SpawnPoint

So.. a blog entry without a cause huh?  Almost sounds like a cause for alarm.  Hmm.. What to blog about...  *looks around*  Ooh Networking!  Yeah.  I mean networking is pretty cool, and while I did talk about it a bit in my last post, it's just that I have a network diagram posted above my laptop here on the wall with black electricians tape.  Heh.  My current arch enemy?  QOS.  I don't really understand it very well, and it's causing me a bunch of problems.  Stupid quality of service.  Yup.  Mini Rant on QOS.  Hmm.. Wonder if I should change the blog title then... eh, na.

Toph @ 2007-06-19 00:31:06
Quality of Service is a lot like Hitman. It tells certain packets to xxxx right off, so that other packets can go on their marry way faster.

.. yeah, that's my extent of understanding QoS.

/toph

weaver @ 2007-06-19 08:33:56
Because I am your friend..

http://en.wikipedia.org/wiki/Qos

Quality of service, or QoS, in the field of telephony, was defined in the ITU standard X.902 as "A set of quality requirements on the collective behavior of one or more objects."

In the fields of packet-switched networks and computer networking, the traffic engineering term Quality of Service refers to control mechanisms that can provide different priority to different users or data flows, or guarantee a certain level of performance to a data flow in accordance with requests from the application program or the internet service provider policy. Quality of Service guarantees are important if the network capacity is limited, for example in cellular datacommunication, especially for real-time streaming multimedia applications, for example voice over IP and IP-TV, since these often require fixed bit rate and may be delay sensitive.

A network or protocol that supports Quality of Service may agree on a traffic contract with the application software and reserve capacity in the network nodes during a session establishment phase. During the session it may monitor the achieved level of performance, for example the data rate and delay, and dynamically control scheduling priorities in the network nodes. It may release the reserved capacity during a tear down phase.

A best-effort network or service does not support Quality of Service.

The term Quality of Service is sometimes used as a quality measure with many alternative definitions, rather than referring to control mechanisms. A good QoS may mean advanced QoS control mechanisms, or high probability that the network is able to live up to the contract or provide the requested level of performance. High QoS is often confused with a high level of performance, for example high bit rate, low latency and low bit error probability. See also Relation to subjective quality measures below.

Chareon @ 2007-06-29 07:30:48
Yeah, the base concept of QoS is ok, it's when you start trying to do funky stuff like below with DSCP mutation and the such. (Sadly this is actually a semi easy example of QoS, some stuff is alot harder.)

mls qos map dscp-mutation MUTATE 0 1 2 3 4 5 6 7 to 10
mls qos map dscp-mutation MUTATE 8 9 11 12 13 14 15 to 10
mls qos map dscp-mutation MUTATE 16 17 18 19 21 22 23 24 to 20
mls qos map dscp-mutation MUTATE 25 26 27 28 29 30 31 to 20
mls qos map dscp-mutation MUTATE 32 33 34 35 36 37 38 39 to 30
mls qos map dscp-mutation MUTATE 40 41 42 43 44 45 46 47 to 30
mls qos map dscp-mutation MUTATE 48 49 50 51 52 53 54 55 to 40
mls qos srr-queue input bandwidth 70 30
mls qos srr-queue input threshold 1 55 75
mls qos srr-queue input threshold 2 55 75
mls qos srr-queue input buffers 70 30
mls qos srr-queue input dscp-map queue 1 threshold 2 20
mls qos srr-queue input dscp-map queue 2 threshold 1 30
mls qos srr-queue input dscp-map queue 2 threshold 2 40
mls qos
!
class-map match-all cmFA10
match input-interface FastEthernet0/10
class-map match-all cmFA11
match input-interface FastEthernet0/11
class-map match-all cmVLAN120
match access-group name QOSACL1
!
interface FastEthernet0/1
switchport access vlan 110
switchport mode access
mls qos trust dscp
mls qos dscp-mutation MUTATE
!
interface FastEthernet0/10
switchport access vlan 120
switchport mode access
mls qos vlan-based
!
interface FastEthernet0/11
switchport access vlan 120
switchport mode access
mls qos vlan-based
!
interface Vlan120
no ip address
service-policy input pmVLAN120
!
ip access-list extended QOSACL1
permit ip any host 10.0.0.120

Streetbum @ 2007-06-29 11:11:25
My head just exploded......

Chareon @ 2007-06-29 20:42:02
Yeah, well it.. WAS nicely formatted till the comment monster got it and removed breaks. :P It's a bit easier to understand when it isn't a big mess, but even still.

Chareon @ 2007-06-29 20:46:07
Ok. Added a page to my blog so that you can see it all formatted. I didn't remove the portions that arn't QoS, but that's probably better as you can see what else is configured. (Not alot, as that switch didn't do anything other than QoS really.)

http://chareon.spawnpoint.com/pages.php?pageid=334