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Unusual CPU Usage on 3750G

Hello, we have a Cisco WS-C3750G-24T running IOS 12.2(25)SEE (image C3750-IPSERVICESK9-M). We have this device running layer-3 services for a few hosts, and total throughput is probably around 300Mbps peak for the whole network. The setup is very simple, and this device is one of two devices on the network that is running OSPF. The other is our border router, which also runs BGP.

We are seeing very unusual CPU usage on this 3750G. I have attached a graph from our monitoring platform, and I have verified that the values are correct here.

How can I track down what is causing this unusually high load?

-Chris

Everyone's tags (1)
8 REPLIES
New Member

Re: Unusual CPU Usage on 3750G

Here is a show proc cpu. Adding up the columns show about 2-3% utilization total for 5 sec, and less than 2% for 1min and 5min. Why is it reporting 60%+? The interface is also slow to respond, so it feels like something actually is using 60%+ of the CPU.

CPU utilization for five seconds: 63%/0%; one minute: 64%; five minutes: 64%
 PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process 
   1         167      4262         39  0.00%  0.00%  0.00%   0 Chunk Manager    
   2       16807   1596737         10  0.00%  0.00%  0.00%   0 Load Meter       
   3           0         1          0  0.00%  0.00%  0.00%   0 CEF IPC Backgrou 
   4     6817713    860164       7926  0.00%  0.07%  0.05%   0 Check heaps      
   5           0        12          0  0.00%  0.00%  0.00%   0 Pool Manager     
   6           0         2          0  0.00%  0.00%  0.00%   0 Timers           
   7     3322358  17548192        189  0.00%  0.04%  0.03%   0 ARP Input        
   8           0         1          0  0.00%  0.00%  0.00%   0 AAA_SERVER_DEADT 
   9           0         2          0  0.00%  0.00%  0.00%   0 AAA high-capacit 
  10           0         1          0  0.00%  0.00%  0.00%   0 Policy Manager   
  11           8         5       1600  0.00%  0.00%  0.00%   0 Entity MIB API   
  12           0         1          0  0.00%  0.00%  0.00%   0 IFS Agent Manage 
  13         766    133714          5  0.00%  0.00%  0.00%   0 IPC Dynamic Cach 
  14           0         1          0  0.00%  0.00%  0.00%   0 IPC Zone Manager 
  15       60982   7779495          7  0.00%  0.00%  0.00%   0 IPC Periodic Tim 
  16       52566   7779495          6  0.00%  0.00%  0.00%   0 IPC Deferred Por 
  17        5914    533962         11  0.00%  0.00%  0.00%   0 IPC Seat Manager 
  18       27918   1990095         14  0.00%  0.00%  0.00%   0 HC Counter Timer 
  19           0         1          0  0.00%  0.00%  0.00%   0 HRPC asic-stats  
  20       71290   7779491          9  0.00%  0.00%  0.00%   0 Dynamic ARP Insp 
  21           0         1          0  0.00%  0.00%  0.00%   0 ARP Snoop        
  22           0         2          0  0.00%  0.00%  0.00%   0 XML Proxy Client 
  23           0         1          0  0.00%  0.00%  0.00%   0 Critical Bkgnd   
  24      227210   1275588        178  0.00%  0.01%  0.00%   0 Net Background   
  25          60      4171         14  0.00%  0.00%  0.00%   0 Logger           
  26       77339   7779452          9  0.00%  0.00%  0.00%   0 TTY Background   
  27      559430   7779496         71  0.15%  0.02%  0.00%   0 Per-Second Jobs  
  28     1568130    133719      11727  0.00%  0.00%  0.00%   0 Per-minute Jobs  
  29           0         2          0  0.00%  0.00%  0.00%   0 AggMgr Process   
  30          32      1035         30  0.00%  0.00%  0.00%   0 Net Input        
  31      123799   1594472         77  0.00%  0.00%  0.00%   0 Compute load avg 
  32         548      1842        297  0.00%  0.00%  0.00%   0 Collection proce 
  33       58141 132661708          0  0.00%  0.00%  0.00%   0 DownWhenLooped   
  34           0         1          0  0.00%  0.00%  0.00%   0 HRPC hdwl reques 
  35           0         1          0  0.00%  0.00%  0.00%   0 HRPC lpip reques 
