[SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)

Fri May 23 19:32:17 EDT 2008

Please don't misunderstand me; I'm an advocate of TCP, see attached.  I
wanted to point out the costs to highlight that when people are
permitted a choice, most seem to go with quick/cheap over
strong/expensive.  We'd do well to trot out the "carrier grade" banner
and remove that choice completely.  My guess is that if HTTP did not
"presume a reliable transport"(1), we'd see some implementations trying
to save a few cycles by running over UDP.

If TCP is more costly, then I see it as a necessary cost of doing things
correctly.

I think that SIP is indeed special, in as much as it is the only other
Internet protocol that I can think of that is measured by its users
against the reliability and security of the SS7-driven PSTN.  That's a
very high standard to meet, so I advocate adding reliability and
security at every possible level.

When a protocol that provides more reliability, security, and
availability than TCP comes out, I'll be a fan.

Thanks,

David Hiers

CCIE (R/S, V), CISSP
ADP Dealer Services
2525 SW 1st Ave.
Suite 300W
Portland, OR 97201
o: 503-205-4467
f: 503-402-3277

(1) RFC 2616, 1.4

________________________________

From: Francois Audet [mailto:audet at nortel.com] 
Sent: Friday, May 23, 2008 3:40 PM
To: Hiers, David; Russell Bennett; techwg at sipforum.org
Subject: RE: [SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)

Damned! 

That must mean all the Web Servers out there running HTTP/TCP are wrong!

The whole World Wide Web is wrong and should move to UDP!

This SIP-is-special argument is silly and not supported by facts.

________________________________

	From: techwg-bounces at sipforum.org
[mailto:techwg-bounces at sipforum.org] On Behalf Of Hiers, David
	Sent: Friday, May 23, 2008 14:46
	To: Russell Bennett; techwg at sipforum.org
	Subject: Re: [SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)

	TCP may be supported, but it can be costly.  As I mentioned in a
previous post, there can be scaling differences between implementations
of UDP and TCP.

	Here's a nice paper on a test of one implementation:

http://www.research.ibm.com/people/n/nahum/papers/sigmetrics07-sip-perf.
pdf

	While not directly related to SIP Trunking, the results are
nevertheless interesting.

	One of my vendors reports a 25% hit when moving from UDP to TCP,
with some TCP-specific ugliness when failing over between redundant
systems. 

	I'm a fan of reliability, and would really like to be *forced*
into running the most reliable transport protocol possible (TCP, SCTP,
etc).  However, as long as UDP is an option that can scale to greater
loads on the same platform, there canl be considerable budgetary
pressure to run UDP.

	Thanks,

	David Hiers

	CCIE (R/S, V), CISSP
	ADP Dealer Services
	2525 SW 1st Ave.
	Suite 300W
	Portland, OR 97201
	o: 503-205-4467
	f: 503-402-3277

________________________________

	From: techwg-bounces at sipforum.org
[mailto:techwg-bounces at sipforum.org] On Behalf Of Russell Bennett
	Sent: Friday, May 23, 2008 11:54 AM
	To: techwg at sipforum.org
	Subject: Re: [SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)

	This has been a pretty long thread.  I think that almost
everyone is in agreement that both UDP and TCP are both required in
SC1.1, with a bias towards TCP as a REALLY MUST (or whatever language we
choose) and UDP for backwards compatibility.

	I just wanted to respond to one issue that has been raised
several times: that only UDP is supported by the majority of SIP
deployments.  

	I did some research on this and, while it is impossible to get
data on current installed base, I have been able to determine what would
be deployed today with existing product from the overwhelming majority
market share vendors.  Therefore, even if a customer had older equipment
from a given vendor that only supported UDP, they have the option to
upgrade to newer equipment that supports TCP or TLS.

	So, the notion that anyone is somehow constrained from
supporting TCP (and even TLS) is invalid.

	Russell

Vendor

UDP

TCP

TLS

Reference

Microsoft

N

Y

Y

http://download.microsoft.com/download/d/b/6/db641148-427b-41d3-9f20-7ff
bddaf65b8/OCS_VoIP_Guide.doc
<http://download.microsoft.com/download/d/b/6/db641148-427b-41d3-9f20-7f
fbddaf65b8/OCS_VoIP_Guide.doc>  

Cisco

Y

Y

Y

http://www.cisco.com/en/US/docs/ios/12_4t/12_4t11/FeatTLS.html#wp1092137
<http://www.cisco.com/en/US/docs/ios/12_4t/12_4t11/FeatTLS.html#wp109213
7>  

