QoS on LAN with 4507 and 3750

[Reddytk98]

Hi Guys,

I've LAN with cat4507 as core and cat 3750 as access switch. There are some Vlan that we used in that network, there are Voice, Video. and some Data Vlan. We use non Cisco Video Camera and non Cisco Ip phone. In our design we set that every video or voice port with only one VLAN only, so we dont mix voice and data vlan (we dont plug PC after ip phone).

my Qusetion do we still need QoS and that LAN. And if needed what is the best QoS method to apply ??. Is there any way to do QoS on LAN based on VLAN ??

here i give my topolgy..

Please help me.. ..

[Reddytk98]

some body help me please....

[Edison Ortiz]

QoS will provide service levels for delay sensitive applications such as voice and video. If you feel your network doesn't have any bottleneck, then QoS may not be needed but again, you aren't providing any SLAs.

Ideally, you want to mark your voice and video traffic at ingress either with DSCP or ACL match, then setting the appropiate DSCP values.

At the inter-switch links, make sure to enable Priority Queueing, so voice traffic can be dequeued before any other packet.

Please refer to the QoS SRND for more info:

http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND/QoS-SRND-Book.html

Regards,

Edison

[Reddytk98]

hi edison

thanks for suggest..

but can you expalin to me why do  i need to configure SLAs on my network..??

thanks

[Jon Marshall · Accepted solution]

You don't configure SLAs as such on your network. SLAs (Service Level Agreements) are defined by the business ie. how long should it take for a certain type of application/traffic to traverse the network etc.

Once these SLAs have been agreed then it is up to the network engineers to configure the network to meet these SLAs. It may be that you don't have formal SLAs agreed with the business but there are still general "rules" ie. with voice traffic Cisco recommend maximum latency figures for example before the voice call becomes degraded.

So if your network is currently working well with both voice/video and data and there is no QOS should you configure QOS. Yes you probably should simply because currently there is nothing to stop one type of traffic affecting another. Data traffic is generally quite resilient ie. it can adjust and deal with dropped/missed packets fairly well. Voice traffic on the other hand isn't. If a couple of your users suddenly decided to download to their PCs very large data files this could have a direct effect on the voice and video traffic.

So that's why the recommendation is when you have a network running voice/data + video you should deploy QOS to guarantee the quality of your video and voice.

As for per vlan QOS, it is supported on some switches and not on others. The configuration guides for each switch can be accessed via the Product pages from Cisco's homepage. They have dedicated chapters on QOS config which will give you all the available options for that switch model.

As Edison has said, you would want to mark voice and video and give them specific queues on the switches with voice being assigned to the priority queue.

Jon

[Reddytk98]

dear All

i think i plan to use auto-qos on my network..

is it correct that i just need to configure "auto qos voip trust" on every video, voice and uplink port..?

in my opnion auto qos should work even i use non cisco ip phone and non cisco ip camera, is that right..???

if Auto qos work, then what dscp value should i input in Ip-phone and camera devices ?? i plan to use dscp : 46(EF) for voice and 34 for video(AF41) .. is it correct or are there any better idea..??

thanks

[Reddytk98]

any sugesstion for me ?

[Reddytk98]

dear Edison or Jon or anybody else..

please give me advice...

[Edison Ortiz · Accepted solution]

For a novice, auto-qos is a perfect fit. Your markings for Voice and video are also correct and auto-qos will make sure those markings are preserved and handled correctly in your network.

Regards,

Edison

[Reddytk98]

dear edison thanks alot for you answer..

one more question : do i also need to set "auto qos voip trust" on uplink port(trunk port), port which is connecting distribution switch to Core switch and port which connecting Core switch and Core switch ???

[Edison Ortiz]

just use the command 'mls qos trust cos' for trunk ports or 'mls qos trust dscp' for access or l3 ports.

[Reddytk98]

thanx alot edison..