檔中列出的命令以外,您還可以收集此處顯示的受網路擁塞情況影響的交換機的日誌,以識別擁塞的出口介面。
如果擁塞或超訂用發生在很短的時間間隔(微突發)內,則需要其他資訊來準確描述超訂用對交換器的影響。
配備Cisco Cloud Scale ASIC的Cisco Nexus 9000系列交換機可以監控微突發流量,這些微突發可導致您的環境中出現臨時網路擁塞和流量丟失。有關微脈衝串以及如何配置此功能的詳細資訊,請參閱此處顯示的文檔:
修訂 | 發佈日期 | 意見 |
---|---|---|
6.0 |
09-Nov-2023 |
更新 |
5.0 |
04-Oct-2023 |
重新認證 |
3.0 |
21-Jan-2022 |
將「後續步驟」部分新增到文檔。 |
2.0 |
03-Oct-2021 |
更新適用硬體部分以包括新硬體。 |
1.0 |
31-Aug-2021 |
初始版本 |