Router throughput

[donnymatchen]

Hi all

I have a cisco router plugged into an Xfinity router.  All of the ports on the Cisco router are gigabit.  The BW on both connected ports shows as 1,000,000 kb/s (gigabit).  However, when I do a speed test from a direct wired connection to the Xfinity rotuer, I get 800 mb/s, but connected through the Cisco router, I get around 250 mb/s.  What can I do to fix this bandwidth issue?  Could double-nat cause that much latency?

interface GigabitEthernet8
 ip address dhcp
 ip access-group wan in
 ip access-group nosrv out
 no ip unreachables
 ip nat outside
 ip virtual-reassembly in
 duplex auto
 speed auto
 ipv6 address dhcp
 ipv6 enable
 ipv6 traffic-filter wan_v6 in
 ipv6 traffic-filter nosrv_v6 out
!

[Joseph W. Doherty]

What specific Cisco router?

BTW, smaller Cisco routers might not be able to support all their ports, or any, at (continuous) wire-speed.

[donnymatchen]

the name on amazon was:

Cisco C892FSP-K9 1 GE and 1GE/SFP High Perf Security Router RENEWED

sold by amazon renewed.  Does the C892 not actually perform gigabit routing?  Is there a good way to test if the hardware is defective?

[Joseph W. Doherty · Accepted solution]

"Does the C892 not actually perform gigabit routing?"

No, although it has been "clocked" as capable of forwarding 1.4 Gbp (remember for gig, you would need up to 2 Gbps, for

duplex

but that rating is generally not possible in "typical" real-word routing.

Cisco actually recommends the 890 series for up to 15 Mbps, but that's so low to pretty much guarantee it can be achieved regardless of traffic kind or configuration options being used.

For "routine" traffic and configurations, you're likely to be able to achieve 50 to 100 Mbps (aggregate) bandwidth (for IPv4, IPv6 might be slower too).

I've attached a Cisco paper that discusses obtainable throughput, for various Cisco routers (including 890s) for different traffic kinds and configuration.

[donnymatchen]

Thanks, an important lesson I won't forget.  Kind of unethical for amazon to be selling this item as a gigabit router, but at least their return policy is generous.