Hi there, Say if I had a qos appliance installed on networks between a lan and a wan box would the qos policies be carried across wan end points (point to point connection)? In other words, will the router retain the TOS bits across to the other side of the wan connection to provide QoS-style priority for the packets or will it clear the TOS bits? BTW, the other side of the wan connection also has the qos appliance sitting between a lan and a wan box. Just so that I'm clear, I'm not talking about an upstream neighbor being an ISP connection which I know they will likely ignore the TOS bits unless I pay them extra for the feature. The above scenario is a point to point connection to a remote site. Any insight will be appreciated. regards, /vicky
The answer is it depends. routers _usually_ honor the TOS bits unless they are configured to clear or rewrite them. We use the TOS bits for designating traffic classes so in some cases we rewrite the TOS bits set by the host so in your case we would modify the TOS bits. Scott C. McGrath On Mon, 10 May 2004, Vicky Rode wrote:
Hi there,
Say if I had a qos appliance installed on networks between a lan and a wan box would the qos policies be carried across wan end points (point to point connection)? In other words, will the router retain the TOS bits across to the other side of the wan connection to provide QoS-style priority for the packets or will it clear the TOS bits? BTW, the other side of the wan connection also has the qos appliance sitting between a lan and a wan box.
Just so that I'm clear, I'm not talking about an upstream neighbor being an ISP connection which I know they will likely ignore the TOS bits unless I pay them extra for the feature. The above scenario is a point to point connection to a remote site.
Any insight will be appreciated.
regards, /vicky
Hi, Do you know by default if the routers pass the TOS bits? regards, /vicky Scott McGrath wrote:
The answer is it depends. routers _usually_ honor the TOS bits unless they are configured to clear or rewrite them. We use the TOS bits for designating traffic classes so in some cases we rewrite the TOS bits set by the host so in your case we would modify the TOS bits.
Scott C. McGrath
On Mon, 10 May 2004, Vicky Rode wrote:
Hi there,
Say if I had a qos appliance installed on networks between a lan and a wan box would the qos policies be carried across wan end points (point to point connection)? In other words, will the router retain the TOS bits across to the other side of the wan connection to provide QoS-style priority for the packets or will it clear the TOS bits? BTW, the other side of the wan connection also has the qos appliance sitting between a lan and a wan box.
Just so that I'm clear, I'm not talking about an upstream neighbor being an ISP connection which I know they will likely ignore the TOS bits unless I pay them extra for the feature. The above scenario is a point to point connection to a remote site.
Any insight will be appreciated.
regards, /vicky
Cisco and Enterasys definitely pass the TOS bits by default. You need to talk to your engineering group to see whether it is your site's policy to propagate TOS bits to make sure the TOS bits set by your appliance will arrive at their destination. Scott C. McGrath On Mon, 10 May 2004, Vicky Rode wrote:
Hi,
Do you know by default if the routers pass the TOS bits?
regards, /vicky
Scott McGrath wrote:
The answer is it depends. routers _usually_ honor the TOS bits unless they are configured to clear or rewrite them. We use the TOS bits for designating traffic classes so in some cases we rewrite the TOS bits set by the host so in your case we would modify the TOS bits.
Scott C. McGrath
On Mon, 10 May 2004, Vicky Rode wrote:
Hi there,
Say if I had a qos appliance installed on networks between a lan and a wan box would the qos policies be carried across wan end points (point to point connection)? In other words, will the router retain the TOS bits across to the other side of the wan connection to provide QoS-style priority for the packets or will it clear the TOS bits? BTW, the other side of the wan connection also has the qos appliance sitting between a lan and a wan box.
Just so that I'm clear, I'm not talking about an upstream neighbor being an ISP connection which I know they will likely ignore the TOS bits unless I pay them extra for the feature. The above scenario is a point to point connection to a remote site.
Any insight will be appreciated.
regards, /vicky
On 10-mei-04, at 18:57, Vicky Rode wrote:
Say if I had a qos appliance installed on networks between a lan and a wan box would the qos policies be carried across wan end points (point to point connection)? In other words, will the router retain the TOS bits across to the other side of the wan connection to provide QoS-style priority for the packets or will it clear the TOS bits?
First of all, most routers that apply quality of service mechanisms don't set the type of service in the process. However, many can use the type of service as input for their QoS decisions. Second, routers generally pass these bits unmodified, unless specifically instructed to change them. Third, these bits are often interpreted as a diffserv code point rather than the original type of service meaning. One setup I've used myself is set the type of service selectively using a rate limit on a Cisco router, and then do traffic shaping for packets matching this type of service on another router. AFAIK this isn't a particular common setup, though.
participants (3)
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Iljitsch van Beijnum -
Scott McGrath -
Vicky Rode