Size of the Recv-Q of TCP socket gets increased

Hi,

 

After I send alarm/trap each time from the sub-agent to master agent on
net-snmp platform, the size of the Recv-Q of the source socket gets
increased as follows:

 

[root@nas1 root]# netstat -ap | grep 1055

tcp        0      0 localhost.localdom:1055 *:*
LISTEN      17367/snmpd

tcp     5648      0 localhost.localdo:34976 localhost.localdom:1055
ESTABLISHED 17382/proSWagntdGSA

tcp        0      0 localhost.localdom:1055 localhost.localdo:34976
ESTABLISHED 17367/snmpd

 

After sending alarm:

 

[root@nas1 root]# netstat -ap | grep 1055

tcp        0      0 localhost.localdom:1055 *:*
LISTEN      17367/snmpd

tcp     7152      0 localhost.localdo:34976 localhost.localdom:1055
ESTABLISHED 17382/proSWagntdGSA

tcp        0      0 localhost.localdom:1055 localhost.localdo:34976
ESTABLISHED 17367/snmpd

 

snmpd (master agent) sends unexpected response after every snmp trap
sent from subagent using a shared library.

 

[root@nas1 root]# tcpdump -i lo port 34976 -s 1500 -w /var/log/dump1.txt

tcpdump: listening on lo

 

12 packets received by filter

0 packets dropped by kernel

 

[root@nas1 root]# tcpdump -v -r /var/log/dump1.txt

23:59:10.162329 localhost.localdomain.34976 >
localhost.localdomain.1055: P [bad tcp cksum 42db!] 744:1488(744) ack
753 win 30511 <nop,nop,timestamp 43270216 43270113> (DF) [ttl 0] (id
17963, len 796)

23:59:10.162873 localhost.localdomain.1055 >
localhost.localdomain.34976: P [bad tcp cksum c986!] 753:1505(752) ack
1488 win 32767 <nop,nop,timestamp 43270216 43270216> (DF) [ttl 0] (id
24898, len 804)

23:59:10.162909 localhost.localdomain.34976 >
localhost.localdomain.1055: . [tcp sum ok] ack 1505 win 29759
<nop,nop,timestamp 43270216 43270216> (DF) [ttl 0] (id 17964, len 52)

 

As a result receiving queue is growing, getting overflowed and we stop
sending SNMP traps further.

 

Is there any way to prevent this response to be delivered to subagent?

Is there any API to drain receiving queue?

 

What is the recommendation for troubleshooting?

Please help me.

 

OS details:

 

[progeny@nas1 app]$ uname -a

Linux nas1 2.4.21-15.ELsmp #1 SMP Thu Apr 22 00:18:24 EDT 2004 i686 i686
i386 GNU/Linux

[progeny@nas1 app]$ cat /etc/redhat-release

Red Hat Enterprise Linux WS release 3 (Taroon Update 2)

 

Net_SNMP version used:

 

[progeny@nas1 app]$ rpm -qa | grep -i net-snmp

net-snmp-devel-5.0.9-2.30E.3

net-snmp-5.0.9-2.30E.3

net-snmp-utils-5.0.9-2.30E.3 

 

[root@nas1 root]# /usr/sbin/snmpd -version

 

NET-SNMP version:  5.0.9

Web:               http://www.net-snmp.org/

Email:             [email protected]

 

Thanks

 



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