10-15-2009 05:34 PM - edited 03-06-2019 08:09 AM
I see a lot of paper talking about using layer3 switching + routing instead of spanning tree.
I would like to know in cisco enviroment, (cisco catalyst switchs/router) is there any benefit to stop using spanning tree?
Does anyone do using layer3 switching only in large network?
Any comments will be appreciated
Thanks in advance
Solved! Go to Solution.
10-15-2009 07:10 PM
Either design has its pros and cons and you must understand the implications when choosing one over the other.
On a routed inter-switch design - you lose the ability to dual home servers so this design may not work in a server farm. If you routed to the access switch, workstations may get a different subnet depending on the switch they are connecting. Take into account larger DHCP scope and more subnets.
On a routed inter-switch design - you limit your L2 domain to a single switch. You have a faster convergence and L2 loops are non-existence.
I know many large companies using both designs and both work quite well depending upon the requirements.
Regards,
Edison.
10-16-2009 01:35 AM
Hello Julie,
sorry for misunderstanding I should have thought it coould be just a typing error!
Cisco devices default to PVST+ that is proprietary and can interact with legacy 802.1D on a per port basis.
In a multi-vendor environment if all devices support it 802.1s MST can be used.
It requires more management efforts because configuration of
MST region name
MST revision number
mapping of Vlans to MST instances
need to match and need to be configured manually.
MST requires a change of mind that is you are encouraged to plan : that is you can divide the 4094 possible vlans in 64 subsets and you can associate them each subset to a different MST instance.
in this way you just need to choice a vlan from a subset and to create it on devices and you get a zero touch MST campus (that is you don't need to modify all those parameters that cause temporary problems as reported by other users).
the advantage is that the vlans don't need to already exist they can mapped before.
For a multivendor environment MST should be the best choice because it allows to build multiple topologies (one for each MST instance) and it is more scalable then Cisco PVST+ or Rapid PVST (it uses an instance for each vlan to be considered low end cisco switches have limits that can be reached in a campus)
Hope to help
Giuseppe
10-16-2009 04:58 AM
if I want implement VoIP and multi-media sulotion, on basic routing/switching site, what improvement I need consider?
QoS
You want to make sure you prioritize VoIP traffic and guarantee bandwidth for mission-critical applications such as Video.
Regards
Edison.
10-16-2009 08:44 AM
Hello Julie,
Rapid STP is recommended for VoIP applications
and QoS is very important as Edison has noted.
Hope to help
Giuseppe
10-15-2009 07:10 PM
Either design has its pros and cons and you must understand the implications when choosing one over the other.
On a routed inter-switch design - you lose the ability to dual home servers so this design may not work in a server farm. If you routed to the access switch, workstations may get a different subnet depending on the switch they are connecting. Take into account larger DHCP scope and more subnets.
On a routed inter-switch design - you limit your L2 domain to a single switch. You have a faster convergence and L2 loops are non-existence.
I know many large companies using both designs and both work quite well depending upon the requirements.
Regards,
Edison.
10-15-2009 07:16 PM
Edison
great thanks for the clarify, one more question, I hear someone said the spanning tree require all the equipment in the domain are unix product, is it true?
Please advice
10-16-2009 12:18 AM
Hello Julie,
>> I hear someone said the spanning tree require all the equipment in the domain are unix product, is it true?
I've never heard of this.
it is not true.
STP manages OSI Layer2 redundancy, unix is a flavor of operating system on workstations.
no direct relation between the two.
old unix workstations may have specific requirements for OSI L3:
use of RIP
or need of proxy-ARP enabled on routers because they could use the major network mask and not the correct subnet mask.
Hope to help
Giuseppe
10-16-2009 01:13 AM
sorry, Giuseppe
I wrote by mistake, can I repeat question again.
I heard spanning-tree require all the equipment in the domain with same product, for example, if I use cisco switches, I have to use cisco switches all the time, if I want mix with to other switchs, I will have protential problem.
Is it a right statement? Please advice.
Thanks in advance
Julie
10-16-2009 01:35 AM
Hello Julie,
sorry for misunderstanding I should have thought it coould be just a typing error!
Cisco devices default to PVST+ that is proprietary and can interact with legacy 802.1D on a per port basis.
In a multi-vendor environment if all devices support it 802.1s MST can be used.
It requires more management efforts because configuration of
MST region name
MST revision number
mapping of Vlans to MST instances
need to match and need to be configured manually.
MST requires a change of mind that is you are encouraged to plan : that is you can divide the 4094 possible vlans in 64 subsets and you can associate them each subset to a different MST instance.
in this way you just need to choice a vlan from a subset and to create it on devices and you get a zero touch MST campus (that is you don't need to modify all those parameters that cause temporary problems as reported by other users).
the advantage is that the vlans don't need to already exist they can mapped before.
For a multivendor environment MST should be the best choice because it allows to build multiple topologies (one for each MST instance) and it is more scalable then Cisco PVST+ or Rapid PVST (it uses an instance for each vlan to be considered low end cisco switches have limits that can be reached in a campus)
Hope to help
Giuseppe
10-16-2009 02:25 AM
hi Giuseppe
thanks for you great help.
one more question, for cisco equipment enviroment, if I want implement VoIP and multi-media sulotion, on basic routing/switching site, what improvement I need consider? for example, I should use Rapid PVST or PVST+?
Many Regards
Julie
10-16-2009 04:58 AM
if I want implement VoIP and multi-media sulotion, on basic routing/switching site, what improvement I need consider?
QoS
You want to make sure you prioritize VoIP traffic and guarantee bandwidth for mission-critical applications such as Video.
Regards
Edison.
10-16-2009 08:44 AM
Hello Julie,
Rapid STP is recommended for VoIP applications
and QoS is very important as Edison has noted.
Hope to help
Giuseppe
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