Flex Port on Cisco ISR 1100 performance implications

[fabios]

Hello everybody,

I am in the process of deploying a C1161X-8P. The router has 2WAN ports, 8 LAN (layer2) ports of which 2 can be reconfigured as Layer 3 (wan?) reference:

Cisco 1000 Series Software Configuration Guide, Cisco IOS XE 17 - Configuring Ethernet Switch Ports [Cisco 1000 Series Integrated Services Routers] - Cisco

This is all nice and good but I cannot find any information about the performace of these flex ports.

I guess that switching at layer 2 would use the "catalyst" switching fabric but what happens after issuing the "no switchport" command? Is there any performance impact compared to a wan port routing performance? I need to use multiple WAN ports because the Internet connectivity is delivered with multiple PON (passive optical) using (ONT - Optical Network Termination) which is CPE not under my control and on these the PPPoE traffic is on 802.1q VLAN 835 on both while the ONT management traffic is untagged (and on 192.168.0.x/24!) so there is no way I can connect both to a layer 2 switch without creating a conflict. Obviously I need to create a subinterface dot1q 835 on both!

I cannot find any documentation and a brief search of the community yielded no results.

Thanks for any help or pointers to relevant docs.

Cheers

Fabio

[Joseph W. Doherty]

Is port performance your only concern?  What about overall L3 throughput?

I've attached a couple of PDFs that address this series performance.

[fabios]

Thanks @Joseph W. Doherty 

Very interesting documents could not dig them out myself.

My concern was if there was any difference in performance  in the Flex ports configured as layer 3 vs the pure layer 3 ports.

The overall L3 performance is of interest of course, considering that there will be 2 Gigabit fiber connections to the internet but:

1. I do not expect to exceed the (unencrypted) router performance combining the 2 interfaces (1.8 Gbps no NAT 1130 Mbps with NAT)

2. the two connections will be backing each other up (using SLA and event manager)

3. there will be NAT involved but not SD-WAN which is the reason why I selected the 1161 (higher clock with higher IP NAT routing  performance) and X (8GB) for future proofing; also IPS to secure the network (also CPU intensive and probably need those 8 GB DRAM!)

I will need a Security license (IPSEC and IPS). Wonder if it can be activated as eval for 30/90 days while ordering the PAK.

Thanks

Fabio

[Joseph W. Doherty · Accepted solution]

"My concern was if there was any difference in performance in the Flex ports configured as layer 3 vs the pure layer 3 ports."

Prior reply and this reply, working from my phone, so difficult to review the two documents I provided.

Don't know for sure (might be clues in architecture document), but as you don't anticipate running all 4 ports flat out, I suspect you might be okay.  (Also, later small ISR designs seem to provide more bandwidth between the core and "module" like ports that may become bandwidth demanding between themselves and core.)