Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

To L3 switch or not.... Rtr upgrade or split w/ L3 switch + rtr combo

Currently I am debating a router upgrade at our colo. The routers in question are border internet routers at the moment, connecting us to the ISP (Via Ethernet). The router uses Ethernet connectivity for the primary route path, but supports about 3 Mbps of MPLS MLPPP frame connectivity (2xT1's). It does IPSec endpoint termination for about 3Mbps of 3DES over the Ethernet side, and runs BGP (mainly for the MPLS connection). Peak Internet loads are about 30 Mbps. I am looking for a new device to run up to about 100Mbps, wire speed.

I have considered taking the existing 3745 router solution (everything runs on here) and decoupling the IPSec and MPLS connectivity from the primary Internet connectivity. This might allow me to run a 100Mbps L3 switching solution for the primary routing function, as opposed to buying a much more pricy 7X00 routing solution. So for example, I might run a 3750 L3 switch pair for the BGP/Ethernet routing and a 3725/45 router pair for the IPSec & MPLS frame piece.

What do you think? Any ideas?


Re: To L3 switch or not.... Rtr upgrade or split w/ L3 switch +

In theory it should work. A L3 switch is rated at much higher rates than a router but there are a number of features that are not in the IOS image because they cannot be done at wire speed.

If you can live without those then a layer 3 switch is a good option. Another concideration is that most smaller l3 switches do not have enough memory to take 2 full bgp internet routing table.

If you are going to use existing 37xx routers then that is a good reason. For new routers there is not a lot of difference in the pricing on a 3800 and a 3700 series router. The 3800 series is much faster and includes a hardware accelerated IPSEC. Depends on which speed charts you look at but a 3845 can pass almost as much data as a 7200 with a npe-400.

Since you plan to offload most your traffic to the l3 switch you may be able to use a 2800 series router. It will depend if you need to load the huge internet routing table on this router.

New Member

Re: To L3 switch or not.... Rtr upgrade or split w/ L3 switch +

Hi thanks for reply. One confusing piece is your throughput comparison of 72xx and 38XX. Here is link for 7200 which shows upt to 1.8Gbps:

Here is link of 3845 which shows 54Mbps:

So it looks like the 72XX series can handle much more traffic than 3845???