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New Member

Designing of network using L3 Switch


Find attached the layout of the site.

Here Site B has to be built?

Site A and Site C already operational.

I don't have much information than the layout.


1.MPLS link will be over the fiber.How should I terminate the link to my new site(maximum 50 users using mail server sitting in main office).Will that work with L3 switch?If yes suggest me the model with gigports.Where should I terminate the link.How to do routing etc.

2.The link coming from across the country is also to be connected.What are the way I can use this.I don't know how Site A and Site C are connected.What are the diffrent ways it can be connected.(isp across the country is different from my local one).Is it through MPLS or something diffrent?Do I need router at my end as well?How can I use this link with My L3 switch for internal distribution.

3. I want to go with backup line from my Site A to Site B,in case of link failure.How will this failover work automaticaly.

4.Should I go with S licese or E license of L3.Somebody suggested that on new site just L3 switch is required(nothing else).I need expert opinion in designing and making it live.

Thanks in advance.



Super Bronze

Re: Designing of network using L3 Switch

Not enough information to accurately answer your questions, but for some "food for thought", a L3 switch might suffice, alone, at your new site if it supports the necessary physical handoffs (e.g. Ethernet copper/fiber) and supports your routing methodology (e.g. RIP/OSPF/BGP).

Using an "ordinary" LAN L3 switch, in this type of situation is often the most inexpensive option, but not always the best. Such switches are designed to provide maximum performance, often at the loss of many of the features found on most WAN routers. There are a class of L3 switches, that add back some of the more important WAN features, often known as Metro Ethernet switches. An example of a comparison of these two types of L3 switches is Cisco's 3750 Series vs. their 3750 Metro Series.

Aside from using either type of switch, you might want to carefully consider whether a router would be better. The current ISR routers, besides having almost any WAN feature you might need, offer a extensive set of options. For example, in your situation if you used a 3845, it could support Ethernet switch module(s) (provide the Ethernet ports for local hosts) and/or WAAS (Wide Area Application Services - attempt to provide WAN access at LAN performance) module within the router chassis.

With regard to you questions about MPLS, MPLS usually ties together different sites, often such they all can directly access all the others. There are several different ways of doing this with MPLS. It would be unusual to use two providers for different sites, since different MPLS providers often do not communicate with each other. Perhaps what you have in mind is different local ISPs providing the link from each of your sites to the same MPLS provider.

There are several methods to have automatic failover between you primary link and the secondary. It also might be possible to use both at the same time. How either is accomplished is dependent on your equipment capabilities and how its been configured.

New Member

Re: Designing of network using L3 Switch

Thanks for the input.

Well I found that out of two different links one link is point to point and other one is mpls and both will be provided on ethernet interface in my premises.

Here need some configuration help to configure it on my(no router at my side)L3 3750 switch.Any hint or url will be of gr8 help.

Thanks for such useful info.



Super Bronze

Re: Designing of network using L3 Switch

If your connections are Ethernet, then connect them to either copper or SFP ports depending on the connections' physical media type and bandwidth required (i.e. the same for any other Ethernet connections).

Beyond that, it isn't really defined whether the connections will be L2 or L3; if L3, what type of routing protocols, in any, being used. Such considerations will determine how the 3750 should/might be configured and what feature set is required. For instance, the base 3750 image supports static routing and RIP but a more advanced feature set image will be needed for OSPF/EIGRP etc.

"How to" information can be found on the Cisco site within the configuration guides, reference manuals, configuration examples, etc. for the 3750. E.g.

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