Replacing remote office T-1s' with Metro Ethernet (ME)

Unanswered Question
Apr 30th, 2009

Hi All,

We are looking at replacing/upgrading some of our remote branch offices WAN access connections (currently T-1's) and going to Metro Ethernet (10MB provision from AT&T). Since I have not had much experience at all with Metro Ethernet I was wondering how the setup might be.

Questions:

Do you use a router at the remote end or can you use a L3 siwtch like a 3560 for example? Not sure of the configuration either, but I am sure it can't be that difficult. I am picturing the setup as a long ethernet cable...;-)

Also what would need to be at the headquarters end for termonation? Would something like an additional L3 3560 work.

Thanks,

Brandon

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Jerry Ye Thu, 04/30/2009 - 06:56

Hi Brandon,

If you are going to use a switch, I see a lots of people are using it for the Metro-E solution, you should consider the 3750 Metro Series. 3650/LAN switches cannot do shaping on the switchport. Since shaping should be implemented when the guarentee speed (CIR) is lower than the port speed to avoid packet drop for drop sensitive application. LAN switches doesn't have the QoS mechanism of a ME switch/router.

HTH,

jerry

mbroberson1 Thu, 04/30/2009 - 07:05

Hi Jerry,

At the remotes could I use something like a 2811 router (since it has better QoS capabilities), and for the remotes LAN access hang a L2 switch off the router?

If you used a router at the remote ends, could these just terminate to a 6500 L3 eithernet port at the headquarters end?

Thanks,

Brandon

Jerry Ye Thu, 04/30/2009 - 08:18

Hi Brandon,

If you prefer, you can use the 2811 at the remote end. You might be able to get more features off the 2811 than the 3750-Metro.

At the HQ, if you are going to use a 6500, make sure you are using the SIP/SPA line card as the L3 ethernet port. Since the WS-X6x48, are LAN line card where it cannot perfrom shaping.

HTH,

jerry

mbroberson1 Thu, 04/30/2009 - 08:50

Hi Jerry,

Can you briefly explain the typical setup (specifically for QoS) for metro ethernet. Our site has about 10 remote sites with PtoP T-1's. Configuring QoS on these is done on each individual end-point's egress interface. In the case of ME if you have 10 remote sites that's 10 remote interfaces, but at the headquarters end you have only one connection...how would you configure the QoS? Is it kinda like FR? I really am new to the ME type of setup. Am I correct that with ME you would not have an individual "circuit" for each individual branch.

Thanks,

Brandon

Jerry Ye Thu, 04/30/2009 - 09:58

Hi Brandon,

I am using a hub and spoke topology and your sites as an example.

You have 10 remote sites (spoke sites), and they are only talking to the HQ (hub site). At the hub site, you have a single ME connection to the network (cloud), which is similar to the FR point-to-multipoint connection (since ME cannot do PVC, if you would like to do some type of PVC, you can use tunnel or Vlans). When you want to do QoS on this type of connection at the hub site, you will use HQoS to shape the aggregated traffic to the CIR, and then you can shape each connection to the spoke accordingly.

At you remote site, you have to be careful with the QoS parameter, since the aggregation point is the hub where it has only 10MB (I am assuming all sites are getting 10MB link), and not to saturated you 10MB at your hub site.

HTH,

jerry

mbroberson1 Thu, 04/30/2009 - 10:09

Hi Jerry,

Yeah, I think we are getting 10MB at the remotes and something line a 50MB connection at the hub/aggregation site.

Thanks,

Brandon

Jerry Ye Thu, 04/30/2009 - 10:23

Hi Brandon,

Okay, this sounds much better. I am not sure what is your design and I am assuming you are going to have hub and spoke setup for ME also.

So, in this case, you can shape your remote site to 5MB and shape each of the connection (via ACL or tunnel or VLAN) to your remote site at your hub site to 5MB. Assumeing ISP is give you 50MB CIR at hub and 10MB CIR at spoke.

HTH,

jerry

Joseph W. Doherty Thu, 04/30/2009 - 10:27

The two issues that you often encouter with Metro Ethernet are: your WAN routers might be incapable of providing sufficient Ethernet bandwidth forwarding and you might now have a multipoint vs. individual links topology.

Instead of a "long ethernet cable", think more of L2 Ethernet switch that now connects your site network devices, which often offers less bandwidth, more latency, and often provides you no direct control over it.

You can continue to use a "router" at each site, or you might migrate to a L3 switch. (As mentioned by another poster, a "Metro Switch" is another device option.) Choice of device depends on nessary features vs. performance. Router tend to be most feature rich, least performance; L3 switches most perforance, least features; and metro switches more features but still with L3 switch performance.

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