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New Member

6509 slow traffic on certain vlans

We have a 6509 with dual sup 1a and MSFC/PFC 6.3(6)installed. I have a server that was placed on one VLAN and only 3 other VLANs including my workstation is on can ftp to this server quickly. Workstations on other VLANs have slow performance to connect and transfer data. I have even tried moving this server to another VLAN but not the ones with slow connections and i am still experiencing problems. My workstation can still quickly connect to this server even on a different vlan but not the other workstations that were experiencing slow connections. We are running HSRP on the MSFC and i have gone through the troubleshooting inter vlan mls instructions. I have also verified DNS for reverse lookups also telnet and ftp seems to like to check.

Could there be issues with CEF, CDP, VTP, or something. I verifed that ports are in full 100 status. It is strange how 3 vlans can communicate quickly while the other vlans connect slow. I have also verifed any ACL or route policy also on the MSFC.

7 REPLIES
Cisco Employee

Re: 6509 slow traffic on certain vlans

Are the workstations that are slow, do they have errors on their ports? If you move a slow workstation to a fast VLAN, is it then fast? Is there something common between the slow workstations: OS, NIC, NIC driver version, errors on port?

Generally, CEF and other switch related problems will cause packet loss, the switch really cannot cause packet to be slow. I suggest you take a sniffer trace of the SLOW workstation and compare it to a sniffer trace of FAST workstation to see the difference.

I would also check over this URL as well:

www.cisco.com/warp/customer/473/46.html

New Member

Re: 6509 slow traffic on certain vlans

The workstations are different brands and i even used a laptop to connect to diifferent vlans and the results are the same. Slow on certain VLAN and fast on the other vlans. So i'm using the same laptop for the test and same hardware. Ports are set to full 100 and show port status has no errors. I didn't setup the 6509 and should i be looking for certain settings maybe for PFC or MSFC features like Qos or priority or something.

Cisco Employee

Re: 6509 slow traffic on certain vlans

There could definitely be something like QOS configured on the PFC or MSFC that could be causing this issue. There could also be a feature configured on the MSFC that prevents hardware based switching. Take a look at the VLAN interface on the MSFC, do you see any configuration in regards to NAT, PBR, or anything else along those lines.

Nevertheless, comparing with sniffer traces will go a long way!

New Member

Re: 6509 slow traffic on certain vlans

I'm not too familiar with Qos commands should i be looking for certain set or on the MSFC config commands. The int VLAN are pretty bare bones no NAT, ACL, or Policy Base Routing. There are VLANS that have PBR but there not going to the slow VLAN. I am using static routing should i enable RIP or EIGRP? As i mentioned though the fast VLAN looks just like the slow VLAN. Could there be hidden areas where you can input commands like you know how you have to do a session 15 or 16 to access the MSFC. Also I did a show mls status/sh mls entry on the MSFC and switch level, and its producing outputs per good running MLS. I'll get a sniffer going but i would figure the catalyst should bridge the two vlans on the same switch quickly.

New Member

Re: 6509 slow traffic on certain vlans

Also I have 3640 routers connected to the 6509 should I enable MLS on the 3640 routers maybe but no servers on the slow VLAN use them. The servers, workstations, and test laptop all go straight to the catalyst 6509.

Cisco Employee

Re: 6509 slow traffic on certain vlans

Enabling MLS on the 3640 will not do anything as the 6500 requires the use of PFC and MSFC for MLS. It cannot use another router for MLS.

New Member

Re: 6509 slow traffic on certain vlans

Are you sure you haven't "fat-fingered" the subnet mask on the vlan interface on the msfc? I have seen this problem when an inconsistent subnet mask has been used.

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