  36           0         2          0  0.00%  0.00%  0.00%   0 HLPIP Sync Proce 
  37           0         1          0  0.00%  0.00%  0.00%   0 HRPC Multi-FS Sy 
  38           0        17          0  0.00%  0.00%  0.00%   0 HULC multifs pro 
  39           0         2          0  0.00%  0.00%  0.00%   0 MIRAGE RBCP Moni 
  40           0         1          0  0.00%  0.00%  0.00%   0 HRPC hsm request 
  41           0         7          0  0.00%  0.00%  0.00%   0 Stack Mgr        
  42         126         4      31500  0.00%  0.00%  0.00%   0 Stack Mgr Notifi 
  43     2605845 340914300          7  0.00%  0.12%  0.15%   0 Fifo Error Detec 
  44        5247       331      15851  0.00%  0.00%  0.00%   0 Adjust Regions   
  45      172595   7779461         22  0.00%  0.00%  0.00%   0 hrpc -> response 
  46           8       282         28  0.00%  0.00%  0.00%   0 hrpc -> request  
  47       26368   1594751         16  0.00%  0.00%  0.00%   0 hrpc <- response 
  48           0         3          0  0.00%  0.00%  0.00%   0 HULC Device Mana 
  49           0         3          0  0.00%  0.00%  0.00%   0 HRPC hdm non blo 
  50           0         3          0  0.00%  0.00%  0.00%   0 HRPC hdm blockin 
  51        7735   1594474          4  0.00%  0.00%  0.00%   0 HIPC bkgrd proce 
  52           8       180         44  0.00%  0.00%  0.00%   0 Hulc Port-Securi 
  53           0         1          0  0.00%  0.00%  0.00%   0 HRPC hpsecure re 
  54           0         1          0  0.00%  0.00%  0.00%   0 HRPC hlfm reques 
  55      325438 193767412          1  0.15%  0.01%  0.00%   0 HLFM address lea 
  56      146094   7779458         18  0.00%  0.00%  0.00%   0 HLFM aging proce 
  57      118087 193868147          0  0.00%  0.00%  0.00%   0 HLFM address ret 
  58           0         1          0  0.00%  0.00%  0.00%   0 HRPC hrcmd reque 
  59          44       529         83  0.00%  0.00%  0.00%   0 HRPC x_setup req 
  60           0         1          0  0.00%  0.00%  0.00%   0 HRPC system mtu  
  61       17441   2647583          6  0.00%  0.00%  0.00%   0 HVLAN main bkgrd 
  62           0         2          0  0.00%  0.00%  0.00%   0 HVLAN Mapped Vla 
  63           0         2          0  0.00%  0.00%  0.00%   0 Vlan shutdown Pr 
  64           0         1          0  0.00%  0.00%  0.00%   0 HRPC vlan reques 
  65           0         1          0  0.00%  0.00%  0.00%   0 HULC VLAN REF Ba 
  66           0         1          0  0.00%  0.00%  0.00%   0 HRPC hfbm reques 
  67         109     44601          2  0.00%  0.00%  0.00%   0 HCMP sync proces 
  68           0         1          0  0.00%  0.00%  0.00%   0 HRPC hulc misc r 
  69           0         1          0  0.00%  0.00%  0.00%   0 HPM Msg Retry Pr 
  70         323     66882          4  0.00%  0.00%  0.00%   0 DHCPD Timer      
  71         175        80       2187  0.00%  0.00%  0.00%   0 hpm main process 
  72           0       164          0  0.00%  0.00%  0.00%   0 HPM Stack Sync P 
  73           0         1          0  0.00%  0.00%  0.00%   0 HRPC pm request  
  74           0         3          0  0.00%  0.00%  0.00%   0 HPM if_num mappi 
  75     2854204   7779457        366  0.15%  0.13%  0.15%   0 hpm counter proc 
  76           0         1          0  0.00%  0.00%  0.00%   0 HRPC pm-counters 
  77           0         1          0  0.00%  0.00%  0.00%   0 hpm vp events ca 
  78           0         1          0  0.00%  0.00%  0.00%   0 HRPC hcmp reques 
  79          50      3816         13  0.00%  0.00%  0.00%   0 HCEF ADJ Refresh 
  80           0         5          0  0.00%  0.00%  0.00%   0 HL2MM            
  81           0         1          0  0.00%  0.00%  0.00%   0 HRPC hl2mm reque 
  82           0         1          0  0.00%  0.00%  0.00%   0 HRPC hl3mm reque 
  83           0         1          0  0.00%  0.00%  0.00%   0 hl3md_rpfq_thrl_ 
  84       26063   5500640          4  0.00%  0.00%  0.00%   0 hl3mm            
  85           0         1          0  0.00%  0.00%  0.00%   0 HACL Queue Proce 
