SNMP::Info::CDP(3) SNMP Interface to Cisco Discovery Protocol (CDP) using SNMP

AUTHOR

Max Baker

SYNOPSIS


my $cdp = new SNMP::Info (
AutoSpecify => 1,
Debug => 1,
DestHost => 'router',
Community => 'public',
Version => 2
);
my $class = $cdp->class();
print " Using device sub class : $class\n";
$hascdp = $cdp->hasCDP() ? 'yes' : 'no';
# Print out a map of device ports with CDP neighbors:
my $interfaces = $cdp->interfaces();
my $cdp_if = $cdp->cdp_if();
my $cdp_ip = $cdp->cdp_ip();
my $cdp_port = $cdp->cdp_port();
foreach my $cdp_key (keys %$cdp_ip){
my $iid = $cdp_if->{$cdp_key};
my $port = $interfaces->{$iid};
my $neighbor = $cdp_ip->{$cdp_key};
my $neighbor_port = $cdp_port->{$cdp_key};
print "Port : $port connected to $neighbor / $neighbor_port\n";
}

DESCRIPTION

SNMP::Info::CDP is a subclass of SNMP::Info that provides an object oriented interface to CDP information through SNMP.

CDP is a Layer 2 protocol that supplies topology information of devices that also speak CDP, mostly switches and routers. CDP is implemented in Cisco and some HP devices.

Create or use a device subclass that inherits this class. Do not use directly.

Each device implements a subset of the global and cache entries. Check the return value to see if that data is held by the device.

Inherited Classes

None.

Required MIBs

CISCO-CDP-MIB

MIBs can be found at ftp://ftp.cisco.com/pub/mibs/v2/v2.tar.gz

GLOBAL METHODS

These are methods that return scalar values from SNMP
$cdp->hasCDP()
Is CDP is active in this device?

Accounts for SNMP version 1 devices which may have CDP but not cdp_run()

$cdp->cdp_run()
Is CDP enabled on this device? Note that a lot of Cisco devices that implement CDP don't implement this value. @#%$!

("cdpGlobalRun")

$cdp->cdp_interval()
Interval in seconds at which CDP messages are generated.

("cdpGlobalMessageInterval")

$cdp->cdp_holdtime()
Time in seconds that CDP messages are kept.

("cdpGlobalHoldTime")

$cdp->cdp_gid()
Returns CDP device ID.

This is the device id broadcast via CDP to other devices, and is what is retrieved from remote devices with $cdp->id().

("cdpGlobalDeviceId")

TABLE METHODS

These are methods that return tables of information in the form of a reference to a hash.

CDP CACHE ENTRIES

$cdp->cdp_capabilities()
Returns Device Functional Capabilities. Results are munged into an ascii binary string, MSB. Each digit represents a bit from the table below from the CDP Capabilities Mapping to Smartport Type table within the Cisco Small Business 200 Series Smart Switch Administration Guide, <http://www.cisco.com/c/en/us/support/switches/small-business-200-series-smart-switches/products-maintenance-guides-list.html>:

(Bit) - Description

(0x400) - Two-Port MAC Relay.
(0x200) - CAST Phone Port / CVTA / Supports-STP-Dispute depending upon platform.
(0x100) - Remotely-Managed Device.
(0x80) - VoIP Phone.
(0x40) - Provides level 1 functionality.
(0x20) - The bridge or switch does not forward IGMP Report packets on non router ports.
(0x10) - Sends and receives packets for at least one network layer protocol. If the device is routing the protocol, this bit should not be set.
(0x08) - Performs level 2 switching. The difference between this bit and bit 0x02 is that a switch does not run the Spanning-Tree Protocol. This device is assumed to be deployed in a physical loop-free topology.
(0x04) - Performs level 2 source-route bridging. A source-route bridge would set both this bit and bit 0x02.
(0x02) - Performs level 2 transparent bridging.
(0x01) - Performs level 3 routing for at least one network layer protocol.

Thanks to Martin Lorensen for a pointer to the original information and CPAN user Alex for updates.

("cdpCacheCapabilities")

$cdp->cdp_domain()
Returns remote VTP Management Domain as defined in "CISCO-VTP-MIB::managementDomainName"

("cdpCacheVTPMgmtDomain")

$cdp->cdp_duplex()
Returns the port duplex status from remote devices.

("cdpCacheDuplex")

$cdp->cdp_id()
Returns remote device id string

("cdpCacheDeviceId")

$cdp->cdp_if()
Returns the mapping to the SNMP Interface Table.

Note that a lot devices don't implement $cdp->cdp_index(), So if it isn't around, we fake it.

In order to map the cdp table entry back to the interfaces() entry, we truncate the last number off of it : 

  # it exists, yay.
  my $cdp_index     = $device->cdp_index();
  return $cdp_index if defined $cdp_index;
  # if not, let's fake it
  my $cdp_ip       = $device->cdp_ip();
    
  my %cdp_if
  foreach my $key (keys %$cdp_ip){
      $iid = $key;
      ## Truncate off .1 from cdp response
      $iid =~ s/\.\d+$//;
      $cdp_if{$key} = $iid;
  }
 
  return \%cdp_if;
$cdp->cdp_index()
Returns the mapping to the SNMP2 Interface table for CDP Cache Entries.

Most devices don't implement this, so you probably want to use $cdp->cdp_if() instead.

See cdp_if() entry.

("cdpCacheIfIndex")

$cdp->cdp_ip()
If $cdp->cdp_proto() is supported, returns remote IPV4 address only. Otherwise it will return all addresses.

("cdpCacheAddress")

$cdp->cdp_addr()
Returns remote address

("cdpCacheAddress")

$cdp->cdp_platform()
Returns remote platform id

("cdpCachePlatform")

$cdp->cdp_port()
Returns remote port ID

("cdpDevicePort")

$cdp->cdp_proto()
Returns remote address type received. Usually IP.

("cdpCacheAddressType")

$cdp->cdp_ver()
Returns remote hardware version

("cdpCacheVersion")

$cdp->cdp_vlan()
Returns the remote interface native VLAN.

("cdpCacheNativeVLAN")

$cdp->cdp_power()
Returns the amount of power consumed by remote device in milliwatts munged for decimal placement.

("cdpCachePowerConsumption")

$cdp->cdp_cap()
Returns hash of arrays with each array containing the system capabilities supported by the remote system. Possible elements in the array are "Router", "Trans-Bridge", "Source-Route-Bridge", "Switch", "Host", "IGMP", "Repeater", "VoIP-Phone", "Remotely-Managed-Device", "Supports-STP-Dispute", and "Two-port Mac Relay".

Data Munging Callback Subroutines

$cdp->munge_power()
Inserts a decimal at the proper location.

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