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Want to give E0 preference to S0 over E1

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Dec 22nd, 2003
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I have an old 2511 running 12.2(13).

We have a remote office connected to HQ via 1.5meg Frame Connection.

We currently have the entire office on E0. The office is divided into two departments, Support and Sales.

When ever the support guys start downloading large attachments or FTPing files to/from sites, etc, the sales guys cant get to the accounting systems and Databases.

I wanted to move the Support guys to the second interface and do some QOS or something to give the sales guy's traffic priority on the serial link.

How can I set this up on the 2511 with IOS 12.2(13) Or can I?



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Georg Pauwen Mon, 12/22/2003 - 14:18
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Hello Scott

I would use class-based weighted fair queueing and prioritze all other traffic over the FTP traffic, You do not need to split the user groups across interfaces for this. IOS 12.2(13) should be sufficient for Class-Based Weighted Fair Queuing (that is what this is called). The configuration would look like this:

Router#conf t

Router(config)#class-map match-all ANYTRAFFIC

Router(config-cmap)#match access-group 101


Router(config)#class-map match-all FTP

Router(config-cmap)#match access-group 102


Router(config)#access-list 101 deny tcp any any eq ftp

Router(config)#access-list 101 deny tcp any any eq ftp-data

Router(config)#access-list 101 permit ip any any

Router(config)#access-list 102 permit tcp any any eq ftp

Router(config)#access-list 102 permit tcp any any eq ftp-data

Router(config)#access-list 102 deny ip any any

Router(config)#policy-map PRIORITY

Router(config-pmap)#class ANYTRAFFIC

Router(config-pmap-c)#set precedence 5


Router(config-pmap)#class FTP

Router(config-pmap-c)#set precedence 4


Router#conf t

Router(config)#interface Ethernet0

Router(config-if)#service-policy output PRIORITY

With this configuration, all other traffic is prioritized over FTP traffic.

Use the command:

show policy-map interface Ethernet0

to check that FTP packets get another (lower) priority than all other traffic.

Let me know if that is not 100% clear...:)



mmolina2 Mon, 12/22/2003 - 15:08
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I could very well be wrong but wouldn't you want to apply the policy-map inbound on E0, or perhaps outbound on the WAN interface to keep the WAN queue from getting overrun by the 10Meg Ethernet traffic ? I wouldn't think there would be a problem in the WAN to LAN direction. Again, not a big QOS guy so I could be wrong.

kkalaycioglu Mon, 12/22/2003 - 23:11
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Won't you need on the other side of the WAN link in outbound direction? Especially for FTP case?

Georg Pauwen Tue, 12/23/2003 - 02:17
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indeed, you are right, applying the policy outbound would affect traffic originating on the LAN.

The policy needs to be applied inbound in order to affect traffic coming from the outside:

interface Ethernet0

service-policy inbound PRIORITY



kkalaycioglu Tue, 12/23/2003 - 06:07
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I'm not an expert on QoS solutions but I'm a bit confused. First let me explain what I understand from your problem description: You've got two user groups (say two subnets) on LAN and these hosts reach to the rest of the world using a WAN link. And salespeople is complaining about the FTP traffic of the technicals. My first point: at the moment of the congestion this will occur on interfaces connected to the WAN link. Don't we need to apply any QoS config to the WAN interfaces? Assuming I don't know diretction of FTP and other flows, applying outbound CBWFQ to both router WAN interfaces makes more sense to me. Another point is that instead of setting IP precedence field in IP header applying a "bandwidth" command under the policy-maps with appropriate value looks more simple and manageable.


e.tantsura Tue, 12/23/2003 - 06:04
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There is not much to do for downstream because of speed mismatch 1.5/10 - your bottleneck is WAN, you could try RED for ftp and slow down whole tcp session.

For upstream you could use CAR & RED on ethernet and just drop out of profile traffic of coloring on ethernet and CBWFQ & policing/shaping .

Don't use tail drop for ftp, tcp doesn't like that :)

stownsend Mon, 01/05/2004 - 09:14
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Thank youl all for your replies.

I guess I should have not used FTP as an Example. (-; Its FTP, HTTP, Windows File Server Transfers, pretty much anything that they can download big files from, they will go it.

Thats why I figured it might be easier to move the Support guys over to the second interface and then just five priority to the Sales guys interface over the Tech people.

The Sales guys are just sending small packets. Mostly just Mail, Remote Desktop Sessions and a few small SQL Queries. So they hop on the line, get the info anf get off. It jsut seems that when someone in the Tech departments tries to load the latest security patches on the 12 Classroom computers, the network dies for the sales guys.




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