vtp... nooooooooooooooooooo...

for information on vtp click the link below...

http://insearchofthecert.blogspot.com/search/label/vtp

for the record, i don't understand why they insist on teaching this... it should be removed from the platforms altogether...

and an off condition is still not supported... transparent is the only way

for vtpete's sake...

  vtp is vlan trunking protocol, which really has nothing to do with trunking, or anything else... vtp allows for the creation of a vlan management domain that can be password protected and which assists (cough) the administrator in creating vlans (and only vlans) from a server and distributing them to designated clients throughout the domain... wow

  a vtp revision number is the hallmark of the ability to create vlans on clients... a higher number at the server will force the clients to update their vlan.dat files with the freshly minted vlans.  however, if the client has a higher revision number, the update will be ignored... a device in transparent mode will not participate in vtp processing...

  vtp pruning can be used to avoid unnecessary broadcasts to devices connected to trunks that have the intended vlan, but that do not contain any ports.  this is rendered useless by stp which runs an instance for every vlan.  the guidance is to manually prune unnecessary vlans manually, and transparent mode switches are yet unaffected...

so much for vtp...

he-lans...

vlan tagging and 802.1q

802.1q introduced the concept of the native vlan. the native vlan passes untagged frames
and are recognized as belonging to it as such.  other vlans are tagged, thereby
identified, via a two byte tag identifier or TPID which always has a value of 0x8100
(802.1q tag) and another two bytes are used for Tag Control Information (TCI), bringing the total to 4
bytes.  the tci contains a 3 bit priority field (PCP, priority code point) to identify class of service
(COS) and a 12 bit VID (vlan identifier). the single bit remaining and sandwiched between
the pcp and vid is the canonical format identifier (allowing compatibility for ethernet and
token ring). this will be set to 0 for ethernet (if it is set to 1, token ring, you are
working on a network from the last century) I actually supported a token ring network in
the 90's and it was great--back then.

802.1q does not encapsulate the frame although some authors refer to it as such.  it adds
(injects) this two byte field between the source mac and ether type field.  encapsulation
of frames for vlan identification is the purview of that other thing (isl) that cisco
should finally make go away and stop mentioning in cisco press books.

DTP as well as VTP are technologies that also should go away... Are you going to trust your
trunks to discover each other... no... are you going to deploy a new switch without
configuring the proper vlans... no... of course, no... will you save bandwidth and retain
your sanity... yes

even mentioning these things, you can almost see the authors cringing;

    "On critical trunk links in a network, manually configuring the trunking mode on both    
    ends is best so that the link never can be negotiated to any other state."

when is a trunk not critical... good Lord... it's embarrassing...

vtp why?

a switch in your network fails and needs to be replaced... you get a new one next day, what do you do?  take it out of the box, slap a console cable on it, rev it up, configure it with a hostname, give it a default gateway, give it a management vlan and ip address, password protect the vty's and console, assign the vlans and ports as access to those vlans, assign the trunk ports where necessary, manually to trunk mode, copy run start and put it in the closet...  this takes about five minutes...

and what about vtp... turn that shit off...


sw2950_02(config)#int vlan 5
sw2950_02(config-if)#vtp mode off
                     ^
% Invalid input detected at '^' marker.

sw2950_02(config-if)#vtp mode trans
Setting device to VTP TRANSPARENT mode.
sw2950_02(config)#

whoops...
wait, i think i'll create a new vlan today and propagate it across the network from my vtp server.. no...

what if i want to use isl?  don't...

set the access ports to portfast, the trunks to on and stp to rapid-...

so why did i spend all this time learning these things...  so you know to turn that shit off...

vtputt-putt...

normally processing of commands from the CLI happens as soon as you press enter... not so with VTP when creating a vlan... not until you exit will the command process, as seen below...

sw3550_01#debug sw-vlan vtp events
vtp events debugging is on
sw3550_01#term mon
sw3550_01#config t
sw3550_01(config)#vlan 69
sw3550_01(config-vlan)#do sh vlan brie

