From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Wed Jan 11 2006 - 14:57:23 GMT-3
Another application of the allowed list would be when you're
doing router-on-a-stick. Since the router IOS does not support VTP
pruning all broadcast and unknown unicast/multicast traffic will be sent
to the router. If you edit the allowed list on the attached switch to
match only the trunked VLANs you cut down on the amount of traffic
forwarded to the router.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> easyman
> Sent: Wednesday, January 11, 2006 4:35 AM
> To: 'Hooman Parta'; 'Victor Cappuccio'; ccielab@groupstudy.com
> Subject: RE: A Jazz at Level 2 in Vlan 1
>
> I think vtp prunning is wiser and more automatic than manually
configure
> "allowed-vlan list" on trunk ports.
> All switches connected via trunk interfaces in the same vtp domain
> maintain
> the same "vtp prunning" status.
> But "allowed-vlan list" on trunk port allow you to do more felxible
> customization of allowd or notallowd vlan-lists.
> Because each trunk interface maintain it's own "allowed-vlan list".
>
>
>
> Regards
> Lin
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Hooman Parta
> Sent: Wednesday, January 11, 2006 11:26 AM
> To: 'Victor Cappuccio'; ccielab@groupstudy.com
> Subject: RE: A Jazz at Level 2 in Vlan 1
>
> Vic,
>
>
> Pruning list is only for VTP protocol not for all of the traffic. So
for
> decreasing of extra traffic on VTP, pruning has been usedas they will
be
> tx/rx on trunks.
>
> Removing VLAN will help to limit ANY traffic (user traffic) of the
VLAN(s)
> on specific trunk as you mentioned.
>
> But for your question why the management traffic, as it mentioned in
the
> document " As a result, no user traffic, including spanning-tree
> advertisements, is sent or received on VLAN 1" CDP,PagP, LACP, DTP,
VTP
> are
> mostly port/switch types of traffic. Personally I think they put STP
for
> security purposes on that category.
>
> My 2 cents
>
> Hooman
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Victor Cappuccio
> Sent: Tuesday, January 10, 2006 5:29 PM
> To: ccielab@groupstudy.com
> Subject: A Jazz at Level 2 in Vlan 1
>
> Hello People..
>
> Please help me to clarify this blur that I have:
>
>
www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12225seb/scg/swvlan.h
tm
> #w
> p1150302
>
> By default, a trunk port sends traffic to and receives traffic from
all
> VLANs. All VLAN IDs, 1 to 4094, are allowed on each trunk.
>
> Switch#show int trunk
> <..>
> Port Vlans allowed on trunk
> Fa0/1 1-4094
> <..>
>
> Switch#show run interface fastEthernet 0/1 Building configuration...
>
> Current configuration : 132 bytes
> !
> interface FastEthernet0/1
> switchport trunk encapsulation dot1q
> switchport trunk allowed vlan 2-4094
> switchport mode trunk
> end
>
> Switch#show int trunk
> <..>
> Port Vlans allowed on trunk
> Fa0/1 2-4094
> <..>
>
> Also says that: To reduce the risk of spanning-tree loops or storms,
you
> can
> disable VLAN 1 on any individual VLAN trunk port by removing VLAN 1
from
> the
> allowed list. This is known as VLAN 1 minimization.
>
> ohh my god this make life a little bit harder.. Is there any hidden
> concept
> here about trunking, Q in Q or something similar?
>
> When you remove VLAN 1 from a trunk port, the interface continues to
send
> and receive management traffic, for example, Cisco Discovery Protocol
> (CDP),
> Port Aggregation Protocol (PAgP), Link Aggregation Control Protocol
> (LACP),
> Dynamic Trunking Protocol (DTP), and VLAN Trunking Protocol (VTP) in
VLAN
> 1.
>
>
> Why Sending then all this Management Traffic??
>
> Now it continues down, to a lot of stuff I could not process :D
>
> But Ok the concept is simple, helps reducing traffic, and increasing
> network
> bandwidth.
>
> But my question is then what is the difference between
Pruning-Eligible
> List
> and removing Traffic from the vlans? Is there something bigger ??
>
> Thanks
> Victor.
>
>
This archive was generated by hypermail 2.1.4 : Wed Feb 01 2006 - 07:45:48 GMT-3