From: Mounir Mohamed (mounir.mohamed@gmail.com)
Date: Wed Jul 25 2007 - 15:28:32 ART
Does anyboy know which method used by the switches to advertise thier active
VLANs and re-advertise for delete or added VLANs!!!
(CDP frames or VTP messages or !!!
On 7/25/07, Victor Cappuccio <vcappuccio@ccbootcamp.com> wrote:
>
> Hi Ajay,
>
> http://en.wikipedia.org/wiki/VTP#VLAN_Pruning
>
> VTP can prune unneeded VLANs from trunk links. VTP maintains a map of
> VLANs
> and switches, enabling traffic to be directed only to those switches known
> to
> have ports on the intended VLAN. This enables more efficient use of trunk
> bandwidth.
>
> Each switch will advertise which VLAN's it has active to neighboring
> switches.
> The neighboring switches will then "prune" VLAN's that are not active
> across
> that trunk, thus saving bandwidth. If a VLAN is then added to one of the
> switches, the switch will then re-advertise it's active VLAN's so that
> pruning
> can be updated by its neighbors. For this to work, VLAN pruning must be
> enabled on both ends of the trunk. It is easiest to enable VLAN pruning
> for an
> entire VTP management domain by simply enabling it on one of the VTP
> servers
> for that domain. To enable VLAN pruning for a VTP domain, enter the
> following
> command on a VTP server for that domain...
>
> VTP_Server_Sw1(config)# vtp pruning
>
> This will then propagate to all switches in the vtp domain.
>
>
> Couple of good links:
>
> http://www.cisco.com/warp/public/473/21.html <-- far way good peace of
> document (with swf included :D)
>
> www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/rel_4_2/config/vlans.htm
> www.ciscopress.com/articles/article.asp?p=29803&seqNum=4
>
> Having this topology
>
> sw1 Sw2
> | |
> Sw3 - Sw4
>
> Sw3#conf ter
> Enter configuration commands, one per line. End with CNTL/Z.
> Sw3(config)#vtp pruning
> Cannot modify pruning unless in VTP server mode
> Sw3(config)#do show vtp Mode
> Sw3(config)#do show vtp status | in Mode
> VTP Operating Mode : Client
> VTP Pruning Mode : Disabled
> VTP V2 Mode : Disabled
> Sw3(config)#
>
> The configuration of trunk links (using protocols like ISL or .1q ) allows
> traffic from multiple VLANs to travel across this links, this is not
> always
> optimal
>
> Sw3(config)#do show int trunk
>
> Port Mode Encapsulation Status Native vlan
> Fa0/19 on 802.1q trunking 1
> Fa0/20 on 802.1q trunking 1
> Fa0/21 on 802.1q trunking 1
> Fa0/22 on 802.1q trunking 1
>
> Port Vlans allowed on trunk
> Fa0/19 1-4094
> Fa0/20 1-4094
> Fa0/21 1-4094
> Fa0/22 1-4094
>
> Port Vlans allowed and active in management domain
> Fa0/19 1,12,100,104,106,149,156,237,735
> Fa0/20 1,12,100,104,106,149,156,237,735
> Fa0/21 1,12,100,104,106,149,156,237,735
> Fa0/22 1,12,100,104,106,149,156,237,735
> ---------------------------------------------------> All Traffic for the
> different vlans pass over the trunk by default
> Port Vlans in spanning tree forwarding state and not pruned
> Fa0/19 1,12,100,104,106,149,156,237,735
> Fa0/20 1,12,100,104,106,149,156,237,735
> Fa0/21 1,12,100,104,106,149,156,237,735
>
> Port Vlans in spanning tree forwarding state and not pruned
> Fa0/22 none
>
>
