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New Member

Migrating ATM to Gigabit

I need to migrate an ATM network to a 65XX based gigabit network. During the transition I want to use a Catalyst 5500 switch with ATM (connected to Fore ATM switch) and GigabitEthernet (connected to Cat6509 switch) adapter inorder to map the elan vs vlans info.

First, I want to know if it is feasible with the Cat5500.

The Fore swith has Lane services, and there are 4 ELANs defined. Then the Cat5500 switch must have 4 elans defined in their ATM adapter, and 4 VLANs for the ethernet cloud, each one mapped between them. It is correct ? Which are the commands ? There is any config guide document anywhere the web ?


New Member

Re: Migrating ATM to Gigabit

First of all, you should understand the ATM LANE structure. There are 3 basic terms, LECS (LAN Emulation Configuration Server), LES (LAN Emulation Server) and LEC (LAN Emulation client). I can't descript their function so detail here. Please refer the relate document. Traffic bridge between Ethernet and ATM is happen at LEC. LEC will find its LES. Which LES will be used is depends on the LECS configuration. LEC can communicate with other LEC when they join the same LES.

I don't understand your term -- Fore switch has Lane services. If the Fore is working as LECS and LES (for LEC join into), that means your Cat5500 work as a LEC and join to the Fore switch. In this case, you don't have to configure the elans in Cat5500. Just let Fore switch tell Cat5500 the elan information. Using the following configuration and I believe that you can connect your LANE module to Fore switch.

interface ATM0

atm preferred phy A

atm pvc 1 0 5 qsaal

atm pvc 2 0 16 ilmi

lane config auto-config-atm-address

Then, you should have 4 VLANs configured in your Cat5K supervisor engine. After that, you should map your vlan to the elan which learn from Fore switch. Using the follow commands in your LANE module.

interface ATM0.1 multipoint

lane client ethernet 1 elan1

"1" means the vlan number. "elan1" is the elan name. Remember, VLAN use number and ELAN use name as the ID. Please check the Fore switch about the ELAN name.

You can create multi sub-interface at the ATM0 interface of the LANE module. It means you should create more sub-interfaces to perform traffic bridge of each VLAN/ELAN.

I am not sure your 6500 will join to the ATM network or not. If so, you can do the same thing at the LANE module of 6500. If not, you can forget it and just use the trunking (ISL or dot1q) between the 65 and 55.

New Member

Re: Migrating ATM to Gigabit

Thank you Michael, now I understand how to map elan-vlan ids. In order to clarify my scenario:

- The Fore ATM switch has LES, BUS and LECS services

- The Cat5k act as a LEC, joining to the Fore switch LECS/LES.

- I need to use the Cat5k as a "bridge" between the ATM network and the Gigabit network. The Cat5k has a ATM card conencted to the Fore switch (OC-3), and a Gigabit card connected to the Cat6500.

It is a migration scenario between ATM and Gigabit. But the first step to this migration is around the clients (PCs connected to eth/atm switch changing to eth/gbeth swith). In the second step the servers should move from an ATM port of the Fore to an GbEth port of the Cat6500, one at a time, no simultaneously. For the first step, the PCs clients (now under the Cat6500) need to connect through the "bridge" to the ATM servers, before it migrate to Gbeth. This is the reason of the Cat5k bridge function.

As yor recommendation, I need to enable the trunking between the Cat5k and the Cat6500, using ISL maybe. It is our first approach to solve this scenario.

I am in a lab testing this scenario. I will update with results.


New Member

Re: Migrating ATM to Gigabit

Only as an update, the scenario work well, as mentioned in previous message. Thank you very much for your colaboration.

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