QoS - Shaping

rakem

Can I setup a lab to test some shaping policies if it is connected like;

3560

---

Router

---

3560

or for shaping to working correctly would it need to be;

3560

---

router

---

router

---

3560

I'm thinking the seccond option, as the link between the router simulates the WAN link which is where shaping would be applied.

Since the 3560s only do policing I don't think shaping would work correctly in the first config...
thoughts?

EdTheLad

You could shape on the egress router interface on the first setup.On the 3560 place an ingress policy map with classes to match the incoming flows and just do a "show policy-map interface x/x" to verify the incoming rate is shaped as expected.

rakem

Traffic comming from the 3560 wouldn't be shapped then.... It would only get shapped on the egress of the router,

ColbyG

rakem wrote: »

Traffic comming from the 3560 wouldn't be shapped then.... It would only get shapped on the egress of the router,

Isn't that enough to test what you're trying to test?

kryolla

If you want to do traffic shaping on the router than either lab will work. Shaping is only done outbound so depending on traffic flow you can configure it on both interfaces on the router. To shape for the 3560 look into this command srr-queue bandwidth shape

rakem

ColbyNA wrote: »

Isn't that enough to test what you're trying to test?

I would like to be able to shape accross the whole connection. Trying to simulate synchronus connections (512/512 or 1024/1024)

kryolla wrote: »

If you want to do traffic shaping on the router than either lab will work. Shaping is only done outbound so depending on traffic flow you can configure it on both interfaces on the router. To shape for the 3560 look into this command srr-queue bandwidth shape

The issue with 3560

---

router

---

3560 is that if traffic is sent from a node connected to the 3560 on the left, it will go at 100Mb until it leaves the router. I'd like it to go at 512 from the moment it hits the router.... so with 3560----router

---

router----3560 traffic would be 100Mb to the first router then be shaped until it hits the 3560 on the right.

I have used srr-queue bandwidth limit [interface percentage] before on a 3560 to achieve shaping. But doing it this way i had to hard code the port to 10Mb, then limit it to 10% (which is the lowest value)

I never had much luck getting srr-queue bandwidth shape command working. I understand you enter the bandwidth weight for each queue but couldn't figure out what values to enter to achieve the results i wanted

kalebksp

You cannot shape on ingress interfaces, only police. Both setups do essentially the same thing, one just has another router in the path.

kryolla

I'd like it to go at 512 from the moment it hits the router

look into policing then for ingress but it will drop traffic above this which is okay for TCP as it will retrans

rakem

ok so say i have this

3560A

---

router1

---

3560B

---

router2

---

3560C

if i'm sending traffic from 3560A to 3560C, and put a 512k shaping policy outbound on R1, will the traffic stay at the shaped rate as it passes through 3560C and Router2.

(Router2 would also have the 512k shaping policy on its egress interface to 3560C)

kryolla

rakem wrote: »

ok so say i have this

3560A

---

router1

---

3560B

---

router2

---

3560C

if i'm sending traffic from 3560A to 3560C, and put a 512k shaping policy outbound on R1, will the traffic stay at the shaped rate as it passes through 3560C and Router2.

(Router2 would also have the 512k shaping policy on its egress interface to 3560C)

your bandwidth is only as fast as your slowest link so I would have to say yes with everything else being equal

cisco_trooper

Good old QoS. It seems there is always something to learn with QoS and not enough equipment to learn it all.

EdTheLad

rakem wrote: »

ok so say i have this

3560A

---

router1

---

3560B

---

router2

---

3560C

if i'm sending traffic from 3560A to 3560C, and put a 512k shaping policy outbound on R1, will the traffic stay at the shaped rate as it passes through 3560C and Router2.

(Router2 would also have the 512k shaping policy on its egress interface to 3560C)

Shaping will only occur on the egress interface of R1 if the interface is under congestion or the output rate is higher than 512k.You cannot guarantee the traffic rate downstream if your qos policy isn't consistent.If for instance you had no traffic policy on R2 and the egress interface to 3560C was congested due to an unaccounted flow, you would not be able to guarantee that the scheduler on R2 would not send bursts to 3560c larger than the required 512K.
If you are looking at this without outside influences, then yes you should be sure the traffic exiting R2 will be at the configured shaped rate or below.