--- 1/draft-ietf-v6ops-pmtud-ecmp-problem-01.txt 2015-06-17 22:14:59.123034547 -0700 +++ 2/draft-ietf-v6ops-pmtud-ecmp-problem-02.txt 2015-06-17 22:14:59.143035020 -0700 @@ -1,21 +1,21 @@ v6ops M. Byerly Internet-Draft Fastly Intended status: Informational M. Hite -Expires: November 20, 2015 Evernote +Expires: December 19, 2015 Evernote J. Jaeggli Fastly - May 19, 2015 + June 17, 2015 Close encounters of the ICMP type 2 kind (near misses with ICMPv6 PTB) - draft-ietf-v6ops-pmtud-ecmp-problem-01 + draft-ietf-v6ops-pmtud-ecmp-problem-02 Abstract This document calls attention to the problem of delivering ICMPv6 type 2 "Packet Too Big" (PTB) messages to the intended destination in ECMP load balanced or anycast network architectures. It discusses operational mitigations that can be employed to address this class of failure. Status of This Memo @@ -26,21 +26,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on November 20, 2015. + This Internet-Draft will expire on December 19, 2015. Copyright Notice Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -186,22 +186,25 @@ traffic) and sensible ingress rate limiters which will discard excessive message volume can be applied to protect even very large anycast server tiers with the potential for fallout only under circumstances of deliberate duress. 3.1. Alternatives As an alternative, it may be appropriate to lower the TCP MSS to 1220 in order to accommodate 1280 byte MTU. We consider this undesirable as hosts may not be able to independently set TCP MSS by address- - family thereby impacting IPv4, or alternatively that it relies on a - middle-box to clamp the MSS independently from the end-systems. + family thereby impacting IPv4, or alternatively that middle-boxes + need to be employed to clamp the MSS independently from the end- + systems. Potentialy, extension might further alter the lower bound + that the mss would have to be set to making clamping still more + undesirable. 3.2. Implementation 1. Filter-based-forwarding matches next-header ICMPv6 type-2 and matches a next-hop on a particular subnet directly attached to both border routers. The filter is policed to reasonable limits (we chose 1000pps more conservative rates might be required in other imlementations). 2. Filter is applied on input side of all external interfaces