what is CoS and ToS?

[ashley9march]

Hi friends,

I need your assistance, hope you won't let me down.

Please explain me , what is CoS and What is ToS adn what is the role of ip precedence along with them. And what is the best end to end solution for the voice? How ToS and CoS work?

[spremkumar]

Hi

AFAIK its been called as COS in L2 Scenario/Toplogy and in L3 its called as TOS.

We normally do marking using either COS or TOS which is used to differentiate between the normal and prioritized traffic patterns.

IP Precedence falls into TOS it uses the 3 bit field of TOS bits to do the necessary marking / classifcation.

using that 3 bits you can have 8 (0 to 7) different class of traffics configured in your network.

And in recent times DSCP has suceeded over IP precedence value and u got to have 64 different classess (0 to 63) with that.

i feel you startup your configs keeping DSCP in mind and also the link attached for more info.

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a00800dc04c.html

Do keep in mind that the QOS configs to be present in all the transit equipements(routers) as well to have the advantage of configuring the same..

regds