All things related to multicast

[Paul Chang <>]

Thanks to everyone about the suggestion regarding mcast rate limit 
option at SUP720.

I have set up the followings to protect the control plan but feel this 
still a trial and error situation depending on type of applications the 
switch serves since the rate can varies as <10-1000000>  packets per second

mls rate-limit multicast ipv4 fib-miss 3000 100
mls rate-limit multicast ipv4 connected 3000 100
mls rate-limit multicast ipv4 ip-options 3000 100
mls rate-limit multicast ipv4 partial 3000 100
mls rate-limit all ttl-failure 2000 10

A quick poll for site running AccessGrid application, what is the 
optimal number you use without sacrifice performance?

Suggestions or comments will be greatly appreciated.

- Paul C.






Stig Venaas wrote:

> Paul Chang wrote:
>
> > Folks,
> >
> > Anyone has similar problem on this?
> >
> > When Powerquest drivemage set TTL=1, the nearest L3 switch (6513 in 
> > this case) has CPU utilization goes beyond 98%. If I adjusted the 
> > TTL=x to match how many hop the RP is, both the nearest L3 switch and 
> > RP has high CPU utilzation goes beyond 90%. The switch did not die in 
> > this case, but all software relate process were crawling.
>
>
> There was a mail regarding this sent to the list by Brian Field in 
> February. He wrote:
>
> > Re hardware rate limiting of TTL=1 on the sup 720, check out
> > "mls rate-limit all ttl-failure pps burst". Note that this
> > applies to both multicast and unicast traffic.
> >
> > There are a number of other handy multicast specific hardware
> > rate limiters under "mls rate-limit multicast".
>
> This is for 6509 with sup720, but is probably valid for some other 
> systems (at least recent ones, not older supervisors).
>
> You may also see
> http://www.cisco.com/en/US/partner/products/hw/switches/ps708/products_tech_note09186a00804916e0.shtml 
>
>
> Stig
>
> > My work-around is to turn off the "ip PIM sparse-mode" at the vlan 
> > where Mcast source and destinations are taken place (all within on 
> > vlan). This works fine since L2 Cisco 35xx has IGMP-snooping turned 
> > on. Usually, 1 /40 source/destination ratio for computer lab imaging 
> > building is conducted.
> >
> > I have Cisco TAC given me the followings
> >
> > http://www.cisco.com/en/US/products/hw/switches/ps708/products_white_paper0900aecd802ca5d6.shtml 
> >
> >
> > Some data-plane traffic may have to be processed in software as well. 
> > This type of traffic is referred to as data-plane "punt" traffic. 
> > Examples of software-processed data-plane packets include:
> >
> > • Packets with IP options
> >
> > • Packets with time-to-live (TTL) field equal to 1
> >
> >
> > which looks to me a design flaw of the control plane.
> >
> > Anyone has a better way to deal with this? Please advice,
> >
> > P a u l C h a n g Network Engineer
> > University of New Mexico
> > Computer & Information Resources & Technology
> > 2701 Campus Boulevard NE, Albuquerque, NM 87131
> > Phone: (505) 277-8257 FAX: (505) 277-8101