Bug 213804 - [carp]: packets got processes on the BACKUP node under certain conditions
Summary: [carp]: packets got processes on the BACKUP node under certain conditions
Status: New
Alias: None
Product: Base System
Classification: Unclassified
Component: kern (show other bugs)
Version: 10.3-STABLE
Hardware: Any Any
: --- Affects Only Me
Assignee: freebsd-net mailing list
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2016-10-26 11:58 UTC by emz
Modified: 2016-10-26 22:44 UTC (History)
0 users

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Description emz 2016-10-26 11:58:52 UTC
Consider the following scheme:

  
          +-----------------+
   iface1 |                 | iface2
  +-------| host A (MASTER) |--------
  |       |                 |
  |       +-----------------+
carp1
  |       +-----------------+
  |       |                 |  iface2
  +-------| host B (BACKUP) |--------  << packet to carp 1 IP
   iface1 |                 |
          +-----------------+

Lets assume both hosts are advertising themselves using rtadvd as ipv6 routers for network attached to the iface2. In this case, they both can receive ipv6 packets undercertain conditions, destined to the CARP address carp1. When a BACKUP node receives such packets, it processes them locally, regardless of the state of the CARP, as if it was MASTER.

I observe this only on the ipv6, because the process of router advertising in ipv6 is different from ipv4. However, I suppose the same rule applies to the ipv4, but it's not that important, since I cannot imagine the configuration that would reproduce this for ipv4.