RE: How CIR behaviour in contention works for bit stream 2 and 3 Bit streams 2 and 3 define a CIR component which is incremented in 2.5 meg chunks. The default value is 2.5 meg CIR. In order to use this high priority queue the RSP must tag their layer 2 frames with P-bit 4. All other p-bits are remarked to 0--as per the TCF requirement. If a services exceeds the allocated CIR, those frames delivered outside of the policy will be discarded. That is anything over the CIR is dumped. From a end-user perspective, if all traffic was tagged high priority, then any excess over 2.5 would be randomly dropped and the customer would never experience the advertised 10m up / 30m down (low priority). Bit stream 3a is being designed to allow some excess to be used where frames out of policy will be tagged discard eligible, but not immediately discarded. Remember that Chorus has created labs in Auckland and Wellington which are open to Retail Service Providers so that services parameters appropriate to the applications that RSPs want to sell can be developed. The feedback from these labs needs to get to the TCF and CFH so any new products can be ratified by the industry. Curtis Owings Principal Solution Architect T +64 4 498 9355 (extn 49355) M +64 27 655 5335 E Curtis.Owings(a)chorus.co.nz Level 3, Deloitte House, 10 Brandon Street P O Box 632, Wellington www.chorus.co.nz P Please consider the environment before printing this e-mail ________________________________ This communication, including any attachments, is confidential. If you are not the intended recipient, you should not read it - please contact me immediately, destroy it, and do not copy or use any part of this communication or disclose anything about it. Thank you. Please note that this communication does not designate an information system for the purposes of the Electronic Transactions Act 2002.
Hi Curtis, Thanks for the great explanation. Just one question. The following two sentences *seem* to contradict each other.
If a services exceeds the allocated CIR, those frames delivered outside of the policy will be discarded.
then any excess over 2.5 would be randomly dropped
Can you confirm if OOP frames are all discarded, or randomly dropped. Cheers, Dean
On 5/06/12 11:24 AM, "Dean Pemberton"
Hi Curtis,
Thanks for the great explanation. Just one question. The following two sentences *seem* to contradict each other.
If a services exceeds the allocated CIR, those frames delivered outside of the policy will be discarded.
then any excess over 2.5 would be randomly dropped
Can you confirm if OOP frames are all discarded, or randomly dropped.
Cheers, Dean
From the TCF standard document: 6.7 Bandwidth and Colour marking
High Priority traffic will be policed up to a Committed Information Rate (CIR) and Committed burst Size (CBS) of the Ethernet Access service and classified as GREEN (Refer to MEF 23 for information on colour information). The Access Provider will deliver all GREEN traffic within the specified performance metrics. Any traffic that the Access Seeker marks as high priority but is above CIR will be classified as RED and discarded. Low priority traffic will be policed up to the Excess Information Rate (EIR) and Excess Burst Size (EBS) of the ELA service and marked YELLOW. The Access Provider should deliver YELLOW traffic if there is sufficient capacity in the network. Any traffic that the Access Seeker marks as low priority but is above EIR will be marked RED and discarded. *** Notice that word, "policed". If you find a frame that is OOP, drop it, instantly. Don't delay it, mull it over or try to be smart. Really, DON'T be smart. See also: 8.1 Traffic Management and Security, General principles All traffic in the Access Provider network flows either from UNI to E-NNI or from E-NNI to UNI. Direct UNI to UNI traffic is outside the scope of this document as is E-NNI to E-NNI traffic (i.e. between one Access Seeker and another Access Seeker). The Access Provider must, as far as possible, be entirely neutral with respect to the traffic it carries, i.e. the Access Provider, as a Layer 2 carrier shall not inspect the contents of the Access Seekers' End-users¹ unless it is necessary to do so to deliver IGMP snooping, and Lawful Intercept. All invalid traffic must be silently dropped as soon as it is detected. Invalid traffic refers to frames with invalid FCS, destination or source address, short frames or long frames. *** Don't try to second guess the access seeker. You have no way to tell that a frame is VoIP, or TCP, or anything. -- Michael Newbery IP Architect TelstraClear Limited Tel: +64-4-920 3102 Mobile: +64-29-920 3102 Fax: +64-4-920 3361 TelstraClear. Simple Solutions. Everyday Residential 0508 888 800 Business 0508 555 500 Enterprise & Government 0508 400 300 This email contains information which may be confidential and subject to copyright. If you are not the intended recipient you must not use, distribute or copy this email or attachments. If you have received this email in error please notify us immediately by return email and delete this email and any attachments. TelstraClear Limited accepts no responsibility for changes made to this email or to any attachments after transmission from TelstraClear Limited. It is your responsibility to check this email and any attachments for viruses. Emails are not secure. They can be intercepted, amended, lost or destroyed and may contain viruses. Anyone who communicates with TelstraClear Limited by email is taken to accept these risks.
participants (3)
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Curtis Owings -
Dean Pemberton -
Michael NEWBERY