>
> Sw3(config)#do show 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, Fa0/23,
> Fa0/24
> Gi0/1, Gi0/2
> 12 VLAN0012 active
> 100 VLAN0100 active
> 104 VLAN0104 active
> 106 VLAN0106 active
> 149 VLAN0149 active
> 156 VLAN0156 active
> 237 VLAN0237 active
> 735 VLAN0735 active
> 1002 fddi-default act/unsup
> 1003 token-ring-default act/unsup
> 1004 fddinet-default act/unsup
> 1005 trnet-default act/unsup
>
> VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1
> Trans2
> ---- ----- ---------- ----- ------ ------ -------- ---- -------- ------
> ------
> 1 enet 100001 1500 - - - - - 0 0
> 12 enet 100012 1500 - - - - - 0 0
> 100 enet 100100 1500 - - - - - 0 0
> 104 enet 100104 1500 - - - - - 0 0
> 106 enet 100106 1500 - - - - - 0 0
> 149 enet 100149 1500 - - - - - 0 0
> 156 enet 100156 1500 - - - - - 0 0
> 237 enet 100237 1500 - - - - - 0 0
> 735 enet 100735 1500 - - - - - 0 0
> 1002 fddi 101002 1500 - - - - - 0 0
> 1003 tr 101003 1500 - - - - srb 0 0
> 1004 fdnet 101004 1500 - - - ieee - 0 0
> 1005 trnet 101005 1500 - - - ibm - 0 0
>
> Remote SPAN VLANs
>
> -----------------------------------------------------------------------------
> -
>
>
> Primary Secondary Type Ports
> ------- --------- -----------------
> ------------------------------------------
>
> Sw3(config)#
>
>
> if we enable prunning in our network
>
> Sw1(config)#vtp prun
> Pruning switched on
>
> then we have a different result
> Sw3(config)#do show int trunk
>
> Port Mode Encapsulation Status Native vlan
> Fa0/19 on 802.1q trunking 1
> Fa0/20 on 802.1q trunking 1
> Fa0/21 on 802.1q trunking 1
> Fa0/22 on 802.1q trunking 1
>
> Port Vlans allowed on trunk
> Fa0/19 1-4094
> Fa0/20 1-4094
> Fa0/21 1-4094
> Fa0/22 1-4094
>
> Port Vlans allowed and active in management domain
> Fa0/19 1,12,100,104,106,149,156,237,735
> Fa0/20 1,12,100,104,106,149,156,237,735
> Fa0/21 1,12,100,104,106,149,156,237,735
> Fa0/22 1,12,100,104,106,149,156,237,735
> --------------------------------------------------------------------> now
> the
> traffic get allocated in the best path to send the Unknown traffic /
> Multicast-Broadcast
> Port Vlans in spanning tree forwarding state and not pruned
> Fa0/19 1,104,237
> Fa0/20 1
> Fa0/21 1,12,100,104,149,156,237,735
>
> Port Vlans in spanning tree forwarding state and not pruned
> Fa0/22 none
> Sw3(config)#
>
> now lets create a new vlan in Sw1 (VTP Server of this domain) and lets
> assign
> that to a port in Sw3
>
> Sw1(config)#vlan 13
> Sw1(config-vlan)#exit
> Sw1(config)#do show int trunk
>
> Port Mode Encapsulation Status Native vlan
> Fa0/19 on 802.1q trunking 1
> Fa0/20 on 802.1q trunking 1
> Fa0/21 on 802.1q trunking 1
> Fa0/22 on 802.1q trunking 1
>
> Port Vlans allowed on trunk
> Fa0/19 1-4094
> Fa0/20 1-4094
> Fa0/21 1-4094
> Fa0/22 1-4094
>
> Port Vlans allowed and active in management domain
> Fa0/19 1,12-13,100,104,106,149,156,237,735 -------------------->
> Vlan
> 13 here
> Fa0/20 1,12-13,100,104,106,149,156,237,735
> Fa0/21 1,12-13,100,104,106,149,156,237,735
> Fa0/22 1,12-13,100,104,106,149,156,237,735
>
> ---------------------------------------------------------------------->
> but
> V13 is not down here.
