unusual packet (tcpdump shows): rad-#0 41 [id 0] Attr[

Dear sir.

I'm facing this packets continuously on my server.
Can someone please explain me what these packets r and for what 
they r used?
is this possibly a DDOS attack??

the sample tcpdump output is:

20:32:22.658735 200.213.38.137.1812 > XX.XX.XX.XX.1812:  rad-#0 41 
[id 0] Attr[  Term_action Term_action Term_action Term_ac
tion Term_action Term_action Term_action Term_action Term_action 
Term_action Term_action

second time tcpdump

20:39:57.168735 202.30.10.188.1812 > XX.XX.XX.XX.1812:  rad-#0 41 
[id 0] Attr[  Term_action



This Line Term_action goes on till infinity (or may b till run out 
of buffers)

Means these packets are coming from a different different Ip 
addresses ...

I'm not running anything on 1812 port (neither udp or tcp)
Does above packet mean another protocol than udp/tcp ??

can someone please explain me the above problem ...

i'm getting worried about the traffic coming to my servers ....

Thanking you,
Mobby



----------------------------------------------------------------------------
This list is provided by the SecurityFocus ARIS analyzer service.
For more information on this free incident handling, management 
and tracking system please see: http://aris.securityfocus.com