[c-nsp] RE: Unknown reason for High CPU 3620

Temkin, David temkin at sig.com
Fri Nov 5 08:42:39 EST 2004


3620 can do 2,000pps process switched and 20,000-40,000 in CEF depending
on the alignment of the stars.



> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net 
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of 
> Jack.W.Parks at alltel.com
> Sent: Friday, November 05, 2004 8:32 AM
> To: afoster at gammatelecom.com; rodunn at cisco.com
> Cc: cisco-nsp at puck.nether.net
> Subject: RE: [c-nsp] RE: Unknown reason for High CPU 3620
> 
> To be honest, I think the box is maxed out from a PPS 
> perspective.  You are sending 2,000 pps each direction and I 
> bet that all the packets are process switched.  The 20-40 
> kpps numbers are for CEF switching only. Obviously, Cisco 
> would not sell many routers if they used non-CEF forwarding 
> statistics in their documentation.
>  
> You should be able to look at the "show interface switching" 
> output to see if your process switching the packets.  ATM SAR 
> function should be handled by the ATM interface itself and 
> NOT by the processor. The SAR function is not contributing to 
> the CPU utilization.  Since you are bridging, you are process 
> switching and you are getting 2 kpps which is the maximum 
> process switched performance you can expect.
>  
> Check out this link.  Scoll down to "Platform performance comparison"
>  
> http://www.cisco.com/en/US/partner/products/hw/routers/ps5199/
> prod_bulletin09186a008032d40e.html
>  
> I'm sure their are more stats about each platform, it just 
> takes some digging around CCO.
>  
> Jack
>  
> 
> 	-----Original Message----- 
> 	From: cisco-nsp-bounces at puck.nether.net on behalf of 
> Alex Foster 
> 	Sent: Fri 11/5/2004 5:26 AM 
> 	To: Rodney Dunn 
> 	Cc: cisco-nsp at puck.nether.net 
> 	Subject: RE: [c-nsp] RE: Unknown reason for High CPU 3620
> 	
> 	
> 
> 
> 	The Reasons for bridging are explained in the diagram below.
> 	
> 	                 Bridging                 Bridging
> 	Firewall ---- eth |7206| atm --------- atm |3620| eth ----- ISP
> 	
> 	So essentially I am using the ATM network to extend the 
> connection from
> 	the ISP to our Firewall. In this situation you can see 
> why I cant route.
> 	I cant see how L2TP will be of any help here - comments 
> or suggestions
> 	are very welcome - Also the ATM network does not 
> support MPLS (fairly
> 	old OS on our ATM switches).
> 	
> 	Thanks Again
> 	
> 	Alex
> 	
> 	
> 	-----Original Message-----
> 	From: Rodney Dunn [mailto:rodunn at cisco.com]
> 	Sent: 04 November 2004 15:42
> 	To: Alex Foster
> 	Cc: cisco-nsp at puck.nether.net
> 	Subject: Re: [c-nsp] RE: Unknown reason for High CPU 3620
> 	
> 	On Wed, Nov 03, 2004 at 11:46:09PM -0000, Alex Foster wrote:
> 	> Hi
> 	>
> 	> The LANE configuration is used for management only - 
> occassional snmp
> 	> queries etc; so the bulk of traffic is being bridged 
> between e1/0 and
> 	atm
> 	> 0/0.2.  Are you saying therefore that bridging is far 
> more intensive
> 	than
> 	> routing/switching at interrupt level? Why is that 
> (sorry for the
> 	question -
> 	> just curious).
> 	
> 	Yes that's correct.  Old code and was never designed 
> for high speed
> 	switching.
> 	
> 	>
> 	> The load on this connection will soon increase to a 
> constant 40 - 60
> 	Mbps
> 	> (again bridging - cant route unfortunately).  
> Obviously the 3620 wont
> 	handle
> 	> this - I have a 7206 (NPE-400) available, would this 
> box suffice for
> 	the
> 	> traffic load I am estimating - I can upgrade the 7206 to a G1
> 	processor if
> 	> needs be.
> 	
> 	It would have to be tested in the lab to know for sure. 
