From: GAURAV MADAN (gauravmadan1177@gmail.com)
Date: Fri Sep 19 2008 - 16:18:54 ART
Hi Petr
Continuing with that .... can you please tell what task " ip tcp ecn
" perform at the end devices .
I guess this is more to do with the device in middle informing the end
devices abt the congestion . Can you please tell more abt usage of
this ?
Thnx
Gaurav Madan
On Fri, Sep 19, 2008 at 11:08 PM, Petr Lapukhov
<petr@internetworkexpert.com> wrote:
> Igor,
> Those are actually "different" ECN technologies. The first one
> ("random-detect ECN") works with TCP and WRED. Instead of randomly dropping
> packets, scheduler sets ECN bits in IP header ToS byte, signaling
> ECN-capable endpoints to respond to network congestion. This feature works
> specifically with TCP and congesting management based on WRED.
>
> The last two have to deal with Frame-Relay ECN signaling. Those are used in
> Frame-Relay switching code and apply to switched PVCs crossing a particular
> DCE interface.
>
> The command "frame-relay congestion-management threshold ecn {bc|be}
> <THRESHOLD%>" instructs router to monitor interface output queue. If the
> queue depth grows above the configured "ECN Be" threshold percentage, then
> the router sets BECN/FECN bits in all input/output Frame-Relay packets
> marked with DE bit. However, if the queue depth climbs above "ECN Bc"
> threshold, then the router adds ECN bits to ALL packets (either DE and
> non-DE marked). Note that this feature is "interface-wide" and affects all
> PVCs.
>
> You may also enable ECN thresholding on PVC shaping queue, by applying the
> command "frame-relay congestion threshold ecn" under a "map-class
> frame-relay" for a specific PVC. This feature monitor the specific PVC
> software queue, not the shared interface queue. The procedure makes ECN
> marking "PVC specific" and aware of "per-VC" congestion state.
>
> In addition to ECN signaling thresholds in Frame-Relay networks, you may
> also configure "DE-bit" threshold that specifies the level of queue depth
> where router starts dropping DE-marked packets.
>
> All the above mentioned features are part of Frame-Relay adaptive congestion
> management. Generally speaking, those are SP related, and you dont have to
> deal with them in the R&S lab.
>
> HTH
>
> Further Reading:
> http://www.cisco.com/en/US/docs/ios/wan/configuration/guide/wan_cfg_frm_rly_ps6350_TSD_Products_Configuration_Guide_Chapter.html#wp1055798
>
> --
> Petr Lapukhov, CCIE #16379 (R&S/Security/SP/Voice)
> petr@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987
> Outside US: 775-826-4344
>
> 2008/9/18 Igor M. <imanassypov@rogers.com>
>
>> Hi gang,
>>
>> Anyone knows if there is a significant difference between following fr
>> congestion management tools?
>>
>> 1. under policy-map 'random-detect ecn'
>> 2. under pvc 'frame-relay congestion-management threshold ecn 75'
>> 3. under fr map-class 'frame-relay congestion threshold ecn 75'
>>
>> From what I understand, 2 & 3 would be legacy and 1 comes from MQC. But
>> functionally-wise - are they same or different?
>>
>> Thanks
>>
>> ----------------------
>>
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>>
>> Network Architect
>>
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