On Thu, Nov 17, 2011 at 1:08 PM, Templin, Fred L <fred.l.temp...@boeing.com> wrote: > Hi Chris, > > See below for some follow-up: > >> -----Original Message----- >> From: grow-boun...@ietf.org [mailto:grow-boun...@ietf.org] On >> Behalf Of Christopher Morrow >> Sent: Thursday, November 17, 2011 12:09 AM >> To: grow-cha...@tools.ietf.org; grow@ietf.org grow@ietf.org; >> Martin J. Levy >> Subject: [GROW] ixp jumbo frames doc >> >> We had a bit of a lively discussion in the meeting today about: >> <http://tools.ietf.org/html/draft-mlevy-ixp-jumboframes-00> >> >> Some of the topics covered were: >> o Is there a problem with CRC problems with 9k ? > > Please note that the concern is specifically for CRC-32. > Several works have discussed the error characteristics > of CRC-32 in relation to data set sizes: > > Koopman, P., "32-Bit Cyclic Redundancy Codes for > Internet Applications", Dec. 2002. > > Stone, J. & Partridge, C., "When the CRC and TCP > Checksum Disagree", Aug. 2000. > > Jain, R., "Error Characteristics of Fiber Distributed > Data Interface (FDDI), August 1990. > > Those works tend to support the assertion that CRC-32 > is adequate for data set sizes up to "about 9k or even > a little bit more". > > That said, I can easily imagine something stronger than > CRC-32, and it is the responsibility of the link layer > to provide adequate error checking if it intends to > support larger MTUs. > >> o is this something that the IEEE reigns supreme on? > > It is the link layer's job to ensure that it performs > adequate error checking for packets of various sizes; > it is not the network layer's place to guess at how well > the link layer is doing its job. So, the link layer's > advertised MTU is a certification that suitable error > detection will be performed for packets no larger than > the MTU; otherwise, it will become known as a "bad link". > >> o should there be other methods of deployment? > > Other methods of deployment than what? >
Sorry, I was rushing :( One of the proposals was to use a secondary VLAN at the exchange for 'larger' packets, one was to forklift the exchange, I believe there was a third discussed in the meeting as well. >> o is this a BCP instead of Informational doc? > > The document is proposing jacking up the Internet cell > size from 1500 to 9000, where 9000 seems like a good > fit for the vast majority of link paths anticipated > for the near future. That seems like BCP to me. Err, it's proposing setting the IXP interfaces to 'larger than 1500'. One of the problems is that some networks already show up at exchanges with 'larger than 1500 on their backbone/core facing interfaces, and likely on most other interfaces in the network as well, so these IXP interfaces are one-off situations :( I don't see this proposal as jacking up the whole of the Internet, there are still a vast number of edge interfaces which are not capable of changing MTU, but making the one-off problems go away seems like a good idea. > At the same time, at some point down the road we may > need to turn the crank again and jack up from 9000 > to something still larger. Hence, the BCP for the > near term should leave open the door for an update > at some point in the future. > >> o should this be adopted for WG work? > > Yes. thanks! -chris > Thanks - Fred > fred.l.temp...@boeing.com > >> We'll pass along a separate call for adoption as well, but keep these >> points in mind (and hopefully let's chat some about these as well) >> >> -chris >> (co-chair) >> _______________________________________________ >> GROW mailing list >> GROW@ietf.org >> https://www.ietf.org/mailman/listinfo/grow >> > _______________________________________________ GROW mailing list GROW@ietf.org https://www.ietf.org/mailman/listinfo/grow
