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