Re: Maybe I'm misreading this but...
In article <4.0.1.19981016224901.00de6240@pariah.cncx.com>, I Am Not An Isp <patrick@ianai.net> wrote:
FACT: RFC1918 space does not break PMTU discovery. Deal with it.
If you use RFC 1918 space on the Internet, PMTU very well may not work for you. You can place fault on whatever standard you like but that doesn't change the *operational* issue. -- Shields, CrossLink.
At 08:07 PM 10/17/98 +0000, Michael Shields wrote:
In article <4.0.1.19981016224901.00de6240@pariah.cncx.com>, I Am Not An Isp <patrick@ianai.net> wrote:
FACT: RFC1918 space does not break PMTU discovery. Deal with it.
If you use RFC 1918 space on the Internet, PMTU very well may not work for you. You can place fault on whatever standard you like but that doesn't change the *operational* issue.
Mark and I have discussed this in private. I believe this has devolved into an argument over semantics. Assume you use RFC1918 addressing in a private enterprise. PMTU-D will work without a problem within that enterprise (unless you filter your own routers). QED: RFC1918 does not break PMTU-D. However, if packets from RFC1918 ports leave the enterprise, then there is a very real possibility those packets will be filtered on other networks. These filters are in no way wrong, bad or otherwise a problem. It's just something you have to deal with "operationally". So, using RFC1918 addresses on router ports which have any possibility of send packets (even ICMP one-way communication) to other networks may find their packets filtered. This means that things like PMTU-D will break. Not using RFC1918 addressing reduces this possibility because (as Mark pointed out) these filters are recommended by the RFC. Does that make everyone happy? Can we get back to our regularly scheduled furniture, carpet and spam discussions? :)
Shields, CrossLink.
TTFN, patrick I Am Not An Isp www.ianai.net "Think of it as evolution in action." - Niven & Pournelle
On 17 Oct 1998, Michael Shields wrote:
In article <4.0.1.19981016224901.00de6240@pariah.cncx.com>, I Am Not An Isp <patrick@ianai.net> wrote:
FACT: RFC1918 space does not break PMTU discovery. Deal with it.
If you use RFC 1918 space on the Internet, PMTU very well may not work for you. You can place fault on whatever standard you like but that doesn't change the *operational* issue.
1) There is nothing inherient in the use of RFC 1918 space that will break PMTU. 2) In the real world, many providers filter RFC 1918 space, which has a good chance of breaking PMTU. There, everyone is right. Can we all put our genitalia away and move on? /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ Patrick Greenwell (800) 299-1288 v CTO (925) 377-1212 v NameSecure (925) 377-1414 f Coming to the ISPF? The Forum for ISPs by ISPs http://www.ispf.com \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
On Sun, 18 Oct 1998, Patrick Greenwell wrote:
On 17 Oct 1998, Michael Shields wrote:
In article <4.0.1.19981016224901.00de6240@pariah.cncx.com>, I Am Not An Isp <patrick@ianai.net> wrote:
FACT: RFC1918 space does not break PMTU discovery. Deal with it.
If you use RFC 1918 space on the Internet, PMTU very well may not work for you. You can place fault on whatever standard you like but that doesn't change the *operational* issue.
1) There is nothing inherient in the use of RFC 1918 space that will break PMTU.
The only point I am trying to make is that while there is absolutely nothing in using address space as defined in RFC-1918 that will break PMTU-D, using 1918 addresses for public router interfaces which send packets to public networks (in this case, the Internet) from that address is outside the scope of what 1918 permits and can break things when combined with other entirely legitimate and correct practices. As a result, it is unwise to encourage people to use 1918 addresses in such an inappropriate way. Since everyone agrees on this, hopefully this thread can now rest.
participants (4)
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I Am Not An Isp -
Marc Slemko -
Patrick Greenwell -
shields＠crosslink.net