  86           0         1          0  0.00%  0.00%  0.00%   0 HRPC acl request 
  87           9        57        157  0.00%  0.00%  0.00%   0 HACL Acl Manager 
  88           0         1          0  0.00%  0.00%  0.00%   0 HRPC backup inte 
  89       49854  14774307          3  0.00%  0.00%  0.00%   0 IP NAT Ager      
  90           0         1          0  0.00%  0.00%  0.00%   0 HRPC cdp request 
  91           0         1          0  0.00%  0.00%  0.00%   0 HRPC dot1x reque 
  92           0         4          0  0.00%  0.00%  0.00%   0 HULC DOT1X Proce 
  93           0         1          0  0.00%  0.00%  0.00%   0 HRPC sdm request 
  94      379100  38008349          9  0.00%  0.00%  0.00%   0 Hulc Storm Contr 
  95           0         2          0  0.00%  0.00%  0.00%   0 HSTP Sync Proces 
  96           0         1          0  0.00%  0.00%  0.00%   0 HRPC stp_cli req 
  97           0         1          0  0.00%  0.00%  0.00%   0 HRPC stp_state_s 
  98           0         2          0  0.00%  0.00%  0.00%   0 S/W Bridge Proce 
  99           0         1          0  0.00%  0.00%  0.00%   0 HRPC hudld reque 
 100           0         1          0  0.00%  0.00%  0.00%   0 HRPC vqpc reques 
 101           0         1          0  0.00%  0.00%  0.00%   0 HRPC iec_load_ba 
 102           0         1          0  0.00%  0.00%  0.00%   0 HRPC l2pt qnq rp 
 103        8837   3953766          2  0.00%  0.00%  0.00%   0 hl3mm_rp         
 104           0         1          0  0.00%  0.00%  0.00%   0 HRPC hled reques 
 105     6439762 157546603         40  0.15%  0.20%  0.19%   0 Hulc LED Process 
 106      881772   5762788        153  0.00%  0.01%  0.00%   0 HL3U bkgrd proce 
 107           0         1          0  0.00%  0.00%  0.00%   0 HRPC hl3u reques 
 108        8139   1822361          4  0.00%  0.00%  0.00%   0 HL3U PBR bkgrd p 
 109         578     66801          8  0.00%  0.00%  0.00%   0 HL3U PBR n-h res 
 110           0         1          0  0.00%  0.00%  0.00%   0 HRPC dtp request 
 111           0         1          0  0.00%  0.00%  0.00%   0 HRPC show_forwar 
 112           0         1          0  0.00%  0.00%  0.00%   0 HRPC snmp reques 
 113     2474011   1594489       1551  0.00%  0.07%  0.09%   0 HQM Stack Proces 
 114     2693258   3188974        844  0.15%  0.03%  0.00%   0 HRPC qos request 
 115           0         1          0  0.00%  0.00%  0.00%   0 HRPC span reques 
 116           0         1          0  0.00%  0.00%  0.00%   0 HRPC system post 
 117           0         1          0  0.00%  0.00%  0.00%   0 Hulc Reload Mana 
 118           0         1          0  0.00%  0.00%  0.00%   0 HRPC hrcli-event 
 119        4167   2267411          1  0.00%  0.00%  0.00%   0 DHCPD Database   
 120           8         2       4000  0.00%  0.00%  0.00%   0 image mgr        
 121           0         5          0  0.00%  0.00%  0.00%   0 HL2MCM           
 122           0         1          0  0.00%  0.00%  0.00%   0 HRPC hl2mcm mlds 
 123           0         2          0  0.00%  0.00%  0.00%   0 EAPoUDP Process  
 124           0         3          0  0.00%  0.00%  0.00%   0 CEF switching ba 
 125      444623   7779464         57  0.00%  0.01%  0.00%   0 PI MATM Aging Pr 
 126           0         1          0  0.00%  0.00%  0.00%   0 Switch Backup In 
 127         224    133712          1  0.00%  0.00%  0.00%   0 MMN bkgrd proces 
 128           0         2          0  0.00%  0.00%  0.00%   0 Dot1x Mgr Proces 
 129           0         1          0  0.00%  0.00%  0.00%   0 MAB Framework    
 130           0        37          0  0.00%  0.00%  0.00%   0 802.1x switch    
 131           0         1          0  0.00%  0.00%  0.00%   0 802.1x Critical  
 132       67744    598205        113  0.00%  0.00%  0.00%   0 DTP Protocol     
 133           0         1          0  0.00%  0.00%  0.00%   0 EAP Framework    
 134           0         1          0  0.00%  0.00%  0.00%   0 HRPC dai request 
 135           0         1          0  0.00%  0.00%  0.00%   0 HULC DAI Process 