>  It's all
> 	about processor speed and feature excecution on a per 
> packet basis.
> 	The old transparent bridging code isn't a great performer even
> 	though it's still under interrupt level.  It's a 
> totally different
> 	code path than raw packet switching.
> 	
> 	Someone else mentioned other types of L2 bridging (ATOM/L2TPv3).
> 	Those are new technologies designed to carry L2 frames over
> 	a L3 transport.
> 	
> 	It's hard to say what your best solution would be 
> without understanding
> 	the overall environement you have.  ie: Why are you 
> bridging in the
> 	first place?
> 	
> 	
> 	>
> 	> Thanks for your time
> 	>
> 	> Alex
> 	>
> 	> -----Original Message-----
> 	> From: Rodney Dunn [mailto:rodunn at cisco.com]
> 	> Sent: 03 November 2004 17:40
> 	> To: Alex Foster
> 	> Cc: Rodney Dunn; cisco-nsp at puck.nether.net
> 	> Subject: Re: [c-nsp] RE: Unknown reason for High CPU 3620
> 	>
> 	>
> 	> Bridging with LANE at that rate.  My guess is
> 	> that would probably be normal on a 3620.
> 	>
> 	> Your option would be to get a faster processor
> 	> or stop bridging.
> 	>
> 	> To be 100% sure it would need to be set up in the
> 	> lab with a packet generator under a controlled
> 	> test.
> 	>
> 	> Your sh int stat confirms at least the most of the
> 	> traffic is being handled under interrupt level which
> 	> is good.
> 	>
> 	>
> 	> Rodney
> 	>
> 	> On Wed, Nov 03, 2004 at 05:19:54PM -0000, Alex Foster wrote:
> 	> > Thanks Rodney - find config attached - the collisions were
> 	historical -
> 	> > the interface is running full-duplex - here is the 
> current interface
> 	> > stats - the input errors are being investigated - 
> but shouldn't be
> 	> > responsible for the high CPU. Have also included sh 
> vers and sh int
> 	> > stat.
> 	> >
> 	> > #sh int e1/0
> 	> > Ethernet1/0 is up, line protocol is up
> 	> >   Hardware is AmdP2, address is 0005.3245.e070 (bia 
> 0005.3245.e070)
> 	> >   Description:
> 	> >   MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
> 	> >      reliability 255/255, txload 39/255, rxload 39/255
> 	> >   Encapsulation ARPA, loopback not set
> 	> >   Keepalive set (10 sec)
> 	> >   ARP type: ARPA, ARP Timeout 04:00:00
> 	> >   Last input 00:00:00, output 00:00:00, output hang never
> 	> >   Last clearing of "show interface" counters 03:03:41
> 	> >   Queueing strategy: fifo
> 	> >   Output queue 0/40, 0 drops; input queue 1/75, 790 drops
> 	> >   5 minute input rate 1531000 bits/sec, 1935 packets/sec
> 	> >   5 minute output rate 1532000 bits/sec, 2170 packets/sec
> 	> >      21533985 packets input, 2108844947 bytes, 0 no buffer
> 	> >      Received 62660 broadcasts, 0 runts, 0 giants, 
> 0 throttles
> 	> >      130659 input errors, 1608 CRC, 1272 frame, 0 
> overrun, 129051
> 	> > ignored
> 	> >      0 input packets with dribble condition detected
> 	> >      23817320 packets output, 2045363543 bytes, 0 
> underruns(0/0/0)
> 	> >      0 output errors, 0 collisions, 0 interface resets
> 	> >      0 babbles, 0 late collision, 0 deferred
> 	> >      0 lost carrier, 0 no carrier
> 	> >      0 output buffer failures, 0 output buffers swapped out
> 	> >
> 	> > #sh vers
> 	> > Cisco Internetwork Operating System Software
> 	> > IOS (tm) 3600 Software (C3620-IS-M), Version 
> 12.2(3), RELEASE
> 	SOFTWARE
> 	> > (fc1)
> 	> > Copyright (c) 1986-2001 by cisco Systems, Inc.
