Packet Padding

Hey,

I want to learn more about how to implement software based on the MSN
protocol. However, I'm confused about one thing.

When I execute a "sudo tcpdump -i eth0 -s 1500 -w msnlog" to see what
the packets look like, I get a lot of junk between the usefull data.
eg:

^@L^\uffffW^BJg\uffffMSG 3 A 157^M
MIME-Version: 1.0^M
Content-Type: text/plain; charset=UTF-8^M
User-Agent: Gaim/1.2.1^M
X-MMS-IM-Format: FN=MS%20Sans%20Serif; EF=; CO=0; PF=0^M
^M
testing
testing^\uffff^\uffff\uffffB\uffffk^H^@I^@^@^@I^@^ @^@^@^P\uffff^\u05e4)^@P\uffff^\
u05e1\uffff^H^@E^@^@;^\uffffv^@^@k^F(\uffff\uffff. ^F^\uffff\uffff\uffff^@^D^GG\
uffff^\uffffH\uffff\u0120\uffff\uffff\uffff
^\uffff^X\uffff^DW^K^@^@^A^A^H
^BJg\uffff^@L^\uffffWACK 3^M
^\uffff^\uffff\uffffB^Kl^H^@\uffff^@^@^@\uffff^@^@ ^@^@P\uffff^\u05e1\
uffff^@^P\uffff^\u05e4)^H^@E^@^@4\uffff\uffffiM@@^ F\uffff\uffff:^\uffff
\uffff\uffff^@^D\uffff.^F^\uffff\uffff^\uffff^GG\u ffff\uffff\uffff
H\uffff\u0127^\uffff^X^E\uffff ^@^@^A^A^H
^@L^\uffff^@^BJg\uffffMSG 4 U 96^M


Clearly, the usefull information is there (sending a message), but what
is with all the padding around the information? How come it's not as
clean and simple as some of the protocol guides tell me? Could it be
hex notation for something?


Thanks