 136           0         1          0  0.00%  0.00%  0.00%   0 HRPC dhcp snoopi 
 137           0         4          0  0.00%  0.00%  0.00%   0 HULC DHCP Snoopi 
 138           0         1          0  0.00%  0.00%  0.00%   0 HRPC ip source g 
 139           0         1          0  0.00%  0.00%  0.00%   0 HULC IP Source g 
 140       27992   8028032          3  0.00%  0.00%  0.00%   0 UDLD             
 141         670    267602          2  0.00%  0.00%  0.00%   0 Port-Security    
 142        8198    533961         15  0.00%  0.00%  0.00%   0 MDFS LC Download 
 143           0         2          0  0.00%  0.00%  0.00%   0 Switch IP Host T 
 144           0         1          0  0.00%  0.00%  0.00%   0 Link State Group 
 145        2447    800091          3  0.00%  0.00%  0.00%   0 Ethchnl          
 146          90      1032         87  0.00%  0.00%  0.00%   0 VMATM Callback   
 147           0         2          0  0.00%  0.00%  0.00%   0 AAA Server       
 148           0         1          0  0.00%  0.00%  0.00%   0 AAA ACCT Proc    
 149           0         1          0  0.00%  0.00%  0.00%   0 ACCT Periodic Pr 
 150      458670   1267410        361  0.00%  0.00%  0.00%   0 CDP Protocol     
 151           0         1          0  0.00%  0.00%  0.00%   0 TCP Command      
 152           0         1          0  0.00%  0.00%  0.00%   0 HRPC ilp request 
 153           0         2          0  0.00%  0.00%  0.00%   0 AAA Dictionary R 
 154         596     66903          8  0.00%  0.00%  0.00%   0 DHCP Snooping    
 155    23813059  71069427        335  0.95%  0.81%  0.75%   0 IP Input         
 156           0         1          0  0.00%  0.00%  0.00%   0 ICMP event handl 
 157      111128  70234353          1  0.00%  0.00%  0.00%   0 MDFS MFIB Proces 
 158     1152198   8022373        143  0.00%  0.01%  0.00%   0 Spanning Tree    
 159         318    133765          2  0.00%  0.00%  0.00%   0 Spanning Tree St 
 160           0         1          0  0.00%  0.00%  0.00%   0 CEF RF HULC Conv 
 161           0         3          0  0.00%  0.00%  0.00%   0 XDR mcast        
 162        3068    134122         22  0.00%  0.00%  0.00%   0 CEF background p 
 163           0         1          0  0.00%  0.00%  0.00%   0 IP IRDP          
 164           0         1          0  0.00%  0.00%  0.00%   0 IPC LC Message H 
 165           0         1          0  0.00%  0.00%  0.00%   0 XDR RP Ping Back 
 166         308     66882          4  0.00%  0.00%  0.00%   0 XDR RP backgroun 
 167           0         1          0  0.00%  0.00%  0.00%   0 XDR RP Test Back 
 168           0         3          0  0.00%  0.00%  0.00%   0 MDFS LC Process  
 169           0         1          0  0.00%  0.00%  0.00%   0 Routemap RP IPC  
 170         254    100317          2  0.00%  0.00%  0.00%   0 Cluster L2       
 171        7400    800089          9  0.00%  0.00%  0.00%   0 Cluster RARP     
 172       86247   1398019         61  0.00%  0.00%  0.00%   0 Cluster Base     
 173      575290   7401012         77  0.00%  0.02%  0.00%   0 TCP Timer        
 174      795848   2822113        282  0.00%  0.01%  0.00%   0 TCP Protocols    
 175           0         1          0  0.00%  0.00%  0.00%   0 Socket Timers    
 176          49     26765          1  0.00%  0.00%  0.00%   0 HTTP CORE        
 177           0         1          0  0.00%  0.00%  0.00%   0 RARP Input       
 178        1105       560       1973  0.00%  0.00%  0.00%   0 L2MM             
 179        3869     63652         60  0.00%  0.00%  0.00%   0 MRD              
 180      171135    757070        226  0.00%  0.00%  0.00%   0 IGMPSN           
 181           0         1          0  0.00%  0.00%  0.00%   0 IGMPQR           
 182           0         2          0  0.00%  0.00%  0.00%   0 L2TRACE SERVER   
 183          25       552         45  0.00%  0.00%  0.00%   0 MLDSN L2MCM      
 184           0         1          0  0.00%  0.00%  0.00%   0 MRD              
 185           0         1          0  0.00%  0.00%  0.00%   0 MLD_SNOOP        
