[c-nsp] low throughput of 10GbE line

Jirí Procházka jiri.prochazka at superhosting.cz
Mon Mar 15 12:26:50 EDT 2010


Hello,

I'm totally stucked with the following problem ->

Catalyst 7606 ( IOS 12.2(33)SRD4) with WS-F6700-DFC3CXL module connected 
with C3750-E (IOS 12.2(40)SE) over TenGigabit Xenpaks. Its one of our 
backbone lines, transferring only VLAN-201.

There are two small subnets in this VLAN assigned to two servers, which are 
connected to 3750. Vlan-201 is routed on 7606

When traffic on this link reaches aproximately 6Gbps, latence to servers 
gets rapidly worse (about 100-150ms, about 2ms before) and speed is 
unpredictably slowing. Servers are able to generate much more than 10Gbps. I 
have tried to assign IP from this VLAN directly to vlan-interface at 3750 
and latence is bad as well.


The two problems which I can see at 7606 are following:

1) Input queue drops at the interface. They appear at the same time as the 
high latence. I tried to set lower hold-queue, but no difference. Any type 
of qos or other bandwidht limiting methods are applied.

sitel-edge-new#show int te4/8
TenGigabitEthernet4/8 is up, line protocol is up (connected)
  Hardware is C7600 10Gb 802.3, address is 001e.f7f7.bd5f (bia 
001e.f7f7.bd5f)
  Description: SITEL-TTC-New10GbE
  MTU 1500 bytes, BW 10000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 3/255, rxload 126/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 10Gb/s
  Transport mode LAN (10GBASE-R, 10.3125Gb/s)
  input flow-control is off, output flow-control is off
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:07, output 00:00:41, output hang never
  Last clearing of "show interface" counters 18:56:25
  Input queue: 0/4096/96151289/0 (size/max/drops/flushes); Total output 
drops: 0
  Queueing strategy: fifo
  Output queue: 0/4096 (size/max)
  30 second input rate 4942942000 bits/sec, 410813 packets/sec
  30 second output rate 143433000 bits/sec, 241176 packets/sec
     34434311308 packets input, 51018973201607 bytes, 0 no buffer
     Received 21472 broadcasts (17607 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 96151289 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     19623750753 packets output, 3094225873410 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out


the second side of line looks ok

TTC-3750-MAIN#show int te2/0/2
TenGigabitEthernet2/0/2 is up, line protocol is up (connected)
  Hardware is Ten Gigabit Ethernet, address is 001e.7a4f.fb9e (bia 
001e.7a4f.fb9e)
  Description: TTC-SITEL-New10GbE
  MTU 1600 bytes, BW 10000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 129/255, rxload 3/255
  Encapsulation ARPA, loopback not set
  Keepalive not set
  Full-duplex, 10Gb/s, link type is auto, media type is 10GBase-SR
  Media-type configured as  connector
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:51, output 00:00:16, output hang never
  Last clearing of "show interface" counters 01:36:19
  Input queue: 0/4096/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/4096 (size/max)
  30 second input rate 149330000 bits/sec, 249506 packets/sec
  30 second output rate 5062720000 bits/sec, 420886 packets/sec
     1400794396 packets input, 104446053346 bytes, 0 no buffer
     Received 0 broadcasts (1250 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 1250 multicast, 0 pause input
     0 input packets with dribble condition detected
     2427526833 packets output, 3649915537744 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 PAUSE output
     0 output buffer failures, 0 output buffers swapped out




2) It looks that concerned transciever is a little bit overheated..but I 
don't trust these sensors much..

sitel-edge-new#show interfaces transceiver
Transceiver monitoring is disabled for all interfaces.

                                           Optical   Optical
           Temperature  Voltage  Current   Tx Power  Rx Power
Port       (Celsius)    (Volts)  (mA)      (dBm)     (dBm)
---------  -----------  -------  --------  --------  --------
Te4/1        39.3       0.00      36.8      -2.8      -1.0
Te4/2        34.6       0.00      43.1      -2.6      -3.3
Te4/3        36.8       0.00      29.7      -2.5      -1.0
Te4/4        35.3       0.00       5.9      -1.9      -1.7
Te4/5        44.1       0.00      45.4      -2.0      -7.7
Te4/6        40.0       0.00      36.0      -3.4      -2.2
Te4/7        40.8       0.00      34.0      -3.3      -0.5 +
Te4/8        71.9 +     0.00       6.0      -3.2      -3.4




some more debug info:

7606 ->

sitel-edge-new#show platform hardware capacity fabric
Switch Fabric Resources
  Bus utilization: current: 35%, peak was 47% at 19:53:03 CET Thu Mar 11 
2010
  Fabric utilization:     Ingress                    Egress
    Module  Chanl  Speed  rate  peak                 rate  peak
    1       0        20G   14%   21% @18:26 11Mar10   19%   31% @18:20 
12Mar10
    2       0        20G   25%   39% @17:50 11Mar10    2%   10% @02:07 
12Mar10
    2       1        20G   10%   26% @19:41 11Mar10   33%   49% @18:06 
11Mar10
    4       0        20G   25%   63% @13:00 14Mar10    5%   20% @18:15 
11Mar10
    4       1        20G   45%   79% @18:07 11Mar10   50%   73% @09:43 
13Mar10
    5       0        20G    2%    5% @14:22 12Mar10   12%   19% @19:08 
11Mar10
  Switching mode: Module                                        Switching 
mode
                  1 
truncated
                  2 
truncated
                  4 
compact
                  5                                               flow 
through




I'm going to replace the "overheated" transciever in 7606 this night and 
hope it's the solution..but don't trust it much.


Any advice would be really appreciated!


Best regards,


Jiri Prochazka 



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