IBM

N

Y

Y

http://download.boulder.ibm.com/ibmdl/pub/software/dw/lotus/sametime-sip
.pdf
<http://download.boulder.ibm.com/ibmdl/pub/software/dw/lotus/sametime-si
p.pdf>  

Nortel

Y

Y

Y

http://www142.nortelnetworks.com/techdocs/CS1K_5_0/pdf/NN43001-564_01.05
_NRS.pdf
<http://www142.nortelnetworks.com/techdocs/CS1K_5_0/pdf/NN43001-564_01.0
5_NRS.pdf>  

Avaya

Y

Y

Y

http://www.avaya.com/gcm/master-usa/en-us/products/offers/sip_enablement
_services.htm&View=ProdTechSpec
<http://www.avaya.com/gcm/master-usa/en-us/products/offers/sip_enablemen
t_services.htm&View=ProdTechSpec>  

Alcatel-Lucent

Y

Y

N

http://www1.alcatel-lucent.com/doctypes/articlepaperlibrary/pdf/ATR2002Q
4/T0212-SIP_Technology-EN.pdf
<http://www1.alcatel-lucent.com/doctypes/articlepaperlibrary/pdf/ATR2002
Q4/T0212-SIP_Technology-EN.pdf>  

Siemens

Y

Y

Y

http://www.enterprise-communications.siemens.com/Products/Phones%20Clien
ts/Desktop%20Phones/~/media/6DAA007008EB4A5CA0212A6D12A49770.ashx
<http://www.enterprise-communications.siemens.com/Products/Phones%20Clie
nts/Desktop%20Phones/~/media/6DAA007008EB4A5CA0212A6D12A49770.ashx>  

AudioCodes

Y

Y

Y

http://www.audiocodes.com/objects/sbc/nCite_4000.pdf
<http://www.audiocodes.com/objects/sbc/nCite_4000.pdf>  

Nextpoint

Y

Y

Y

http://www.nextpointnetworks.com/files/NextPoint_SBC_USLTR_2008_hirez.pd
f
<http://www.nextpointnetworks.com/files/NextPoint_SBC_USLTR_2008_hirez.p
df>  

Acme Packet

Y

Y

Y

http://www.acmepacket.com/html/page.asp?PageID={06E4AEBC-24E2-46CC-BA95-
7C74288FA45B}
<http://www.acmepacket.com/html/page.asp?PageID=%7b06E4AEBC-24E2-46CC-BA
95-7C74288FA45B%7d>  

Covergence

Y

Y

Y

http://www.covergence.com/stuff/contentmgr/files/4adf40f79f81482fff714c4
6d8e06832/misc/ssesb.pdf
<http://www.covergence.com/stuff/contentmgr/files/4adf40f79f81482fff714c
46d8e06832/misc/ssesb.pdf>  

	-----Original Message-----
	From: techwg-bounces at sipforum.org
[mailto:techwg-bounces at sipforum.org] On Behalf Of Peter Dunkley
	Sent: Thursday, May 22, 2008 6:40 AM
	To: Eric Burger; techwg at sipforum.org
	Subject: Re: [SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)

	That would depend on whether you consider ISDN, and the like, to
be SIP related or not :-)

	On a more serious note there is a requirement for tunnelling
UK-ISUP within SIP messages.  Also, UK-ISUP has recently been extended
to allow BT-NUP messages to be tunnelled within - specifically so that
BT-NUP can be passed across a SIP network for legacy interworking.  This
would result in SIP messages that can contain UK-ISUP messages, that can
contain BT-NUP messages, which may contain DPNSS messages...

	What you jokingly mentioned below is absolutely horrible - but
(within a national context) not as unlikely as it may seem!

	I have also heard of some interest in directly tunnelling DPNSS
within SIP as well.

	However, I would be the first to admit that BT-NUP and so on
have no place in a SIPconnect recommendation.

	Peter

	-----Original Message-----

	From: techwg-bounces at sipforum.org
[mailto:techwg-bounces at sipforum.org]On

	Behalf Of Eric Burger

	Sent: 22 May 2008 10:17

	To: techwg at sipforum.org

	Subject: Re: [SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)

	I would offer this philosophy would lead us to standardize
SIPconnect

	1.1 to use ISDN, possibly choosing Q.921, Q.sig, or BT-NUP :-)

	On May 21, 2008, at 10:24 AM, Peter Dunkley wrote:

	> In my opinion any recommendation needs to take into account
not just

	> best practice, but actual practice.  Vilifying, or making life

	> difficult, for those who have pragmatically chosen something

	> different, and invested time and money in making it work, is
not

	> going to contribute to the success of any recommendation.

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