WAN upgrade to Metro/Ether

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Nov 11th, 2007
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I have 4 remote sites on FR connections coming back to the head office on ATM. Each site has one voice, three data and one management VLAN. All VLANs are trunked with dot1Q.

My frame-relay/ATM provider is upgrading us to a product which amounts to a metro ethernet type solution, with remote branches running at 10Mb/s and the central office being 45Mb/s. There isn't enough room here to ask the questions I have in my head, but here are a few things I am in a quandry about.

1. Should I simply move the meat of my current branch router configs to L2/L3 capable switches, transfer all of the VLAN data to them and make one interface the routed one.

2. VTP? Is there any downside to running it in server mode at the core central office and client in all of the branches.

3. I have SRST for my voice system setup through analog lines in each branch connected to fxo/fso modules in each router. Is there anyway to do SRST without a router sitting in each branch?

If you can think of other issues I may run into, please let me know.

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Overall Rating: 4 (1 ratings)
lgijssel Mon, 11/12/2007 - 01:23
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One thing that you'd better not do is spanning your vlans across a WAN link, not even when it's ethernet. This will make your broadcast domains too large and result in bad response and all kinds of other problems. Hence, also no vtp across the WAN. keep your vtp domains local, one per site.

The best way to utilize such a link is as a routed connection. You can use routers or L3 switches for this.



Mark Hovey Mon, 11/12/2007 - 07:44
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My plan was to definitely route on the Cat 3560 switches in each branch. But I haven't done this before so I am pouring over Cisco docs to see what to do after I execute the "no switchport" command. Is L3 configuration as versatile as with a router when you have the EMI image installed?

lgijssel Mon, 11/12/2007 - 09:16
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"Is L3 configuration as versatile as with a router when you have the EMI image installed?" I would say it is, at least it knows eigrp and ospf which are both suitable as routing protocols for this environment.

Instead of putting in "no switchport" you may also implement the entire Metro-WAN as one vlan. Using ports in access mode gives you untagged traffic and is virtually identical to the above. I personally find this solution gives more structure to the config than working with "no switchport".



Mark Hovey Mon, 11/12/2007 - 10:04
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When you say "implement the entire Metro-WAN as one vlan" how would I then handle the segregation of my trusted data and voice traffic from my untrusted data and wireless traffic. I achieve the isolation now by having multiple vlans in each branch, encapsulated and sent through ethernet subinterfaces on a router.

Something else just struck me...the routers all have a Loopback0 configured like this:

interface Loopback0

ip address

h323-gateway voip interface

h323-gateway voip bind srcaddr

Is this config required or possible or needed on an L3 switch?


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