 186          33         4       8250  0.00%  0.00%  0.00%   0 Crypto CA        
 187       17060    133766        127  0.00%  0.00%  0.00%   0 IP RIB Update    
 188           0         1          0  0.00%  0.00%  0.00%   0 Auth-proxy AAA B 
 189          77     26758          2  0.00%  0.00%  0.00%   0 IP Admin SM Proc 
 190        6643     30360        218  0.00%  0.00%  0.00%   0 DHCPD Receive    
 191           0         1          0  0.00%  0.00%  0.00%   0 Crypto PKI-CRL   
 192      192622  69704531          2  0.00%  0.00%  0.00%   0 MDFS RP process  
 193     3139516     16038     195754  0.00%  0.00%  0.00%   0 crypto sw pk pro 
 194           0         2          0  0.00%  0.00%  0.00%   0 AAA Cached Serve 
 195           0         2          0  0.00%  0.00%  0.00%   0 LOCAL AAA        
 196           0         2          0  0.00%  0.00%  0.00%   0 TPLUS            
 197           0         1          0  0.00%  0.00%  0.00%   0 Crypto SSL       
 198           0         9          0  0.00%  0.00%  0.00%   0 VTP Trap Process 
 199           0         2          0  0.00%  0.00%  0.00%   0 VTPMIB EDIT BUFF 
 200           0         2          0  0.00%  0.00%  0.00%   0 DHCP Security He 
 201           0         1          0  0.00%  0.00%  0.00%   0 HCD Process      
 202           0         1          0  0.00%  0.00%  0.00%   0 HRPC cable diagn 
 203           0         2          0  0.00%  0.00%  0.00%   0 DiagCard2/-1     
 204       99081  22078422          4  0.00%  0.00%  0.00%   0 PM Callback      
 205           8         4       2000  0.00%  0.00%  0.00%   0 VLAN Manager     
 206         721      4458        161  0.00%  0.00%  0.00%   0 SSH Event handle 
 207        2880    640421          4  0.00%  0.00%  0.00%   0 dhcp snooping sw 
 208           0         3          0  0.00%  0.00%  0.00%   0 RADIUS TEST CMD  
 209           0         2          0  0.00%  0.00%  0.00%   0 AAA SEND STOP EV 
 210           0         1          0  0.00%  0.00%  0.00%   0 Syslog Traps     
 211           0         2          0  0.00%  0.00%  0.00%   0 STP FAST TRANSIT 
 212           0         2          0  0.00%  0.00%  0.00%   0 CSRT RAPID TRANS 
 213      146968   1636298         89  0.00%  0.00%  0.00%   0 OSPF Hello       
 214     1181128  10068662        117  0.15%  0.01%  0.00%   0 CEF: IPv4 proces 
 215           9        62        145  0.00%  0.00%  0.00%   0 ADJ background   
 216       99400    133843        742  0.00%  0.00%  0.00%   0 IP Background    
 217        6667    999844          6  0.00%  0.00%  0.00%   0 Cluster Cmdr     
 218       71807   7896048          9  0.00%  0.00%  0.00%   0 OSPF Router 1    
 219          50        49       1020  0.00%  0.00%  0.00%   0 SpanTree Helper  
 220           0        39          0  0.00%  0.00%  0.00%   0 hulc cfg mgr mas 
 221           0         2          0  0.00%  0.00%  0.00%   0 CMDR VQP Proxy   
 222           0         4          0  0.00%  0.00%  0.00%   0 SNMP Timers      
 223           0         1          0  0.00%  0.00%  0.00%   0 reqRespRedirecti 
 224           0         5          0  0.00%  0.00%  0.00%   0 CommStringConfig 
 225      819319   2833330        289  0.00%  0.00%  0.00%   0 IP SNMP          
 226      168839   1424517        118  0.00%  0.00%  0.00%   0 PDU DISPATCHER   
 227      770231   1424776        540  0.00%  0.00%  0.00%   0 SNMP ENGINE      
 228           0         1          0  0.00%  0.00%  0.00%   0 SNMP ConfCopyPro 
 229           0         2          0  0.00%  0.00%  0.00%   0 SNMP Traps       
 230           0         1          0  0.00%  0.00%  0.00%   0 VQP client recei 
 231           0         1          0  0.00%  0.00%  0.00%   0 VQP general      
 232       30922       172     179779  0.00%  0.05%  0.15%   0 hulc running con 
 233        1064         9     118222  0.00%  0.00%  0.00%   2 SSH Process      
 235        1065        15      71000  0.00%  0.00%  0.00%   4 SSH Process      
 236        1954       667       2929  0.31%  0.14%  0.17%   5 SSH Process

