Session Announcement Proto col Colin P erkins < c.p - - PowerPoint PPT Presentation

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Session Announcement Proto col Colin P erkins < c.p - - PowerPoint PPT Presentation

Sep 20, 2022 477 likes •636 views

Session Announcement Proto col Colin P erkins < c.p erkins@cs.ucl.ac.uk > Depa rtment of Computer Science Universit y College London Go w er Street London W C1E 6BT The new SAP draft The current sp ec

slide-1
SLIDE 1 Session Announcement Proto col Colin P erkins <c.p erkins@cs.ucl.ac.uk> Depa rtment
  • f
Computer Science Universit y College London Go w er Street London W C1E 6BT
slide-2
SLIDE 2 The new SAP draft The current sp ec (draft-ietf-mmusic-sap-v2-01.txt) is a merger
  • f
  • draft-ietf-mmusic-sap-00.txt
(from Novemb er 1996!)
  • draft-ietf-mmusic-sap-sec-04.txt
  • draft-ietf-mmusic-sap-v2-00.txt
Aiming to get an exp erimental RF C
  • ut
relatively so
  • n.
Colin P erkins/SAPv2-01/1
slide-3
SLIDE 3 Overview
  • f
changes
  • Supp
  • rt
fo r IPv6 and directo ry sessions
  • Up
date address/p
  • rt
usage
  • Up
date bandwidth recommendations
  • Comp
ression using zlib
  • P
a yload t yp e eld
  • Authenticated
announcements
  • Asso
rted mino r bug-xes Colin P erkins/SAPv2-01/2
slide-4
SLIDE 4 Supp
  • rt
fo r IPv6
  • Add
an address t yp e bit to the SAP header and allo w the
  • riginating
source eld to b e an IPv6 address
  • The
IPv6 SAP address is FF0X:0:0:0:0:0 :2: 7FFE, where X is the 4-bit scop e value. The follo wing scop e values a re dened in IPv6: V alue Scop e 0x1 No de-lo cal 0x2 Link-lo cal 0x5 Site-lo cal 0x8 Organization-lo cal 0xE Global Colin P erkins/SAPv2-01/3
slide-5
SLIDE 5 Directo ry Sessions
  • Allo
w SAP directo ries to b e announced within SAP { due to Ross Finla yson.
  • SDP
syntax: v=0
  • =cperkin
s 28908445 26 289084280 7 IN IP4 126.16.6 4.4 s=Sample directory session m=directo ry 9875 SAP applicatio n/s dp c=IN IP4 224.2.127. 12 /25 5 t=2873397 496 28734046 96
  • Announced
b y SAP in the usual manner. Colin P erkins/SAPv2-01/4
slide-6
SLIDE 6 Directo ry Sessions
  • Any
  • ne
ma y announce sessions within a directo ry { Do w e w ant to restrict this?
  • Changes
to the announcement
  • f
the directo ry MUST b e authenticated { If the directo ry is deleted, MUST stop announcing sessions within it { If the directo ry moves, MUST move announcements
  • f
sessions to the new group Colin P erkins/SAPv2-01/5
slide-7
SLIDE 7 P
  • rts
and TTLs
  • Announcements
MUST use p
  • rt
9875 with TTL 255.
  • Previous
versions allo w ed TTL scoping
  • w
e do not
  • and
admin scop ed sessions w ere allo w ed to sp ecify a dierent p
  • rt.
  • What
do current implementations do? Colin P erkins/SAPv2-01/6
slide-8
SLIDE 8 Bandwidth recommendation s
  • Bandwidth
limit fo r each group is no w 4 kbps
  • p
revious versions used 200 bps fo r global scop e groups, and 2 kbps fo r lo cal groups.
  • Minimum
timeout is increased from 30 minutes to 1 hour. Colin P erkins/SAPv2-01/7
slide-9
SLIDE 9 Comp ression
  • Sp
ecify zlib instead
  • f
gzip.
  • Use
  • f
gzip w as a mistak e, and
  • nly
implementation used zlib. Colin P erkins/SAPv2-01/8
slide-10
SLIDE 10 P a yload t yp e W e no w allo w an
  • ptional
pa yload t yp e to b e included in each announcement.
  • Ma
y b e
  • mmitted,
in which case default is SDP
  • All
implementations MUST supp
  • rt
application/SDP
  • Use
  • f
non-SDP pa yloads is NOT RECOMMENDED due to interop erabilit y concerns Colin P erkins/SAPv2-01/9
slide-11
SLIDE 11 Encryption
  • The
SAP header retains a single bit to indicate that the pa yload is encrypted.
  • W
e do not sp ecify any encryption algo rithms in this draft: leave to
  • ther
drafts if supp
  • rt
is desired.
  • Encrypted
announcements a re NOT RECOMMENDED
  • n
groups where there ma y b e many receivers without the decryption k ey , due to w aste to bandwidth. Colin P erkins/SAPv2-01/10
slide-12
SLIDE 12 Authenticatio n
  • Sp
ecify authentication using either Op enPGP
  • r
CMS
  • As
in SAP securit y drafts, but up dated fo r new versions
  • f
the authentication sp ecs. Colin P erkins/SAPv2-01/11
slide-13
SLIDE 13 P ack et fo rmat 1 2 3 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+
  • +-+-+-
+-+-+-+- +-+-+-+
  • +-+-+-+
  • +-+-+-+
| V=1 |A|R|T|E|C| auth len | msg id hash | +-+-+-+-+-+-+-+-+-+-+-+-+-+
  • +-+-+-
+-+-+-+- +-+-+-+
  • +-+-+-+
  • +-+-+-+
| | :
  • riginating
source (32
  • r
128 bits) : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+
  • +-+-+-
+-+-+-+- +-+-+-+
  • +-+-+-+
  • +-+-+-+
|
  • ptional
authentication header | : .... : +-+-+-+-+-+-+-+-+-+-+-+-+-+
  • +-+-+-
+-+-+-+- +-+-+-+
  • +-+-+-+
  • +-+-+-+
|
  • ptional
timeout | *-*-*-*-*-*-*-*-*-*-*-*-*-*
  • *-*-*-
*-*-*-*- *-*-*-*
  • *-*-*-*
  • *-*-*-*
|
  • ptional
payload type | + +-+-
  • +
| |0| | +
  • +-+
| | | : payload : | | +-+-+-+-+-+-+-+-+-+-+-+-+-+
  • +-+-+-
+-+-+-+- +-+-+-+
  • +-+-+-+
  • +-+-+-+
Colin P erkins/SAPv2-01/12
slide-14
SLIDE 14 Op en Issues
  • Should
the SDP syntax fo r directo ry sessions b e dened here?
  • Calculation
  • f
announcement interval is not w ell sp ecied Colin P erkins/SAPv2-01/13