lldpd: implementation of IEEE 802.1ab (LLDP)
============================================
[](http://travis-ci.org/vincentbernat/lldpd)
http://vincentbernat.github.com/lldpd/
Features
--------
LLDP (Link Layer Discovery Protocol) is an industry standard protocol
designed to supplant proprietary Link-Layer protocols such as
Extreme's EDP (Extreme Discovery Protocol) and CDP (Cisco Discovery
Protocol). The goal of LLDP is to provide an inter-vendor compatible
mechanism to deliver Link-Layer notifications to adjacent network
devices.
lldpd implements both reception and sending. It also implements an
SNMP subagent for net-snmp to get local and remote LLDP
information. The LLDP MIB is partially implemented but the most useful
tables are here. lldpd also partially implements LLDP-MED.
lldpd supports bridge, vlan and bonding. bonding need to be done on
real physical devices, not on bridges, vlans, etc. However, vlans can
be mapped on the bonding device. You can bridge vlan but not add vlans
on bridges. More complex setups may give false results.
The following OS are supported:
* FreeBSD
* GNU/Linux
* NetBSD
* OpenBSD
* Mac OS X
Installation
------------
To compile lldpd, use the following:
./configure
make
sudo make install
You need libevent that you can grab from http://libevent.org or
install from your package system (libevent-dev for Debian/Ubuntu and
libevent-devel for Redhat/Fedora/CentOS/SuSE).
If your system does not have libevent, ./configure will use the
shipped copy and compile it statically.
If it complains about a missing agent/struct.h, your installation of
Net-SNMP is incomplete. The easiest way to fix this is to provide an
empty struct.h:
touch src/struct.h
lldpd uses privilege separation to increase its security. Two
processes, one running as root and doing minimal stuff and the other
running as an unprivileged user into a chroot doing most of the stuff,
are cooperating. You need to create a user called `_lldpd` in a group
`_lldpd` (this can be change with `./configure`). You also need to
create an empty directory `/var/run/lldpd` (it needs to be owned by
root, not `_lldpd`!). If you get fuzzy timestamps from syslog, copy
`/etc/locatime` into the chroot.
`lldpcli` lets one query information collected through the command
line. If you don't want to run it as root, just install it setuid or
setgid `_lldpd`.
Installation (Mac OS X)
-----------------------
The same procedure as above applies for Mac OS X. However, there are
simpler alternatives:
1. Use [Homebrew](http://mxcl.github.io/homebrew/):
brew install lldpd
# Or, for the latest version:
brew install https://raw.github.com/vincentbernat/lldpd/master/osx/lldpd.rb
2. Build an OSX installer package which should work on the same
version of OS X (it is important to use a separate build
directory):
mkdir build && cd build
../configure --prefix=/usr --sysconfdir=/etc --with-embedded-libevent
make -C osx pkg ARCHS="i386 x86_64"
If you want to compile for an older version of Mac OS X, you need
to find the right SDK and issues commands like those:
SDK=/Developer/SDKs/MacOSX10.6.sdk
mkdir build && cd build
../configure --prefix=/usr --sysconfdir=/etc --with-embedded-libevent \
CFLAGS="-mmacosx-version-min=10.6 -isysroot $SDK" \
LDFLAGS="-mmacosx-version-min=10.6 -isysroot $SDK"
make -C osx pkg ARCHS="i386 x86_64"
If you don't follow the above procedures, you will have to create the
user/group `_lldpd`. Have a look at how this is done in
`osx/scripts/postinstall`.
Usage
-----
lldpd also implements CDP (Cisco Discovery Protocol), FDP (Foundry
Discovery Protocol), SONMP (Nortel Discovery Protocol) and EDP
(Extreme Discovery Protocol). However, recent versions of IOS should
support LLDP and most Extreme stuff support LLDP. When a EDP, CDP or
SONMP frame is received on a given interface, lldpd starts sending
EDP, CDP, FDP or SONMP frame on this interface. Informations collected
through EDP/CDP/FDP/SONMP are integrated with other informations and
can be queried with `lldpcli` or through SNMP.
