From: Sam Munzani (sam@xxxxxxxxxx)
Date: Wed Aug 30 2000 - 16:46:18 GMT-3
IRB/CRB is not an option. In order to cross VLANs you need a layer-3
device. There is no shortcut to it. Cat2948-L3 and other new layer-3
switches uses IRB/CRB as an option to bind some ports together in one VLAN
and route to other such ports in different VLAN.
In those new switches, each port is a layer-3 port and without IRB or CRB
you can't put 2 ports on same VLAN.
With Layer-2 switches, you definately need a layer-3 device either with
Trunking, or from each VLAN have one port connected to Layer-3
device. Second option is fine too but for many VLANS it may not be a
feasible solution. Trunking is the way to go.
Sam
On Wed, 30 Aug 2000 Ron.Fuller@3x.com wrote:
>
> You can always use 802.1q for your VLAN trunking. Very similar to ISL,
> with the exception that 802.1q has one instance of spanning tree for all
> VLANs. This can be a real pain in the butt in some environments. I have
> never tried IRB/CRB for this. I doubt it would work, but someone on the
> list will probably prove me wrong! <g> I have not tried/worked with 802.10
> (SDE)
>
> HTH!
>
> Ron Fuller, CCIE #5851, CCDP, CCNP-ATM, CCNP-Security, MCNE
> 3X Corporation
> rfuller@3x.com
>
>
>
> "Aaron DuShey"
> <aaron.dushey@dushey-consu To: "CCIE \(E-mail\
)" <ccielab@groupstudy.com>
> lting.com> cc:
> Sent by: Subject: vlans
>
>
> 08/30/00 11:42 AM
> Please respond to "Aaron
> DuShey"
>
>
>
>
>
>
> question-
> What other methods are there for routing between VLANs besides
> subinterfaces
> w/ISL?
> Can you use IRB/CRB to do this?
> This is on a 3640 FastE interface.
> Does this mean that if you don't have a 100MB interface on a router you can
> use IRB to route between the vlans instead?
> Little confused here...any help is greatly appreciated,
> The doc cd states-but I am still not completely clear
> Our VLAN Routing implementation is designed to operate across all router
> platforms. However, the Inter-Switch Link (ISL) VLAN trunking protocol
> currently is defined on 100 BaseTX/FX Fast Ethernet interfaces only and
> therefore is appropriate to the Cisco 7000 and higher-end platforms only.
> The IEEE 802.10 protocol can run over any LAN or HDLC serial interface.
> VLAN
> traffic is fast switched. The actual format of these VLAN encapsulations
> are
> detailed in the IEEE Standard 802.10-1992 Secure Data Exchange and in the
> Inter-Switch Link (ISL) Protocol Specification.
> Our VLAN Routing implementation treats the ISL and 802.10 protocols as
> encapsulation types. On a physical router interface that receives and
> transmits VLAN packets, you can select an arbitrary subinterface and map it
> to the particular VLAN "color" embedded within the VLAN header. This
> mapping
> allows you to selectively control how LAN traffic is routed or switched
> outside of its own VLAN domain. In the VLAN routing paradigm, a switched
> VLAN corresponds to a single routed subnet, and the network address is
> assigned to the subinterface.
>
>
> Aaron DuShey
>
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