CDP CACHE ENTRIES

NAME

SNMP::Info::CDP - Perl5 Interface to Cisco Discovery Protocol (CDP) using SNMP

AUTHOR

Max Baker (max@warped.org)

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 $c_if       = $cdp->c_if();
 my $c_ip       = $cdp->c_ip();
 my $c_port     = $cdp->c_port();

 foreach my $cdp_key (keys %$c_ip){
    my $iid           = $c_if->{$cdp_key};
    my $port          = $interfaces->{$iid};
    my $neighbor      = $c_ip->{$cdp_key};
    my $neighbor_port = $c_port->{$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_id(): 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->c_capabilities()

Returns Device Functional Capabilities. Results are munged into an ascii binary string, 7 digits long, MSB. Each digit represents a bit from the table below.

From http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/frames.htm#18843:

(Bit) - Description

(0x40) - Provides level 1 functionality.
(0x20) - The bridge or switch does not forward IGMP Report packets on nonrouter 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 martin -at- lorensen.dk for a pointer to this information.

(cdpCacheCapabilities)

$cdp->c_domain()

Returns remote VTP Management Domain as defined in CISCO-VTP-MIB::managementDomainName

(cdpCacheVTPMgmtDomain)

$cdp->c_duplex()

Returns the port duplex status from remote devices.

(cdpCacheDuplex)

$cdp->c_id()

Returns remote device id string

(cdpCacheDeviceId)

$cdp->c_if()

Returns the mapping to the SNMP Interface Table.

Note that a lot devices don't implement $cdp->c_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 $c_index     = $device->c_index();
  return $c_index if defined $c_index;

  # if not, let's fake it
  my $c_ip       = $device->c_ip();
    
  my %c_if
  foreach my $key (keys %$c_ip){
      $iid = $key;
      ## Truncate off .1 from cdp response
      $iid =~ s/\.\d+$//;
      $c_if{$key} = $iid;
  }
 
  return \%c_if;

$cdp->c_index()