QOS across multiple VTP switches

[gilesc]

I am trying to rationalise the company network. At the momement we have three layer 3 switches connecting our sites together which have QOS inplemented for a VOIP link. However I would like to move to a fully VTP network where I can save on cabling.

Most of the vlans (7) are easy it is just that I don't know if I need to enable QOS on all the switches in the network or just the ones that will be handling the VOIP traffic.

The infrastructure is 2 x cisco 4500 switches acting as the core switches and routers with a mixture of 3548 and 3550 48 port switches at the wiring cabinet. At the least I will need to reflash a couple of these to make them layer 3 devices but I hopefully don't want to flash the rest as there are another 30 out in the building.

Thanks in advance

Giles Cooper

[davekbell]

Hi,

I'd recommend enabling QoS on all ofthe switches/routers that are on the same paths that VoIP calls can take. Define specific policy/class maps in the call directions to ensure good voice quality.

Regards,

Dave

[andrew.butterworth]

Giles

Can you explain what you mean by the following as it isn't clear:

'However I would like to move to a fully VTP network where I can save on cabling.'

With regards to QoS only the 4500 (as long as you have Sup II+ or above) and the 3550 support QoS (the 3548XL has QoS but it isn't configurable).

HTH

Andy

[gilesc]

Andy

Let me try and explain myself better - due to the current network infrastructure we have a lot of direct cable links between wiring cabinets (where there should have been VLAN's originally) and we are running out of them.

There is not on the current system a VTP domain configured so we can't easily change this over.

I am now putting in new 4510R switches with supervisor v engines to replace the old 4006 supervisor ii controllers. I will be implementing a full vtp domain across the ~30 other lan switches at the same time as the install.

However the problem is that with the 2 voip lines can I still pass the data over the 4500s without needing to write QOS configuration on all the other switches or do I just need to do this on the switches that actually need to handle the data.

My other option is to just leave the voip connections as they are currently and not worry about having just two patch cables directly connected. (the telecoms switch is at the other end of the building to the switch the line needs to be plugged into.

The second option does seem to be the easier one at the moment though...

Giles

[andrew.butterworth]

Giles

Whether it is a VLAN trunk or an access port you still need a cable? Or do you mean you have multiple cables between each access switch and the core/distribution each configured as an Access Port in the different VLANs?

If you know the exact paths the VoIP traffic will take (and any redundant paths in the event of a link failure) then you can engineer these links for QoS quite easily.

A diagram might help?

Andy

[gilesc]

> Whether it is a VLAN trunk or an access port you

> still need a cable? Or do you mean you have multiple

> cables between each access switch and the

> core/distribution each configured as an Access Port

> in the different VLANs?

I have the latter situation where multiple cat 5 cables are used to connect the different vlans instead of the backbone.

I've attached a diagram below, the top section shows the current system and the bottom part is my proposed design. I basically want to take the direct cat 5 connection out of the system and use the fibre links instead - however this time the system will have a choice of core switch to go through in the event of a system failure.

Giles

[andrew.butterworth]

Looking at your diagram I am still confused. The 3 VoIP Switches, are these 3550's and the LES100's configured as VLAN Trunks, and you have a single Voice VLAN between all 3 sites?

If this is the case and you intend to mold it all together I would stop as you are likely to impact on voice quality unless it is properly thought out.

It may be worth putting together a clearer diagram including IP addresses etc.

Andy

[gilesc]

Andy

Thinking about it over the weekend the voice vlan does not need to be routed and I am now going to leave it on the direct cable connections to the comms room. I was looking again at the work involved to just implement the new switches and as I have just an 8 hour windows (which includes mounting the switches in the rack) it is going to be too tight to do any fancy work on the voip link.

Thanks for your help, as you have persuaded me away from a potentially disasterous situation.

Giles