> Port Vlans in spanning tree forwarding state and not pruned
> Fa0/19 1,12,104,149,156,237,735
> Fa0/20 1
> Fa0/21 1,104,149,237
>
> Port Vlans in spanning tree forwarding state and not pruned
> Fa0/22 1
> Sw1(config)#
>
> Now lets assign that Vlan to a couple of ports int sw1 -to- sw4
>
> Sw1(config-if)#int f0/5
> Sw1(config-if)#sw a vlan 13
> Sw1(config-if)#exit
> Sw1(config)#do show int trunk
>
> Port Mode Encapsulation Status Native vlan
> Fa0/19 on 802.1q trunking 1
> Fa0/20 on 802.1q trunking 1
> Fa0/21 on 802.1q trunking 1
> Fa0/22 on 802.1q trunking 1
>
> Port Vlans allowed on trunk
> Fa0/19 1-4094
> Fa0/20 1-4094
> Fa0/21 1-4094
> Fa0/22 1-4094
>
> Port Vlans allowed and active in management domain
> Fa0/19 1,12-13,100,104,106,149,156,237,735
> Fa0/20 1,12-13,100,104,106,149,156,237,735
> Fa0/21 1,12-13,100,104,106,149,156,237,735
> Fa0/22 1,12-13,100,104,106,149,156,237,735
>
> Port Vlans in spanning tree forwarding state and not pruned
> Fa0/19 1,12,104,149,156,237,735
> Fa0/20 1
> Fa0/21 1,104,149,237
>
> Port Vlans in spanning tree forwarding state and not pruned
> Fa0/22 1
>
>
> Sw3(config)#int f0/7
> Sw3(config-if)#sw host
> switchport mode will be set to access
> spanning-tree portfast will be enabled
> channel group will be disabled
>
> Sw3(config-if)#sw a vlan 13
> Sw3(config-if)#no sh
> Sw3(config-if)#do show vlan id 13
>
> VLAN Name Status Ports
> ---- -------------------------------- ---------
> -------------------------------
> 13 VLAN0013 active Fa0/7, Fa0/19, Fa0/20,
> Fa0/21
> Fa0/22
>
> VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1
> Trans2
> ---- ----- ---------- ----- ------ ------ -------- ---- -------- ------
> ------
> 13 enet 100013 1500 - - - - - 0 0
>
> Remote SPAN VLAN
> ----------------
> Disabled
>
> Primary Secondary Type Ports
> ------- --------- -----------------
> ------------------------------------------
> Sw3(config-if)#do show int trunk
>
> Port Mode Encapsulation Status Native vlan
> Fa0/19 on 802.1q trunking 1
> Fa0/20 on 802.1q trunking 1
> Fa0/21 on 802.1q trunking 1
> Fa0/22 on 802.1q trunking 1
>
> Port Vlans allowed on trunk
> Fa0/19 1-4094
> Fa0/20 1-4094
> Fa0/21 1-4094
> Fa0/22 1-4094
>
> Port Vlans allowed and active in management domain
> Fa0/19 1,12-13,100,104,106,149,156,237,735
> Fa0/20 1,12-13,100,104,106,149,156,237,735
> Fa0/21 1,12-13,100,104,106,149,156,237,735
> Fa0/22 1,12-13,100,104,106,149,156,237,735
>
> -------------------------------------------------------------------> now
> vlan
> 13 traffic is send out port f0/21 for unknown/multicast traffic
>
> Port Vlans in spanning tree forwarding state and not pruned
> Fa0/19 1,104,237
> Fa0/20 1
> Fa0/21 1,12-13,100,104,149,156,237,735
>
> Port Vlans in spanning tree forwarding state and not pruned
> Fa0/22 none
> Sw3(config-if)#
>
> When VTP Pruning is implemented in a VTP management domain, traffic for a
> given VLAN is only passed to a switch across a trunk link if necessary
>
> HTH
>
> thanks,
> Victor Cappuccio.-
> - CCSI# 31452
>
> Network Learning Inc - A Cisco Sponsored Organization (SO) YES! We take
> Cisco Learning credits!
> vcappuccio@ccbootcamp.com
> http://www.ccbootcamp.com (Cisco Training and Rental Racks)
> Voice: 702-968-5100
> FAX: 702-446-8012
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com on behalf of Ajay Prakash
> Sent: Wed 25-Jul-07 2:13 AM
> To: Cisco certification
> Cc: Ajay Prakash
> Subject: VTP Pruning
>
> Hello,
>
> I have a query regarding VTP pruning.
>
> ____________________________ SW2
> |
> |
> SW1--------------------------------------------- SW3
> |
> |____________________________ SW4
>
>
> SW1 has trunk links to SW2, SW3 and SW4. We want the switches to prune
> vlans
> for which they do not have any ports assigned and the requirement tells us
> to
> do it in minimum number of commands (IE lab 2)
>
> I had enabled VTP pruning on all 4 switches but when I checked the
> solution
> in
> the workbook, they have enabled pruning just on SW1. My understanding was
> that
> if a switch does not use a vlan, it sends the prune message and hence it
> should be configured on all 4 switched.
>
> Any inputs regarding this would be greatly appreciated.
>
> Regards,
> Ajay Prakash
>
> _______________________________________________________________________
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-- Best Reagrds, Mounir Mohamed
This archive was generated by hypermail 2.1.4 : Sat Aug 18 2007 - 08:17:42 ART