[asterisk-ss7] MTP2 CRC errors resulting in flapping link

[Kai Militzer]

Hi,

Paul Cadach wrote:
> You mix CRC4 (which is used to check CAS signalling/framing consistency) and
> CRC16/CRC32 (which is used to check HDLC frame consistency).

> Looks like interrupt/CPU load is high which causes raw time slot data looses.

The assumption with a lot of interrupts causing this problem seems to be 
right. See the following output of vmstat (the first is the system with 
the problems, the second a system without the problem (also running 
chan_ss7)). On the system with the problem there is a mass of interrupts.

ss7-gate1:~# vmstat -n 1
procs -----------memory---------- ---swap-- -----io---- --system-- 
----cpu----
  r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us 
sy id wa
  0  0      0   9260  82860 862476    0    0     2     2    3     4  0 
1 98  0
  0  0      0   9260  82860 862476    0    0     0     0 2014     0  0 
0 100  0
  1  1      0   9260  82868 862468    0    0     0    80 2169     0  0 
1 99  0
  0  0      0   9260  82868 862468    0    0     0     0 2019     0  0 
0 100  0
  0  0      0   9260  82868 862468    0    0     0    48 2104     0  0 
1 99  0
  0  0      0   9260  82868 862468    0    0     0     0 2009     0  3 
5 92  0
  0  0      0   9260  82868 862468    0    0     0     0 2006     0  0 
7 93  0
  0  0      0   9260  82868 862468    0    0     0   236 2481     0  2 
3 95  0
  0  0      0   9260  82868 862468    0    0     0     0 2007     0  0 
0 100  0
  0  0      0   9196  82868 862468    0    0     0    60 2129     0  0 
0 98  1
  0  0      0   9196  82868 862468    0    0     0     0 2007     0  0 
0 100  0


ss7-gate2:~# vmstat -n 1
procs -----------memory---------- ---swap-- -----io---- --system-- 
----cpu----
  r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us 
sy id wa
  4  0      0   5572  54844 142156    0    0     9     8   10    10  3 
8 89  0
  0  0      0   5572  54844 142156    0    0     0     0    0     0  1 
1 98  0
  0  0      0   5572  54844 142156    0    0     0     0    0     0  8 
35 57  0
  0  0      0   5572  54844 142156    0    0     0     0    0     0  0 
0 100  0
  0  0      0   5572  54844 142156    0    0     0     0    0     0  0 
0 100  0
  0  0      0   5572  54848 142156    0    0     0    40    0     0  0 
0 100  0
  0  0      0   5588  54848 142156    0    0     0     0    0     0  0 
0 100  0
  0  0      0   5588  54848 142156    0    0     0     0    0     0  1 
1 98  0
  0  0      0   5588  54848 142156    0    0     0     0    0     0  7 
36 57  0
  0  0      0   5588  54848 142156    0    0     0     0    0     0  0 
0 100  0

And here the interrupts:

ss7-gate1:/var/log/asterisk# cat /proc/interrupts
            CPU0       CPU1
   0:  986934556          0    IO-APIC-edge  timer
   1:       1649          0    IO-APIC-edge  i8042
   7:          2          0    IO-APIC-edge  parport0
   9:          0          0   IO-APIC-level  acpi
  14:  182607673        347    IO-APIC-edge  ide0
  50:          0          0         PCI-MSI  pciehp
177:          0          0   IO-APIC-level  uhci_hcd
185:          0          0   IO-APIC-level  uhci_hcd, ehci_hcd
193:  986078651          0   IO-APIC-level  uhci_hcd, wct2xxp
201:          0          0   IO-APIC-level  uhci_hcd
209:    2640734          0   IO-APIC-level  eth1
225:   23208735          0   IO-APIC-level  eth0
NMI:          0          0
LOC:  986900234  986900230
ERR:          0
MIS:          0

Regards,
Kai

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