Cisco Employee

Re: Unusual CPU Usage on 3750G

Hello,

This is a document that may be of interest to you:

http://www.cisco.com/en/US/products/hw/switches/ps5023/products_tech_note09186a00807213f5.shtml

Can you also have a look at the show processes cpu sorted output? Your output is currently sorted according to the PID, not according to the total load. Your current output suggests that the CPU load is caused by a process consuming many resources. The processes should be identifiable in the sorted output. It may help you to narrow down the search (for example, excessive BPDUs received, lots of IGMP traffic, perhaps a routing protocol issue).

Alternatively, try the show processes cpu sorted 1min and show processes cpu sorted 5min commands to see the output sorted according to longer-period loads.

Best regards,

Peter

New Member

Re: Unusual CPU Usage on 3750G

This is what doesn't make sense... if you add up the total CPU usage reported, it's less than 3%... but it's still showing 60%, and it does "feel" like something is slowing this device way down by the way it's responding to pings directly and SSH delay when typing. See below:

#show proc cpu sorted 5sec
CPU utilization for five seconds: 63%/0%; one minute: 66%; five minutes: 65%
 PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process 
 155    23862737  71198161        335  0.78%  0.75%  0.79%   0 IP Input         
 236        1140       256       4453  0.31%  1.36%  0.33%   5 SSH Process      
 105     6453039 157621546         40  0.15%  0.24%  0.21%   0 Hulc LED Process 
  43     2615320 341049414          7  0.15%  0.16%  0.15%   0 Fifo Error Detec 
  57      118440 193952074          0  0.15%  0.01%  0.00%   0 HLFM address ret 
  75     2864311   7785216        367  0.15%  0.15%  0.15%   0 hpm counter proc 
   6           0         2          0  0.00%  0.00%  0.00%   0 Timers           
   5           0        12          0  0.00%  0.00%  0.00%   0 Pool Manager     
   7     3325428  17560695        189  0.00%  0.06%  0.04%   0 ARP Input        
   4     6823244    860848       7926  0.00%  0.07%  0.05%   0 Check heaps      
  11           8         5       1600  0.00%  0.00%  0.00%   0 Entity MIB API   
   8           0         1          0  0.00%  0.00%  0.00%   0 AAA_SERVER_DEADT 
   9           0         2          0  0.00%  0.00%  0.00%   0 AAA high-capacit 
  14           0         1          0  0.00%  0.00%  0.00%   0 IPC Zone Manager 
  10           0         1          0  0.00%  0.00%  0.00%   0 Policy Manager   
  16       52647   7785263          6  0.00%  0.00%  0.00%   0 IPC Deferred Por 
******** ITEMS BELOW HERE ARE ALL 0.00% ********
Cisco Employee