> 	> > Compiled Wed 18-Jul-01 13:45 by pwade
> 	> > Image text-base: 0x600089A8, data-base: 0x6116A000
> 	> >
> 	> > ROM: System Bootstrap, Version 11.1(20)AA2, EARLY 
> DEPLOYMENT RELEASE
> 	> > SOFTWARE (fc1)
> 	> >
> 	> > xxxxxxxx uptime is 1 year, 29 weeks, 5 days, 1 
> hour, 48 minutes
> 	> > System returned to ROM by power-on
> 	> > System image file is "flash:c3620-is-mz.122-3.bin"
> 	> >
> 	> > cisco 3620 (R4700) processor (revision 0x81) with 
> 41984K/7168K bytes
> 	of
> 	> > memory.
> 	> > Processor board ID 25121827
> 	> > R4700 CPU at 80Mhz, Implementation 33, Rev 1.0
> 	> > Bridging software.
> 	> > X.25 software, Version 3.0.0.
> 	> > SuperLAT software (copyright 1990 by Meridian 
> Technology Corp).
> 	> > 4 Ethernet/IEEE 802.3 interface(s)
> 	> > 1 ATM network interface(s)
> 	> > DRAM configuration is 32 bits wide with parity disabled.
> 	> > 29K bytes of non-volatile configuration memory.
> 	> > 16384K bytes of processor board System flash (Read/Write)
> 	> >
> 	> > Configuration register is 0x2102
> 	> >
> 	> >
> 	> > #sh int stat
> 	> > ATM0/0
> 	> >           Switching path    Pkts In   Chars In   
> Pkts Out  Chars Out
> 	> >                Processor      60671    5098714     
> 161118   15856770
> 	> >              Route cache   25347153 2543070267   
> 22778769 2540265463
> 	> >                    Total   25407824 2548168981   
> 22939887 2556122233
> 	> > Ethernet1/0
> 	> >           Switching path    Pkts In   Chars In   
> Pkts Out  Chars Out
> 	> >                Processor      43533    2674126      
>  7176     430560
> 	> >              Route cache   22903843 2234233191   
> 25355781 2188907917
> 	> >                    Total   22947376 2236907317   
> 25362957 2189338477
> 	> > Interface Ethernet1/1 is disabled
> 	> >
> 	> > Interface Ethernet1/2 is disabled
> 	> >
> 	> > Interface Ethernet1/3 is disabled
> 	> >
> 	> > Building configuration...
> 	> >
> 	> > Current configuration : 1868 bytes
> 	> > !
> 	> > version 12.2
> 	> > service timestamps debug uptime
> 	> > service timestamps log uptime
> 	> > service password-encryption
> 	> > !
> 	> > hostname xxxxxxxxxx
> 	> > !
> 	> > logging buffered 4096 debugging
> 	> > enable secret
> 	> > !
> 	> > ip subnet-zero
> 	> > !
> 	> > !
> 	> > no ip domain-lookup
> 	> > !
> 	> > call rsvp-sync
> 	> > !
> 	> > bridge crb
> 	> > !
> 	> > interface ATM0/0
> 	> >  no ip address
> 	> >  atm uni-version 3.1
> 	> >  no atm ilmi-keepalive
> 	> >  pvc 0/5 qsaal
> 	> >  !
> 	> >  pvc 0/16 ilmi
> 	> >  !
> 	> > !
> 	> > interface ATM0/0.1 multipoint
> 	> >  ip address xxxxxxx
> 	> >  lane server-atm-address 
> C5.777777777777777777777777.777777777777.77
> 	> >  lane client ethernet xxxxxxx
> 	> >  no cdp enable
> 	> > !
> 	> > interface ATM0/0.2 multipoint
> 	> >  pvc 0/103
> 	> >   encapsulation aal5snap
> 	> >  !
> 	> >  bridge-group 1
> 	> > !
> 	> > interface Ethernet1/0
> 	> >  description
> 	> >  no ip address
> 	> >  no ip mroute-cache
> 	> >  full-duplex
> 	> >  no cdp enable
> 	> >  bridge-group 1
> 	> > !
> 	> > no ip http server
> 	> > !
> 	> > no cdp run
> 	> > !
