QoS for 3750 for single IP?

[Christie Brinker]

                   Hello all,

I have a Catalyst 3750 that is connected via a point to point fiber connection to another location that has another Catalyst on the other end. At this remote location is a server that replicates data to a server on my end. I would like to find a way to control how much bandwidth these two servers can use when they replicate. Is there a way to enable QoS on the 3750 using an IP address or ACL and it hit all traffic for that IP? The examples I have researched generally use a dscp setting so I was a little lost.

Thanks!

[paul driver]

Hello

You can police traffic from  host to host using a acl or mark traffic from each server and police on those marked values.

Switch A for server B

access-list 100 permit ip host (serverA host (serverB)

access-list 100 permit ip host (serverB host (serverA)

conf t

mls qos

class-map ServerB

match access-group 100

Policy-map ServerB_pm

class ServerB

police 1000000 31250 exceed-action drop

int x/x (SwitchA trunk port )

serivce-policy input ServerB_pm

Switch B for server A

access-list 100 permit ip host (serverB host (serverA)

access-list 100 permit ip host (serverA host (serverB)

conf t

mls qos

class-map ServerA

match access-group 100

Policy-map ServerA_pm

class ServerA

police 1000000 31250 exceed-action drop

int x/x (SwitchB trunk port )

serivce-policy input ServerA_pm

res

Paul

Please don't forget to rate any posts that have been helpful.

Thanks.

[Joseph W. Doherty]

Disclaimer

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Posting

Christie, perhaps the easiest method is the one shown by Paul, policing your replication traffic to some defined rate.  However, possibly a better method is to use relative priorities.  What you can do is direct your replication traffic into a dedicated egress queue with a (very) low bandwidth allocation relative to all your other traffic (or conversely direct all your other traffic to a dedicated queue with PQ configured - this should work very well, but complicates possible future QoS usage).  The advantage of the prioritization techniques vs. policing, your replication traffic could use all the link's available bandwidth but would basically allow your other traffic to use that link's bandwidth first.

[Christie Brinker]

I like the way that sounds JosephDoherty.

My question is, is this port based as well? The above example looks as though I have to have the servers plugged directly into the switch that has QoS configured.

[Joseph W. Doherty]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

Policing on the 3750, if I remember correctly, can only be done on ingress (port or VLAN).  However, if you have more than one switch, a later switch can examine its ingress traffic and selectively police.

Prioritization is done on port egress, however you cannot have a policy to select which queue traffic is directed to.  For egress traffic you need to rely on either L2 CoS or L3 ToS markings.  Those are either set by the host, itself, or they might be set within an ingress policy.

[Christie Brinker]

Let me just make sure I am thinking on the same page.

I have a Catalyst 2960S, unforunately it's LAN Base. Can I use this switch to "tag" the traffic for a server that is plugged into it and then have the 3750 police the traffic for this IP?

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Without some research, don't know what the tagging features are of the 2960-S.

As I described in my earlier posting, the 3750 can police ingress traffic.  On a port it could selectively match against a tag and/or an IP.

What I didn't mention, the 3750 supports per egress queue shaping too.  So if your IP addressed packets are tagged, you can direct those packets to a set aside egress queue that shaped.  I mention this incase you wanted to shape rather than police this traffic.