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100mbps Routing to Internet??


Thanks in advance for any replies.

I have a client that is currently running MPLS to connect a handful of corporate sites (VOIP and data traffic). All internet traffic is routed to the corporate HQ (site A) where there is a T1 connect to the internet.

They have the opportunity to get a 100mbps internet connection at their HQ for dirt cheap. My question is: How do I integrate the 100mbps internet connection into the existing network and be able to take full advantage of the high speed? I have attached a diagram that shows the basic layout of the network.

The HQ (Site A) uses a 1710 router with a pair of WIC-1DSU-T1's to connect to the existing T1's (one T1 connects to the MPLS network, the other to the internet). The fast ethernet port on the 1710 is connected to a PIX 515e, which in turn is connected to the LAN and DMZ. Remote users also connect to the corporate network using the PIX VPN.

The proposed change would provide 100mbps internet over ethernet. The ISP would bring a fiber optic cable into the server room. From there we connect using either a ST fiber connector (directly to the ISP fiber) or to a media convertor provided by the ISP (converts to 100mbps twisted pair - CAT5).

Since the 1710 only has one fast ethernet port (which goes to the PIX), I can't connect this to the fiber media converter. I do have a WIC-4ESW (4-port fast ethernet switch) that could be used in one of the WIC slots (assuming that one of the WIC-1DSU-T1's will not be needed when the internet T1 is shut down). I know that the WIC-4ESW will not work in 1710, but will in a 1721, which can be purchased relatively cheaply.

From what I have read, the 1721 can provide a maximum switched throughput of 6.14mbps. Does this mean that if I use the 1721 to connect/route to the internet, I will only get (at the most) 6mbps of throughput (essentially wasting 94% of the available bandwidth)? Or am I misunderstanding how this works?

Can anyone offer any other realistic solutions? The lowest cost router that can switch at 100mbps is the 2851, which would cost $6000-$7000 used.

Could I connect the internet directly to a fast ethernet port on the PIX and define my default route out through this interface? What would be the downside of letting the PIX do the routing and not using a router at all?

Thanks for any help that can be offered.

5 Replies 5


You can use the 100 mbps connection directly terminated on the pix. Your remote sites can still hang off the 1710, whose ethernet goes into the DMZ of the PIX. I would not put the 1710 on the outside of the PIX, as your remote sites will be wide open to the internet.

check attached picture that is edited.

Cost of doing this,

a. $$ for purchasing fiber to ethernet converter

b. $$ for purchasing additional nics for PIX

c. $$ for purchasing UR licensing so that PIX can support more than 3 nics. (upto 6 on pix 515)

d. Time required to reconfigure rules on PIX firewall, 1710, vpn users etc.

PS: please rate the post if it helped you!

Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus

the PIX upgrade to UR would cost over $3000. It would be cheaper to buy another restricted PIX just for the internet connection.

am i correct in my understand that the 1721 cannot route packets at 100mbps?

Going to a UR version of the PIX has more advantages than going to a seperate PIX not the least of which is one less device to manage.

On the WAN side the 1721 can do up to 2Mbps.

WAN Interface Specifications (Optional)

Synchronous serial interfaces on serial WAN interface cards

Interface speed: up to 2.0 Mbps (T1/E1)

Synchronous serial protocols: Point-to-Point Protocol (PPP), High-Level Data Link Control (HDLC),

Link Access Procedure, Balanced (LAPB), IBM Systems Network Architecture (SNA)

Synchronous serial WAN services: Frame Relay, X.25, SMDS

Synchronous serial interfaces supported on the WIC-1T, WIC-2T, and WIC-2A/S cards: V.35, EIA/TIA-232, EIA/TIA-449, X.21, EIA-530

There is a 10/100Mbps hard-wired interface for the LAN connection. You will not be able to get a full 100Mbps through it but it will handle standard network traffic, especially since WAN routers are typical bottlenecks anyway. 100Mbps network routing to a 1.5Mbps Internet connection for example.

Hope this helps. Please remember to rate all replies

Note that 1721 has only one 10/100 interface. To add another interface you have to use a wic-1enet which is 10 mbps.

With fast switching/CEF enabled, the PPS with 64 bytes packet size, is 12000. (@ 6 Mbps throughput)

cost of 1721 - 1200$ (approx)

cost of 2851 - 6500$ (approx)

cost of a PIX - UR upgrade - $4000 (approx)

Even if you get a router with 100 + Mbps througput, the question is whether you are going to subscribe that much bandwidth.

PS: Please rate the replies if it helped you!

Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus

going back to my original question: if I install a WIC-4ESW (4-port 100mbps) in a 1721, would I get 100mpbs throughput between any of the fast ethernet ports? of just the 6mbps? My client is looking to jump on a 100mbps fiber connect to the internet. How much of that bandwidth can we make available to LAN users? If we bring that 100mbps directly to the PIX (bypassing the router) can the PIX route fast enough to make use of this? Or will the speed still be degraded to < 10mbps?

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