> On 7/11/08 1:58 PM, Dan Wing wrote: > >> Elwell, John wrote: > >> > >>> Which would be ideal, if we were sure of getting them > >>> through service providers unchanged. > >>> > >> Therein lies the conundrum with intermediate manglers like B2BUA's > >> and mailing lists managers, etc. > >> > > > > It is the conundrum for the entire Internet -- TCP 'protocol > > scrubbers' exist, TCP options get dropped, DSCP bits get changed, > > ECN bits are mangled, and Router Alert Option gets dropped. > > > > Such is the reality. I wish it weren't the reality, too. > > So... are groups within TSV proposing new extension header fields to > carry things like "orginal diffserv codepoint" with the hope that TCP > protocol scrubbers won't mess them up?
http://tools.ietf.org/html/rfc3168#section-8 This section considers the issues when a router is operating, possibly maliciously, to modify either of the bits in the ECN field. We note that in IPv4, the IP header is protected from bit errors by a header checksum; this is not the case in IPv6. Thus for IPv6 the ECN field can be accidentally modified by bit errors on links or in routers without being detected by an IP header checksum. By tampering with the bits in the ECN field, an adversary (or a broken router) could do one or more of the following: falsely report congestion, disable ECN-Capability for an individual packet, erase the ECN congestion indication, or falsely indicate ECN-Capability. Section 18 systematically examines the various cases by which the ECN field could be modified. The important criterion considered in determining the consequences of such modifications is whether it is likely to lead to poorer behavior in any dimension (throughput, delay, fairness or functionality) than if a router were to drop a packet. ... -d _______________________________________________ Sip mailing list https://www.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [EMAIL PROTECTED] for questions on current sip Use [EMAIL PROTECTED] for new developments on the application of sip