> 	> > bridge 1 protocol ieee
> 	> > !
> 	> > dial-peer cor custom
> 	> > !
> 	> > !
> 	> >
> 	> > -----Original Message-----
> 	> > From: Rodney Dunn [mailto:rodunn at cisco.com]
> 	> > Sent: 03 November 2004 16:08
> 	> > To: Alex Foster
> 	> > Cc: cisco-nsp at puck.nether.net
> 	> > Subject: Re: [c-nsp] RE: Unknown reason for High CPU 3620
> 	> >
> 	> > CPU load at interrupt level is almost always packet
> 	> > switching/features or alignment/spurious access corrections.
> 	> >
> 	> > This CPU sounds high for that amount of traffic.
> 	> >
> 	> > Can you list the full configuration /*taking out
> 	> > any confidential stuff*/ so we can see the features
> 	> > enabled?
> 	> >
> 	> > 2nd, you really need to clean up that ethernet
> 	> > segement with all the collisions.  Can you convert
> 	> > it to full-duplex?  I don't recall if you can do it
> 	> > with the 3620 in later code.
> 	> >
> 	> > Most likely it's not an issue with the ATM side.
> 	> >
> 	> > Rodney
> 	> >
> 	> >
> 	> > On Wed, Nov 03, 2004 at 03:44:07PM -0000, Alex Foster wrote:
> 	> > > Thanks to the guys who responded - I have managed 
> to narrow down
> 	the
> 	> > > cause to high interrupt utilization and not 
> processor utilization
> 	-
> 	> > but
> 	> > > Im still a little unclear as to what is causing 
> the high interrupt
> 	> > util.
> 	> > > - is the ATM interface causing this ?  Again the 
> traffic load is
> 	> > little
> 	> > > over 1.5 meg (in/out) - but constant - so I am 
> wondering if the
> 	> > > continual SARing is maybe having a negative 
> effect on the CPU ?
> 	If so
> 	> > -
> 	> > > is there a workaround or am I looking at a bigger 
> platform to
> 	solve
> 	> > the
> 	> > > issue - if so any recommendations (I have a 3640 
> available but
> 	don't
> 	> > > know if this will provide much of an improvement).
> 	> > >
> 	> > >
> 	> > >
> 	> > > Regards
> 	> > >
> 	> > >
> 	> > >
> 	> > > Alex
> 	> > >
> 	> > >
> 	> > >
> 	> > >
> 	> > >
> 	> > > -----Original Message-----
> 	> > > From: Alex Foster
> 	> > > Sent: 03 November 2004 13:37
> 	> > > To: 'cisco-nsp at puck.nether.net'
> 	> > > Subject: Unknown reason for High CPU 3620
> 	> > >
> 	> > >
> 	> > >
> 	> > > I have a 3620 that is currently maxing out its 
> CPU for no apparent
> 	> > > reason - the traffic load on it at the moment is 
> about 1 to 2 meg
> 	-
> 	> > and
> 	> > > sh proc cpu doesn't indicate any process that is 
> causing the high
> 	CPU
> 	> > > util.  Most of the traffic is SIP but I wouldn't 
> have thought this
> 	> > would
> 	> > > have any bearing.  There are only two interfaces 
> on the box in use
> 	-
> 	> > an
> 	> > > ATM 155 and a 10bt.  The traffic from the 10bt is 
> bridged to a PVC
> 	on
> 	> > > the ATM interface - nothing complicated.