Re: Unusual CPU Usage on 3750G

Hello,

Do the 1min and 5min sorted results provide similar output?

Try to also have a look on the show platform tcam utilization output to see whether any of the TCAM applications is maxing out the allotted TCAM place (compare the Max Masks/Values column to the Used Masks/values and see whether any usage is close to the max value).

Have you had a look on the URL I referenced in my first reply? There is a number of possible scenarios responsible for high CPU load. Is any of those scenarios improbable for your situation?

Best regards,

Peter

New Member

Re: Unusual CPU Usage on 3750G

Sorting by 1min and 5min on the CPU utilization shows simliar results -- all totals are less than 3%, yet it's showing 60%+ utilization.

Also, on TCAM all looks good:

#show platform tcam utilization 

CAM Utilization for ASIC# 0                      Max            Used
                                             Masks/Values    Masks/values

 Unicast mac addresses:                        784/6272         54/373   
 IPv4 IGMP groups + multicast routes:          144/1152          7/29    
 IPv4 unicast directly-connected routes:       784/6272         54/373   
 IPv4 unicast indirectly-connected routes:     272/2176         24/133   
 IPv4 policy based routing aces:                 0/0             0/0     
 IPv4 qos aces:                                512/512           6/6     
 IPv4 security aces:                          1024/1024         23/23    

Note: Allocation of TCAM entries per feature uses
a complex algorithm. The above information is meant
to provide an abstract view of the current TCAM utilization

I'm reviewing the document you linked to now. Will post followup on that shortly.

New Member

Re: Unusual CPU Usage on 3750G

I reviewed the document you posted, and the only thing that seems like it might apply is the excessive ARP problem mentioned. Looking at the ARP table, there are 401 entries, and 80 of them are Incomplete.

I put a packet sniffer on the largest VLAN segment, and I'm seeing ARP requests going by about 4-6 per second. That seems like a lot, but there are probably 100 hosts on that particular network segment, so maybe not. Most of them are not broadcast.

-Chris

Cisco Employee

Re: Unusual CPU Usage on 3750G

Hello Chris,

Having 4-6 ARP packets per second on a large network should not be causing such a high load on your CPU.

I would like to ask you: is it possible for you to perform a reload of your 3750 switch? Your IOS is quite dated and it is possible that there are some software issues. If the CPU load decreases significantly after the reload then there is probably something going on in your IOS (which you probably should upgrade so or so).

Also, is it certain that there is no Layer2 loop in your network? Frequently, looping BPDUs, IP broadcasts and similar issues can result in increased CPU load. The show controllers utilization command could help you to pinpoint an interface with heightened load which would be indicative of, among other things, a possible Layer2 loop. The show ip traffic command is also very helpful in determining whether the CPU is loaded with inappropriate number of IP packets requiring special handling.

Best regards,

Peter

New Member

Re: Unusual CPU Usage on 3750G

Well, the CPU load just kept creeping up. It hit 90% sustained, so I started shutting ports down. The problem didn't go away until I shutdown a VLAN that is the largest segment of the network (spans 5 ports, about 75 end-point devices). Not big by any means, but as soon as I shutdown that VLAN the CPU load dropped to 5%. I then brought everything (including that VLAN) back up, and it's sustained at 5% now.

I think there is a STP problem going on here. I have checked the network for physical network loops, and there are none.

There are a total of 5 switches on this network segment that would participate in STP. I'm going to pull out my trusty CCNA/CCNP books and brush up on STP. I haven't configured -- or even thought about -- STP in at least a couple of years. It usually just works.

I'll post what I finally do to resolve this.

-Chris

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