Subject: RE: Traffic Shaping for Multicast flows

From: Andrew Smith <[email-masked]>
Date: Tue, 18 Feb 1997 13:49:40 -0800

>----------
>From: 	Ashish Mehra[SMTP:[email-masked]]
>Sent: 	Tuesday, February 18, 1997 10:14 AM
>To: 	[email-masked]
>Cc: 	[email-masked]; [email-masked]
>Subject: 	Re: Traffic Shaping for Multicast flows
>...
>Even without the above scenario, the main point of my comments 
>was to highlight OS-related overheads that may limited scalability
>even at routers, especially if traffic is shaped via OS timers.
>It is important to note again that routers may need to perform
>reshaping even when the traffic specification at the host is not
>violated, i.e., could occur with sufficient frequency to make 
>it an important issue. Perhaps it is not an issue at backbone 
>routers - I would appreciate if you (or someone) can clarify what 
>mechanisms routers rely on to realize shaping. 

I think it will have to be transistor-based mechanisms, rather
than "OS timers" (note the future tense here).
>Ashish

Andrew

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>Andrew Smith                                    tel: +1 (408) 342-0985
>Extreme Networks                                fax: +1 (408) 342-0990
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>Cupertino CA 95014                              em:
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---

From: Ashish Mehra <[email-masked]>
Date: Tue, 18 Feb 1997 17:22:01 -0500 (EST)

> than "OS timers" (note the future tense here).

I tend to agree with that, especially in the light of IP 
switching solutions being worked upon. Also, there has 
been a fair bit of work in the ATM switch 
design/implementation arena that has looked into similar 
issues, including efficient calendar queue implementations 
and flow grouping. Note that server networking software 
may still need to rely upon OS timers, unless (non-ATM)
adapters are equipped with sufficient intelligence.

I agree with Craig that it depends largely on the 
implementation. And I do believe that some form of 
aggregated traffic shaping will be useful both at routers 
and hosts.

Ashish