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Seeing no traffic in MSFC in core switch.


We have two core switches at clients site.Both the core switches are connected to WAN individually.So there are two WAN circuits. There is also a link between the 2 core switches.

One of the core switch-1 catalyst 6509 is showing no traffic in MSFC on vlan interfaces although it has spanning tree forwardoing ports from the access switches and it is also HSRP active switch.

What i am seeing that traffic though comes on link to this switch from the access switch but then it goes to the other Core switch -2 using the link between and it exits to WAN.

There hardly any traffic that exits from Core switch-1. I have checked routes , both the core switches have same routes from MPLS provider.

Any suggestions?

Thanks in advance.

Hall of Fame Super Silver

Re: Seeing no traffic in MSFC in core switch.

Hello Saju,

are the two boxes running the same IOS version?

on some older versions the effect of multi layer switching was to show very few traffic on SVI vlans far lower then real.

for return traffic box2 can be preferred for some reason.

But if HSRP active is on box1 it should be used by hosts on the client vlan.

Hope to help



Re: Seeing no traffic in MSFC in core switch.

Hi Guiseppe,

Thank you for your response.

yes the other core switch is 5000 series platform.

Do you know any bug id for it? To which IOS should i upgrade to? any suggestions.



New Member

Re: Seeing no traffic in MSFC in core switch.

Are you running BGP to the MPLs cloud? If so its common to see BGP to install a single path in the AS database and not load share. Even if you are not running BGP the carrier is and BGP will not load share by default. Post more info on the routing and we can assist further,