GigaEthernet to ISP

Unanswered Question
Feb 17th, 2009

We will have a fiber link ( Gigabit Ethernet ) between the office and ISP

ISP will limit the traffic to 30M

What is the best device to terminate the fiber link coming from the ISP, Router ( 3845 or 7200 ) OR Switch ( 3560G ) ?

What is the best practice for this setup ?



I have this problem too.
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Giuseppe Larosa Tue, 02/17/2009 - 08:56

Hello Mohamed,

if you need to do also NAT you need a router and a c3845 is a good choice with space for some rate growth.

if you don't do NAT you can think to use a C3560G.

Be aware that a router gives you more features and the capability to scale better in the signalling plane (number of BGP routes if used)

a multilayer switch provides you much more forwarding plane capacity

Hope to help


Paolo Bevilacqua Tue, 02/17/2009 - 08:57

What do you currently have? Generally speaking, a true router is always preferable for facing the Internet, as it can do FW/NAT/VPN and many other things as well.

Joseph W. Doherty Tue, 02/17/2009 - 13:15

The "best" device is one that both can deliver the performance you require and the features you require. Excluding growth, you've noted one attribute of performance, the 30M, but little in the requirements of features beyond gig Ethernet.

As the other posters have already noted, routers often are more feature rich, L3 switches often provide more perforamance. For 30M, besides the 3845 and 7200, the 3825, 2851 and 2821 routers might be suitable.

Another series of devices you might want to examine, are Cisco's Metro Ethernet switches, e.g. 3750 Metro Series. Such switches often provide the performance of ordinary "LAN" switches with additional features.

Mohamed Sobair Tue, 02/17/2009 - 14:13


The 3845 should be sufficent for handling 30Mbps.

The 7200 with Sup720 is produced to handle upto 400Mpbs IPv4 traffic and 200Mbps IPv6 traffic.



Paolo Bevilacqua Tue, 02/17/2009 - 14:33

Ok, but not on the 7200 and certainly not 400 Mbps. These are figures for ISR routers nowadays


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