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Optical/IP

And Furthermore, Bill...

Bill, following on from my original open letter to you [now on page 2 of this column], I’d like to raise another issue concerning packet fragmentation, one that isn’t specific to Microsoft.

In fact, it’s something that the whole telecom/Internet industry needs to get its act together on, and it relates to a topic that’s high on the agenda of a lot of service providers: Virtual Private Networks.

In a nutshell, vendors need to come up with some standard ways of ensuring that their equipment can be configured to ensure that packets carrying streaming media won’t be dumped while they traverse a VPN tunnel. And in order for this to happen, service providers also need some rules on how to configure the hosts, switches, and routers so they all work in harmony when handling big packets.

I guess you may be wondering why I’m writing to you about this issue, if it concerns a whole host of other folk as well as Microsoft.

There are two reasons. First, it's folk using host software that experience the problems this creates, so you’re likely to get the blame even if it isn’t your fault. Second, someone needs to encourage the networking community to get its act together on streaming media, and I think you're just the hombre with the cojones to do this.

In the study that I cited in my original letter, the Cooperative Association for Internet Data Analysis (CAIDA) found that 16 percent of traffic flows were fragmented by tunneling technologies.

The basic problem here is that edge equipment sets maximum transmission units (MTUs) that are too big for the equipment at intermediate points in the tunnel. As the equipment typically can’t fragment packets in the middle of a tunnel, it drops the packets altogether.



One reason for this is that Path MTU Discovery – the protocol used to establish the MTU of a tunnel – sometimes doesn’t work. This may be because the host software or routers implement Path MTU Discovery in different ways.

The requirements for host software in this respect are laid down in a couple of ancient Internet Engineering Task Force (IETF) Requests for Comments – RFCs 1122 and 1123 – which date back to 1989! (I know there’ve been partial updates to these RFCs, but they don't address Path MTU Discovery.) The requirements for IP version 4 Routers (RFC 1812) are eight years old, and there’s no RFC at all covering IPv6 routers.

With such out-of-date or absent requirement RFCs, it’s hardly surprising that vendors end up implementing inconsistent approaches to Path MTU Discovery, which cause problems in practice. They’re often problems that drive service provider support staff wild, because “pings” in small packets can get through, while streaming media, contained in larger packets, can’t.



Another reason for Path MTU Discovery not working is that it’s often blocked by service providers anyhow. It’s part of the ICMP (Internet Control Message Protocol) family of protocols, and some service providers configure their equipment to block all ICMP packets because of security threats sometimes associated with the protocol family (for example, ping of death and smurf).

These Path MTU Discovery problems can happen with any VPN protocol, but there’s an added complication with Multiprotocol Label Switching (MPLS) VPNs. In some circumstances, intermediate routers can add an extra label to a packet, so that it becomes too big for the tunnel. (For an explanation of why this happens, see Note 2.)

The MPLS VPN problem is being addressed in an IETF Draft dealing with consistent MTU reporting for the Label Distribution Protocol (LDP). Work is nearly complete on this draft, being written by Ben Black of Layer 8 Networks and Kireeti Kompella of Juniper Networks Inc. (Nasdaq: JNPR). Work is already complete on the same feature for RSVP-TE (Resource Reservation Protocol – traffic engineering).

Many of the readers on the message board attached to this letter have urged increasing the Internet MTU to solve these issues. See, for example this message from celebrity poster Tony Li, Procket Networks Inc.’s chief scientist.

You can’t simply wave a magic wand and convert all Internet devices to larger MTUs. But by correct operation of the host software, routers, firewalls, load balancers, and all the other IP devices in the packet path, at least we can make the best of the MTUs that are supported today.

By the way, Bill, I really appreciate Microsoft’s David Caulton responding to the points made in my original open letter. In his post David raised a number of valid questions that I’ll respond to in due course, when I’ve got some feedback from various people. In other words, I haven't finished yet! (That's a promise, Bill, not a threat...)

Again, Microsoft (and, of course, any interested readers) may respond to these suggestions by either emailing me at [email protected] or contributing to the message board linked to this article.

