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Community Member

Low Internet Bandwidth Through Cisco 6509 Core Switch

We have a new internet access with another ISP.  The bandwidth is 100Mbps burstable to 500Mbps.  We have an ASA 5550 firewall (connected to an outside switch), Cisco 6509 core switch and 3750 for access switches (inside network).  

When connected to the outside switch, internet access speed is close to 500Mbps (download/upload).  But when connected to the 6509, internet access speed is less than 100Mbps.  There is a route-map policy applied on the vlan interface for internet access to go through the new ISP.

There are no errors on the interfaces and CPU and memory utilization are low.  No duplex mismatch and interface speed are at 1Gbps (auto or hard set). There are no policy-map for QoS on the 6509.  Only on the 3750 switches for the Cisco IP phones.

Any idea what could be causing the lower bandwidth when going through the 6509 versus connecting directly via outside switch?  Any comment is appreciated.  Thanks!



VIP Super Bronze

What is the make and model of

What is the make and model of the outside switch?  Some providers give you a 4900 series switch for connection to their network to give you line rate or close to it. Is your first Internet access goes through the same 6500? if yes, what is the bandwidth you get? Also, the route-map could be a cause of lower speed. Is there way to test the speed without the route-map?



Community Member

Hi Reza.  Our outside switch

Hi Reza.  Our outside switch is a 3850.  The internet access is a fiber hand-off connected to the outside switch.  The first internet access goes through the 6509 via route-map.  The bandwidth is around 50Mbps.  When bypassing the 6509 using a 3750 (no route-map) I get close to 500Mbps.  Could route-map be the issue?  Here's the route-map:

access-list 101 permit tcp host any eq www
access-list 101 permit udp host any eq domain

route-map NEW-ISP-ROUTE-MAP permit 10
match ip address 101
set ip next-hop

interface vlan 700
ip policy route-map NEW-ISP-ROUTE-MAP





VIP Super Bronze

Hi Rich,The route-map looks

Hi Rich,

The route-map looks fine, but I am sure it will have some overhead and even possibly lower bandwidth.

Depending on the Sup, the 6509 should be able to handle 500Mbps or more.

Can you test the link without the route-map?



Community Member

Hi Reza.  I finally had the

Hi Reza.  I finally had the chance to test the new internet access without the route-map through the 6509 and was able to achieve speed up to 500Mbps (download/upload).  Looks like the route-map has a lot of overhead, somehow.

Community Member

What is the default gateway ?

What is the default gateway ? Where is the in the network map ?

VIP Super Bronze

Hi Rich,Thanks for the

Hi Rich,

Thanks for the feedback. Now we at least know what causes the slowness.  Can you draw a diagram of your network and show how all the components including where the providers come in and connect to your devices?


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