For bonding, you need 2.6.24 (in previous version, PACKET_ORIGDEV
affected only non multicast packets). See:
* http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=80feaacb8a6400a9540a961b6743c69a5896b937
* http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=8032b46489e50ef8f3992159abd0349b5b8e476c
Otherwise, a packet received on a bond will be affected to all
interfaces of the bond.
On 2.6.27, we are able to receive packets on real interface for bonded
devices. This allows one to get neighbor information on active/backup
bonds. Without the 2.6.27, lldpd won't receive any information on
inactive slaves. Here are the patchs (thanks to Joe Eykholt):
* http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=0d7a3681232f545c6a59f77e60f7667673ef0e93
* http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=cc9bd5cebc0825e0fabc0186ab85806a0891104f
* http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=f982307f22db96201e41540295f24e8dcc10c78f
On FreeBSD, only a recent 9 kernel (9.1 or more recent) will allow to
send LLDP frames on enslaved devices. See this bug report for more
information:
* http://www.freebsd.org/cgi/query-pr.cgi?pr=138620
Some devices (notably Cisco IOS) send frames on the native VLAN while
they should send them untagged. If your network card does not support
accelerated VLAN, you will receive those frames as well. However, if
your network card handles VLAN encapsulation/decapsulation, you need a
recent kernel to be able to receive those frames without listening on
all available VLAN. Starting from Linux 2.6.27, lldpd is able to
capture VLAN frames when VLAN acceleration is supported by the network
card. Here is the patch:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=bc1d0411b804ad190cdadabac48a10067f17b9e6
More information:
* http://en.wikipedia.org/wiki/Link_Layer_Discovery_Protocol
* http://standards.ieee.org/getieee802/download/802.1AB-2005.pdf
* http://wiki.wireshark.org/LinkLayerDiscoveryProtocol
Development
-----------
During development, you may want to execute lldpd at its current
location inside of doing `make install`. The correct way to do this is
to issue the following command:
sudo libtool execute src/daemon/lldpd -L $PWD/src/client/lldpcli -d
You can append any further arguments. If lldpd is unable to find
`lldpcli` it will start in an unconfigured mode and won't send or
accept LLDP frames.
Embedding
---------
To embed lldpd into an existing system, there are two point of entries:
1. If your system does not use standard Linux interface, you can
support additional interfaces by implementing the appropriate
`struct lldpd_ops`. You can look at
`src/daemon/interfaces-linux.c` for examples. Also, have a look at
`interfaces_update()` which is responsible for discovering and
registering interfaces.
2. `lldpcli` provides a convenient way to query `lldpd`. It also
comes with various outputs, including XML which allows one to
parse its output for integration and automation purpose. Another
way is to use SNMP support. A third way is to write your own
controller using `liblldpctl.so`. Its API is described in
`src/lib/lldpctl.h`. The custom binary protocol between
`liblldpctl.so` and `lldpd` is not stable. Therefore, the library
should always be shipped with `lldpd`. On the other hand, programs
using `liblldpctl.so` can rely on the classic ABI rules.
Troubleshooting
---------------
You can use `tcpdump` to look after the packets received and send by
`lldpd`. To look after LLDPU, use:
tcpdump -s0 -vv -pni eth0 ether dst 01:80:c2:00:00:0e
License
-------
lldpd is distributed under the ISC license:
> Permission to use, copy, modify, and/or distribute this software for any
> purpose with or without fee is hereby granted, provided that the above
> copyright notice and this permission notice appear in all copies.
>
> THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
> WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
> MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
> ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
> WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
> ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
> OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
Also, `lldpcli` will be linked to GNU Readline (which is GPL licensed)
if available. To avoid this, use `--without-readline` as a configure
option.