And Bill? Bummer about that fine. Those Old Europeans just don't understand American Free Enterprise.

— Geoff Bennett, Director, Light Reading University

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mr zippy 12/4/2012 | 11:42:03 PM
re: And Furthermore, Bill... I use Linux.

Been Windows free for two years now.

Needed the disk space, hadn't run Windows for six months, deleted it.

If MS Office is holding you back from converting, have a look at the latest version of Open Office

http://www.openoffice.org

(sorry for the Linux plug, but LR insisted I put a message in, and I couldn't come up with anything further on the clippy / ipv4 fragment topic)
optical_man 12/4/2012 | 11:42:01 PM
re: And Furthermore, Bill... Am downloading Open Office, Windows version now. Will try it out.

Another free Office product (or was free last I checked) is Star Office by Sun Microsystems.

http://www.staroffice.com/

I have an old Dell lapttop, 500mhz (Latitude) that I'm looking to see what Linux can do, what do y'all suggest?
My friends say Linux is amazing in that it can work on an 'ancient' machine like my 500mhz. I'm willing to sacrifice the old beast for a Linux/Open Office/Star Office test.
If it runs like my 2Ghz machines, or even like a 1.5Ghz, I'll shout from the rooftops.

After that, I'll load my various VoIP systems onto it and report back....

Someone tell me what version of Free Linux to download.
Thanks.
mr zippy 12/4/2012 | 11:42:00 PM
re: And Furthermore, Bill... OpenOffice is the open source version of Star Office, much like Mozilla is (or was until AOL got into bed again with Microsoft) the open source version of Netscape Navigator.

500 Mhz laptop will be plenty powerful enough.

I've run Linux on a 386DX20 with 5 MB of RAM, 486DX33 with 8 MB of RAM, Cyrix P200 equivalent with 64 MB of RAM, and am currently running it on a Pentium 3 450 Mhz with 384 MB of RAM.

To push this thread somewhat back on topic, although I haven't had much of a chance to play with them properly, here are some VoIP etc. apps that run under Linux :

http://www.linphone.org/ - SIP Phone

http://www.gnomemeeting.org/ - H323 Video / VoIP

http://www.openh323.org/ - Open source H323 stack, and associated apps, eg IVR, Answering Machine, Gatekeeper

"Now, back to the regularly scheduled programming ..."

voiceoffire 12/4/2012 | 11:42:00 PM
re: And Furthermore, Bill... One option is to try www.linuxiso.org and burn your choice of linux on CDs. I have used Mandrake for many years, but you may hear from others why their choice is the best.

This download totals 3 CDs.

Have used staroffice on sun 5.6 for a couple of years. Not perfect, but useful.
mr zippy 12/4/2012 | 11:41:59 PM
re: And Furthermore, Bill... There is quite an active Linux discussion forum, part of the Whirlpool Broadband Community web site, here in Australia.

Feel free to seek or contribute answers.

http://www.whirlpool.net.au/

On a related note, Whirlpool has quite a reputation here, in particular as a place to go for generally un-biased advice or opinion on the Internet and broadband in Australia.

According to a recent survey, apparently it is "
the most popular source of IT news in Australia, according to objective Hitwise statistics. For the April-June period of 2003, www.whirlpool.net.au was ranked #1 in the 'News and Media - IT Media' category, based on number of visits."

Its run for free by Simon Wright, with a hosting provider donating bandwidth and server resources.

It would be interesting to know if there are other "community" oriented Internet and / or Broadband web sites / communities in other countries.
ironccie 12/4/2012 | 11:41:57 PM
re: And Furthermore, Bill... Geoff:

1) Why do you guys always do a great job of interacting very professionally with technology industry elite and the Light Reading readers don't have the courtesy to respect guys like Bill Gates and Bobby Johnson (recent comments on this same highlight article spot). I wish folks would be more respectful, it would make this a much better forum. Keep the good articles coming and hopefully folks will appreciate someone elses opinion without having to give their off topic opinions.

