Ethernet Switches & Routers

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New Contributor
Posts: 2
Registered: ‎01-02-2011

qos on foundry switches

Hope to understand the marking/qos on foundry switches, if a device send a packet with dscp 40, will this packet won't be changed and will be in the priority 5 by default without any configuration on the switch? Thanks

CMD
Contributor
Posts: 52
Registered: ‎02-18-2010

Re: qos on foundry switches

Hello,

This will depend on the model of switch you are using. Here is some information out of the Configuration guide:

FastIron GS, LS, WS, and CX Series devices support DSCP-based QoS on a per-port basis.
DSCP-based QoS is not automatically honored for switched traffic. The default is 802.1p to CoS
mapping. To honor DSCP-based QoS, enter the following command at the interface level of the CLI.
FastIron(config-if-e1000-11)#trust dscp
Syntax: trust dscp
When trust dscp is enabled, the interface honors the Layer 3 DSCP value. By default, the interface honors the Layer 2 CoS value.

FastIron X Series devices require the use of an ACL to honor DSCP-based QoS for routed traffic in
the Layer 3 image, or for switched traffic in the Layer 2 image. To enable DSCP-based QoS on these
devices, apply an ACL entry such as the following.
FastIron(config)#access-list 101 permit ip any any dscp-cos-mapping

If you are using a different model of switch, please specify.

Please let me know if you have any other questions.

Thanks,

Chris

New Contributor
Posts: 2
Registered: ‎01-02-2011

Re: qos on foundry switches

Hi Chris,

Thanks for the information, based on that, I'd like to expand a little bit.

access-list 110 bridged-routed

access-list 110 permit tcp any any eq 1720 dscp-marking 40 dscp-cos-mapping

access-list 110 permit udp any any eq 1720 dscp-marking 40 dscp-cos-mapping

access-list 110 permit tcp any any dscp-marking 0 dscp-cos-mapping

access-list 110 permit udp any any dscp-marking 0 dscp-cos-mapping

access-list 110 permit ip any any

inter ve100

ip access-group 110 in

exit

So with this, on the edge switch FSX, only tcp and udp ports 1720 are marked with dscp 40 and they will use the default map so they will in priority 5, the rest of traffic will be marked at 0.

On the Layer2 uplink of upstream NetIron MLX, I'll put trust dscp on the interface.

Let me know if above configuration is correct.

BTW, what is your recommendation for Bearer Traffic priority on Froundry switches? 5 or 7 ?

Thanks again.

Occasional Contributor
Posts: 10
Registered: ‎04-03-2012

Re: qos on foundry switches

Is there a way to modify this ACL (110 from above) with out deleting it or affecting traffic?

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