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/2, Fa0/4, Fa0/5, Fa0/7
                                                Fa0/8, Fa0/9, Fa0/10, Fa0/11
                                                Fa0/12, Fa0/13, Fa0/14, Fa0/15
                                                Fa0/16, Fa0/17, Fa0/18, Fa0/19
                                                Fa0/20, Fa0/22, Fa0/23, Fa0/24
                                                Gi0/1, Gi0/2
23   VLAN0023                         active
1002 fddi-default                     act/unsup
1003 trcrf-default                    act/unsup
1004 fddinet-default                  act/unsup
1005 trbrf-default                    act/unsup

sw3550_01(config-vlan)#exit
sw3550_01(config)#
now we get our debug output
Dec 27 20:10:40.615: VTP LOG RUNTIME: Transmit vtp summary, domain cisco, rev 13
, followers 1, tlv blk size 8 (inc #tlv field),
   MD5 digest calculated = 8D F5 FD E6 E2 18 EB 99 BD AC F8 2F 8B C5 00 DD

Dec 27 20:10:40.615: VTP LOG RUNTIME: Transmit vtp summary, domain cisco, rev 13
, followers 1, tlv blk size 8 (inc #tlv field),
   MD5 digest calculated = 8D F5 FD E6 E2 18 EB 99 BD AC F8 2F 8B C5 00 DD

Dec 27 20:10:40.615: VTP LOG RUNTIME: Transmit vtp summary, domain cisco, rev 13
, followers 1, tlv blk size 8 (inc #tlv field),
   MD5 digest calculated = 8D F5 FD E6 E2 18 EB 99 BD AC F8 2F 8B C5 00 DD

Dec 27 20:10:40.675: VTP LOG RUNTIME: Summary packet received, domain = cisco, r
ev = 13, followers = 1, length 80, trunk Fa0/1

Dec 27 20:10:40.675: VTP LOG RUNTIME: Validate TLVs : #tlvs 1, max blk size 4
Dec 27 20:10:40.675: VTP LOG RUNTIME: Validate TLVs : #00, val 6, len 4
Dec 27 20:10:40.675: VTP LOG RUNTIME: Summary packet rev 13 equal to domain cisc
o rev 13

Dec 27 20:10:40.679: VTP LOG RUNTIME: Subset packet received, domain = cisco, re
v = 13, seq = 1, length = 220

Dec 27 20:10:40.679: VTP LOG RUNTIME: Summary packet received, domain = cisco, r
ev = 13, followers = 1, length 80, trunk Fa0/3

sw3550_01(config)#
Dec 27 20:10:40.679: VTP LOG RUNTIME: Validate TLVs : #tlvs 1, max blk size 4
Dec 27 20:10:40.679: VTP LOG RUNTIME: Validate TLVs : #00, val 6, len 4
Dec 27 20:10:40.679: VTP LOG RUNTIME: Summary packet rev 13 equal to domain cisc
o rev 13

Dec 27 20:10:40.683: VTP LOG RUNTIME: Subset packet received, domain = cisco, re
v = 13, seq = 1, length = 220


sw3550_01(config)#do sh vlan brie
VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/2, Fa0/4, Fa0/5, Fa0/7
                                                Fa0/8, Fa0/9, Fa0/10, Fa0/11
                                                Fa0/12, Fa0/13, Fa0/14, Fa0/15
                                                Fa0/16, Fa0/17, Fa0/18, Fa0/19
                                                Fa0/20, Fa0/22, Fa0/23, Fa0/24
                                                Gi0/1, Gi0/2
23   VLAN0023                         active
69   VLAN0069                         active1002 fddi-default                     act/unsup
1003 trcrf-default                    act/unsup
1004 fddinet-default                  act/unsup
1005 trbrf-default                    act/unsup
sw3550_01(config)#


so much for command processing love...

debug vtp...

s3(config)#do sh vlan
VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/3, Fa0/4, Fa0/5
10   fac/staff                        active    Fa0/11, Fa0/12, Fa0/13, Fa0/14
                                                Fa0/15, Fa0/16, Fa0/17
20   students                         active    Fa0/18, Fa0/19, Fa0/20, Fa0/21
                                                Fa0/22, Fa0/23, Fa0/24
30   guest                            active    Fa0/6, Fa0/7, Fa0/8, Fa0/9
                                                Fa0/10
99   mgmt&native                      active

s3#debug sw-vlan vtp ?
  events   vtp events
  packets  vtp packets
  pruning  vtp pruning events
  xmit     vtp packets transmitted
s3#debug sw-vlan vtp events
vtp events debugging is on
s3#
01:41:21: VTP LOG RUNTIME: Summary packet received, domain = ozlan, rev = 56, fo
llowers = 1, length 80, trunk Fa0/2

