On 6/26/2013 1:09 PM, Linda Dunbar wrote:
Ron,
Those applications ignore the ICMP messages and keep sending data
frames as if there is no ICMP message received.
We ran into this problem in testing Video distribution system. After
the first few frames, the receivers can't receive anything. After
lengthy debugging, we found out that an intermediate node drops packets
when GRE encapsulated frames exceed the link MTU. We tested that ICMP
message is sent back, but the source node didn't respond. We tried
several setting as Joe pointed out. Some guest OSs change behavior, some
don't.
Who to fix in this situation depends on how the ICMPs received are being
handled.
Are they being sent to the transport layer?
Is the app tracking the errors?
It might or might not be the OS's fault.
Joe
Linda
-----Original Message-----
From: Ronald Bonica [mailto:[email protected]]
Sent: Wednesday, June 26, 2013 8:00 AM
To: Linda Dunbar; Joe Touch; Carlos Pignataro (cpignata)
Cc: Internet Area
Subject: RE: [Int-area] New Version Notification for draft-bonica-
intarea-gre-mtu-00.txt
Linda,
What do these platforms do when they receive an ICMP Packet too big
from a router that isn't a tunnel ingress?
Ron
-----Original Message-----
From: Linda Dunbar [mailto:[email protected]]
Sent: Tuesday, June 25, 2013 10:05 AM
To: Joe Touch; Carlos Pignataro (cpignata)
Cc: Ronald Bonica; Internet Area
Subject: RE: [Int-area] New Version Notification for draft-bonica-
intarea-gre-mtu-00.txt
Ron,
Your draft recommends that the ingress node discards the frame and
sends ICMP msg to the source node when the size of GRE encapsulated
frame exceeds link MTU.
We experienced that Window XP doesn't adjust frame size after
receiving
ICMP message. Many Linux based applications don't do anything either
with the MTU ICMP message. I think your draft should point those
issues
out and recommend fragmentation approach under those circumstances.
Linda
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