> 	> > >
> 	> > >
> 	> > >
> 	> > > #sh proc cpu
> 	> > >
> 	> > > CPU utilization for five seconds: 96%/93%; one 
> minute: 90%; five
> 	> > > minutes: 91%
> 	> > >
> 	> > >  PID Runtime(ms)   Invoked      uSecs   5Sec   
> 1Min   5Min TTY
> 	Process
> 	> > >
> 	> > >    1      194708       9899756         19    
> 0.00%  0.00%  0.00%
> 	0
> 	> > > Load Meter
> 	> > >
> 	> > >    2        2008          223                9004 
>  1.41%  0.13%
> 	0.03%
> 	> > > 66 Virtual Exec
> 	> > >
> 	> > >
> 	> > >
> 	> > > #sh mem sum
> 	> > >
> 	> > >                 Head    Total(b)     Used(b)     Free(b)
> 	Lowest(b)
> 	> > > Largest(b)
> 	> > >
> 	> > > Processor   61D70EA0    12120416     6616992     5503424
> 	5303744
> 	> > > 5305428
> 	> > >
> 	> > >       I/O    2900000     7340032     4387068     2952964
> 	2920520
> 	> > > 2947260
> 	> > >
> 	> > >
> 	> > >
> 	> > > #sh int e1/0
> 	> > >
> 	> > > Ethernet1/0 is up, line protocol is up
> 	> > >
> 	> > >   Hardware is AmdP2, address is 0005.3245.e070 (bia
> 	0005.3245.e070)
> 	> > >
> 	> > >   Description:
> 	> > >
> 	> > >   MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
> 	> > >
> 	> > >      reliability 255/255, txload 34/255, rxload 37/255
> 	> > >
> 	> > >   Encapsulation ARPA, loopback not set
> 	> > >
> 	> > >   Keepalive set (10 sec)
> 	> > >
> 	> > >   ARP type: ARPA, ARP Timeout 04:00:00
> 	> > >
> 	> > >   Last input 00:00:00, output 00:00:00, output hang never
> 	> > >
> 	> > >   Last clearing of "show interface" counters 1y4w
> 	> > >
> 	> > >   Queueing strategy: fifo
> 	> > >
> 	> > >   Output queue 0/40, 0 drops; input queue 0/75, 
> 103522 drops
> 	> > >
> 	> > >   5 minute input rate 1470000 bits/sec, 1984 packets/sec
> 	> > >
> 	> > >   5 minute output rate 1355000 bits/sec, 2166 packets/sec
> 	> > >
> 	> > >      2150894411 packets input, 1646909945 bytes, 
> 0 no buffer
> 	> > >
> 	> > >      Received 88151770 broadcasts, 0 runts, 0 
> giants, 0 throttles
> 	> > >
> 	> > >      6397644 input errors, 42166 CRC, 32878 
> frame, 0 overrun,
> 	6355422
> 	> > > ignored
> 	> > >
> 	> > >      0 input packets with dribble condition detected
> 	> > >
> 	> > >      2681876495 packets output, 1769855380 bytes, 0
> 	> > > underruns(556991/1663306/0)
> 	> > >
> 	> > >      165 output errors, 2220297 collisions, 50 
> interface resets
> 	> > >
> 	> > >      0 babbles, 47 late collision, 1067254 deferred
> 	> > >
> 	> > >      118 lost carrier, 0 no carrier
> 	> > >
> 	> > >      0 output buffer failures, 0 output buffers 
> swapped out
> 	> > >
> 	> > >
> 	> > >
> 	> > > #sh int atm 0/0.2
> 	> > >
> 	> > > ATM0/0.2 is up, line protocol is up
> 	> > >
> 	> > >   Hardware is RS8234 ATMOC3
> 	> > >
> 	> > >   MTU 4470 bytes, BW 155000 Kbit, DLY 80 usec,
> 	> > >
> 	> > >      reliability 255/255, txload 2/255, rxload 2/255
> 	> > >
> 	> > >   Encapsulation ATM
> 	> > >
> 	> > >   3075506957 packets input, 1094442885139 bytes
> 	> > >
> 	> > >   2362546968 packets output,988686523562 bytes
> 	> > >
> 	> > >   0 OAM cells input, 0 OAM cells output
> 	> > >
> 	> > >   AAL5 CRC errors : 81
> 	> > >
> 	> > >   AAL5 SAR Timeouts : 0
> 	> > >
> 	> > >   AAL5 Oversized SDUs : 0
> 	> > >
> 	> > >   AAL5 length violation : 26
> 	> > >
> 	> > >   AAL5 CPI Error : 0
> 	> > >
> 	> > >
> 	> > >
> 	> > > Thanks
> 	> > >
> 	> > >
> 	> > >
> 	> > > Alex
> 	> > >
> 	> > >
> 	> > >
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