01:41:21: VTP LOG RUNTIME: Validate TLVs : #tlvs 1, max blk size 4
01:41:21: VTP LOG RUNTIME: Validate TLVs : #00, val 6, len 4
Summary packet rev 56 greater than domain ozlan rev 5
5
s3#sh vlan
01:41:21: VTP LOG RUNTIME:

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/3, Fa0/4, Fa0/5
10   fac/staff                        active    Fa0/11, Fa0/12, Fa0/13, Fa0/14
                                                Fa0/15, Fa0/16, Fa0/17
20   students                         active    Fa0/18, Fa0/19, Fa0/20, Fa0/21
                                                Fa0/22, Fa0/23, Fa0/24
30   guest                            active    Fa0/6, Fa0/7, Fa0/8, Fa0/9
                                                Fa0/10
69   VLAN0069                         active
99   mgmt&native                      active

vlan creation myth...

actual cert question from reputable (nameless) cert type authority...

which of the following steps are necessary to add a new vlan to a switched network
select all that apply

a) create vlan
b) name vlan
c) configure ip address for vlan
d) add desired ports to vlan
e) add vlan to vtp domain

given answer a,b,d

WRONG...  read the question... necessary to add a new vlan
only a) is correct... of course it's pretty useless without the other stuff, but that wasn't the question... see below...

sw3550_01(config)#vlan 69
sw3550_01(config-vlan)#end
sw3550_01#sh vlan

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1, Fa0/2, Fa0/3, Fa0/4
                                                Fa0/5, Fa0/6, Fa0/7, Fa0/8
                                                Fa0/9, Fa0/10, Fa0/11, Fa0/12
                                                Fa0/13, Fa0/14, Fa0/15, Fa0/16
                                                Fa0/17, Fa0/18, Fa0/19, Fa0/20
                                                Fa0/22, Gi0/1, Gi0/2
2    hosts                            active
10   10                               active
69   VLAN0069                         active

note that the only requirement to CREATE a vlan is:

sw3550_01(config)#vlan 69

the others are options; the name is plugged in by default, added ports are not necessary, and the new vlan is automatically activated...

from the horse's mouth...
http://www.ciscopress.com/articles/article.asp?p=29803

VLANs are created by number, and there are two ranges of usable VLAN numbers (normal range 1–1000 and extended range 1025–4096). When a VLAN is created, you can also give it certain attributes such as a VLAN name, VLAN type, and its operational state.

be very afraid...

saran wrap...

when you receive a cisco switch it is by default set to server mode out of the box...  be sure to set it to transparent mode before deployment...

Server
 can create, add, delete  and/or change vlan information.  these changes are added throughout the VTP domain

Client
  listen for advertisements and modify their own configurations as a result.  a server is required by the client    for vlan changes. a client cannot create, add or delete vlans

Transparent
  can forward or receive vlan advertisements but otherwise do not participate in the domain...

you can see right through them... so there...

some network output...

i'm starting out with rip, then eigrp and ospf... you can see below how it's shaping up... still have many things to do, vlan and interface descriptions, ios upgrades, serial connections, trunking, stp, vtp, etc... i'd like to say i'm having fun, but it's gone from a treat to an obsession... vpn, firewall, sdm, frame... damn...

sw3550#sh cdp neigh
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
r2620_03         Fas 0/18           148           R       2620XM    Fas 0/0
r2620_02         Fas 0/8            123         R S I     Cisco 2620Fas 0/0
r2620_01         Fas 0/1            176           R       2620XM    Fas 0/0
sw3550#

sw3550#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
       * - candidate default, U - per-user static route, o - ODR
       P - periodic downloaded static route

Gateway of last resort is not set

R    1.0.0.0/8 [120/1] via 192.168.1.100, 00:00:07, Vlan1
R    2.0.0.0/8 [120/1] via 10.0.0.2, 00:00:21, Vlan2
C    100.0.0.0/8 is directly connected, Loopback0
R    3.0.0.0/8 [120/1] via 172.16.0.2, 00:00:14, Vlan3
C    172.16.0.0/16 is directly connected, Vlan3
     10.0.0.0/24 is subnetted, 1 subnets
C       10.0.0.0 is directly connected, Vlan2
C    192.168.1.0/24 is directly connected, Vlan1
sw3550#

as an old college friend of mine used to say:

may the bulls run wild...