2) Fragmentation is a legacy problem and not a problem the new money in networking is facing. Heck, as your competitor I would hope Windows performance sucks on your network. Good job Bill! Please keep running your network without network management too (Hello MRTG fans!). How can you not know exactly what is going on every port of your network real time? I run Foundry at my house (old stuff, no sFlow yet) and connect with fiber to a service provider that is another Foundry shop (and yes, they run sFlow). I'm not seeing these problems, but some of the brightest companies with great business plans are seeing it. Some service providers in town have networks that resemble dinasour skeletons (pun intended). The smart ones are tearing out the legacy equipment and trying to build profitable services instead of following technology for technology sake. Would you like jumbo frames with that? With the hierarchy of cheap, simple Ethernet (10/100/1000/10000) and 802.3ad trunking, there is no excuse for a service provider or an enterprise to be fragmenting. I permit it the same way I permit poor customer service at a customer service counter. I go to another company. Bill, I say fix this because fragmentation is bad, but please don't hurry, I'm OK. Makes you wonder about the folks CAIDA was talking to though... Is UUNET^WWorldCom^WMCI still selling ATM? Man, there's an example of a technology that wasn't meant to bring long term profits and cause issues like fragmentation.

3) Linux fans don't worry, you are loved; however, please give Mr. Gates his right to be treated as an executive that puts food on the plates of more families than most farmers. If you think that Linux would be half as good as it is without Windows and the leadership of Mr. Gates, please think again. I still think computing would have never been the same without Amiga fans. We all have our place and if you don't like a technology, just put it over on the purple shelf and forget about it. Keep pushing and maybe you will build the perfect operating system. Until now, I haven't seen it. EVERY technology product has issues, including the beloved linux. Who was the first guy to go after the handicapped computing market? I believe that was Mr. Gates (and company) wasn't it?

-- IronCCIE
hyperunner 12/4/2012 | 11:41:56 PM
re: And Furthermore, Bill... Does anyone get how this works?

Back on '95 it seemed easy. You right clicked on a drive or folder, chose "sharing" and set up the options (read or write, allowed users and passwords).

It seems like each version of Windows uses a different terminology and architecture for its security. Surely this can't be healthy? Unlike Linux, Windows is supposed to be "easy" - users should have to learn how to program in C just to install a new application. They shouldn't need to learn how to use VI just to set security permissions.

In theory it's all there, somewhere in a dialogue box, but it's a case of finding the right dialogue box, and understand what security terminology Microsoft are using in this version.

hR.
pdt 12/4/2012 | 11:41:55 PM
re: And Furthermore, Bill... I think microsft email protocol exchange must have very bad behaviur on the network.

If you use this protocol on a LAN the performance is OK and the functionality is better than SMTP/POP.

But on a modem link the exchange does many things in an inefficient way. and this takes a very long time for task like synchronising.

I do not like to use Microsoft mail when I am away from the office or my home ADSL. But I have no choise becase MIS department has decided on Microsoft. They have shut down POP mail servers and support only exchange.

I think programmers at Microsoft who develop exchange and outlook never use modem - only Fast Ethernet :-)
gbennett 12/4/2012 | 11:41:55 PM
re: And Furthermore, Bill... At the risk of starting a flood of off-topic replies...

I do sympathise with the views expressed in the first five posts. For the right kind of person, Linux is a valid replacement for Windows, as well as being a lot more than that for server use.

I ran a Red Hat system on a 200MHz Pentium Pro for several years, but for real work I always went back to Windows. For me the killer app was Powerpoint, closely followed by Word.

I haven't used the latest Linux office equivalents you mention, but IMHO if Linux really wants to be a Windows replacement, the developers should forget about O/S features for a few months and get working on the Office suite.

Cheers,
Geoff
hyperunner 12/4/2012 | 11:41:55 PM
re: And Furthermore, Bill... Hey, that was me! How dare you call me decent? :-)

I still say Boby is a bit too fond of the first person, singular. Actually I might have even said that to his face, just so long he wasn't deciding my pay rise :-)

hR.

P.S. I'm a him, or a reasonable facsimile thereof.

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