Static Protocols - 3Com MSR 50 Series Configuration Manual

1702 C 90: DAR C
HAPTER

Static Protocols

ONFIGURATION
Figure 483 compound RTCP packet format
As shown in the above figure, the random 32-bit prefix in the header exists only
when the RTCP packet is encrypted. This is because the packet, if encrypted, no
longer has the features of RTCP packet, and requires no special processing. Each
packet in the figure indicates an RTCP packet, and there is no interval between
RTCP packets. The first RTCP packet in the compound RTCP packet must be SR
type or RR type. The header structure of SR type is shown in
Figure 484 Header structure of SR-type RTCP packet
0 2 3
V P RC
The fields are described as follows:
V: 2 bits, version number.
■
P: 1 bit, padding flag.
■
RC: 5 bits, the number of receiving report blocks in the RTCP packet.
■
PT: 8 bits, RTCP packet type flag; it is 200 for the SR-type RTCP packet.
■
length: 16 bits, length of the RTCP packet.
■
SSRC of sender: 32 bits, SSRC of the sender.
■
The structure of the RR-type RTCP packet header is similar with that of the SR
type, except that the PT field of RR type is 201.
There are some protocols above the TCP and UDP protocols, which are determined
by the TCP or UDP port numbers. See the following table for their names and
default port numbers.
Static port protocols
Protocol name
BGP
Citrix
Citrix
CU-SeeMe
CU-SeeMe
DHCP/BOOTP
8 9 16
PT=SR=200
SSRC of Sender
Protocol type
TCP/UDP
TCP
UDP
TCP
UDP
UDP
Figure 484.
Length
Port number
179
1494
1604
7648, 7649
7648, 7649, 24032
67, 68
31