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[lwip-devel] [bug #47652] there is always a delay to send the first Neig
From: |
shu chen |
Subject: |
[lwip-devel] [bug #47652] there is always a delay to send the first Neighbor Solicitation for the new add INCOMPLETE state neighbor entry |
Date: |
Sat, 09 Apr 2016 00:15:28 +0000 |
User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.110 Safari/537.36 |
URL:
<http://savannah.nongnu.org/bugs/?47652>
Summary: there is always a delay to send the first Neighbor
Solicitation for the new add INCOMPLETE state neighbor entry
Project: lwIP - A Lightweight TCP/IP stack
Submitted by: chenshu
Submitted on: Sat 09 Apr 2016 12:15:27 AM GMT
Category: IPv6
Severity: 3 - Normal
Item Group: Faulty Behaviour
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Planned Release:
lwIP version: git head
_______________________________________________________
Details:
The bug is found during the ping test in our project, all the first ping to
the new neighbor exceeds one second.
In the current Neighbor Discovery implementation of LwIP, there is always a
delay to send the first Neighbor Solicitation for the new add INCOMPLETE state
neighbor entry. The delay blocks all the first packet to the neighbors.
In the RFC-4861, the INCOMPLETE state is described as follows (section 7.3.2):
"Address resolution is being performed on the entry. Specifically, a Neighbor
Solicitation has been sent to the solicited-node multicast address of the
target, but the corresponding Neighbor Advertisement has not yet been
received."
But the current LwIP process:
- create a new neighbor entry, init it as INCOMPLETE
- wait for the nd6_tmr timer (once a second)
- nd6_tmr is triggered, send neighbor solicit if the entry's state is
INCOMPLETE
The current process is a little non-conformant with the RFC-4861, the correct
way is to send Neighbor Solicitation immediately for the new neighbor entry,
and then mark it as INCOMPLETE. So there should not be any delay to send the
first Neighbor Discovery which blocks the first packet to the neighbor.
_______________________________________________________
Reply to this item at:
<http://savannah.nongnu.org/bugs/?47652>
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- [lwip-devel] [bug #47652] there is always a delay to send the first Neighbor Solicitation for the new add INCOMPLETE state neighbor entry,
shu chen <=