Re: CDP if IP

[Bill Meier <wmeier () newsguy com>]

On 6/26/2011 11:45 PM, Jesper Gjesager Thusgaard wrote:
> Hi
>
> I'm new at wireshark.
> Is it possible to make a filter that only shows CDP information, if an IP is
> offered.

I'm assuming you are referring to CDP as in 'Cisco Discovery Protocol'.

Do you mean by 'If an IP is offered' that a CDP message contains an 
"ADDRESS" TLV ?  If so, then the following display filter should work.

  cdp.tlv.type == 2


Is this the info you need ?

Note:

The values for the various TLV types (from the dissector source):

#define TYPE_DEVICE_ID          0x0001
#define TYPE_ADDRESS            0x0002
#define TYPE_PORT_ID            0x0003
#define TYPE_CAPABILITIES       0x0004
#define TYPE_IOS_VERSION        0x0005
#define TYPE_PLATFORM           0x0006
#define TYPE_IP_PREFIX          0x0007
#define TYPE_PROTOCOL_HELLO     0x0008 /* Protocol Hello */
#define TYPE_VTP_MGMT_DOMAIN    0x0009 /* VTP Domain, CTPv2 - see second 
URL */
#define TYPE_NATIVE_VLAN        0x000a /* Native VLAN, CTPv2 - see 
second URL */
#define TYPE_DUPLEX             0x000b /* Full/Half Duplex - see second 
URL */
/*                              0x000c */
/*                              0x000d */
#define TYPE_VOIP_VLAN_REPLY    0x000e /* VoIP VLAN reply */
#define TYPE_VOIP_VLAN_QUERY    0x000f /* VoIP VLAN query */
#define TYPE_POWER              0x0010 /* Power consumption */
#define TYPE_MTU                0x0011 /* MTU */
#define TYPE_TRUST_BITMAP       0x0012 /* Trust bitmap */
#define TYPE_UNTRUSTED_COS      0x0013 /* Untrusted port CoS */
#define TYPE_SYSTEM_NAME        0x0014 /* System Name */
#define TYPE_SYSTEM_OID         0x0015 /* System OID */
#define TYPE_MANAGEMENT_ADDR    0x0016 /* Management Address(es) */
#define TYPE_LOCATION           0x0017 /* Location */
#define TYPE_EXT_PORT_ID        0x0018 /* External Port-ID */
#define TYPE_POWER_REQUESTED    0x0019 /* Power Requested */
#define TYPE_POWER_AVAILABLE    0x001a /* Power Available */
#define TYPE_PORT_UNIDIR        0x001b /* Port Unidirectional */
#define TYPE_NRGYZ              0x001d /* EnergyWise over CDP */
#define TYPE_SPARE_POE          0x001f /* Spare Pair PoE */
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