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Re: L3 routed network [7:125087] posted 08/14/2007
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I just want to point out that the only L3 broadcast domain is a single 
access switch itself and localised at that. The access switch would be 
configured with 'no switchport' and hence connected with a point-to-point 
routed link to the distribution. Same thing for distribution->core and all 
over the network

Is your response still the same?

Thank you

""Neal R""  wrote in message 
> Each access switch should attach to two distribution switches. One
> distribution switch is primary for HSRP and the other secondary. This
> scheme follows through on the back(core) side, by adjusting routing
> metrics such that the primary HSRP switch is favored in both spanning
> tree and routing metric calculations. Core/distribution is a little less
> clear cut and depends greatly on what resource consumer/producers exist
> and where they are.
>  The access, distribution, and core layers are drawn with separate
> switches in the Cisco propaganda. They could also be called the layer in
> which gross profit comes from many low margin devices, the layer in
> which gross profit comes from some medium margin devices, and the layer
> in which high gross profit is achieved with pairs or quartets of very
> high margin modular devices. Notice that there isn't a "you get a nice,
> fat raise layer" anywhere in there ...
>    Access, distribution, and core are *functions*, not separate
> concentric rings of switches. It is very common to find access and
> distribution functions collapsed with core functions found in routers
> which also aggregate WAN links. It is even more common to find lots of
> 29xx and 35{12|24|48} which need the distribution/core function
> installed to partition an overlarge broadcast domain. A network needing
> separate access, distribution, and core must be very large indeed, or
> have certain geographic characteristics, such as a multibuilding campus
> in which access and distribution are done per building along with
> access, distribution, and core functions found in the building housing
> the datacenter functions for the campus.
>     Stop teasing and tell us how many widgets are in each physical
> location and what the interconnection is like :-)
> Bill Wharton wrote:
>> L3 routed network and usage of HSRP,GBLP,etc
>> I'm designing a L3 routed network - L3 from core -> distribution ->
> access.
>> Hence, the only L2 would be the local access switches themselves and
> VLAN's
>> would not span a single access switch or 3750 cluster
>> Now, would I need to use HSRP/GBLP/VRRP anywhere in the design? I don't
> see
>> a reason to anywhere. Some access switches may connect to a single
>> distribution while other access switches may be dual-homed to two
>> distribution switches. However, with dual-homing, I'll simply use EIGRP
>> equal cost paths
>> Also, all distribution switches would be dual-homed to the two cores.
>> Anybody differ?
>> Pg10 of this guide states I should be using one of these redundancy
>> protocols hence the confusion

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