[nsp] Multicast Ghost

Cheung, Rick Rick.Cheung@NextelPartners.com
Tue, 5 Nov 2002 16:25:34 -0600


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	Thanks Tony.

	We've enabled CGMP on the router's ethernet interfaces, and its on
by default on the switches.

	We still see problems with two of our large sites though. However,
one of these large sites has 2 4006s with the L3 card forming the core, and
the CPU was at 92% over 5 minutes.

	I tested this further today, with an office that had 2 2600 routers,
1 Frac T1 each, and there were no noticable impact to the network. The
fas0/0 was taking in around 10-20mbps, and the CPU was at 60% over a 5
second interval.

	I wonder if its a problem with process switching on the L3 card? 



Rick Cheung
NPI IT Wan Team, CCNP


-----Original Message-----
From: Tony Wasson [mailto:ajwasson@inficad.com]
Sent: Tuesday, November 05, 2002 4:10 PM
To: Cheung, Rick; cisco-nsp@puck.nether.net
Subject: Re: [nsp] Multicast Ghost
Importance: High


> Hi, I'd like to see if anyone else is seeing the same problems with
> ghost multicast 7.5 that I'm seeing.
>
> We run ghost multicast to image workstations without a problem in
> sites that are served by a 2620, with a fractional T to the datacenter.

I have not seen the bugs you are describing, but I will tell you my run in
and work around for multicast Ghost on an Ethernet/IP network.
We had 100Mbps Ghost Multicasts that melted our switched network before
anyone had turned on IGMP. So we turned on IGMP and filtered the default
G.S.T. Multicast MAC address in our our WAN Edge switches. You could do this
at each edge router if your switches can't drop traffic by MAC address.


http://www.dante.net/nep/GEANT-MULTICAST/deployment-msdp.html
lists the GHOST Default IP as 229.55.150.208/32
http://www.hep.ucl.ac.uk/~ytl/multi-cast/addresstranslation_01.html
Quick (but possibly wrong) Multicast MAC should be: 00:00:5e:37:96:d0

Hope this helps,
Tony Wasson

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charset=3Diso-8859-1">
<META NAME=3D"Generator" CONTENT=3D"MS Exchange Server version =
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<TITLE>RE: [nsp] Multicast Ghost</TITLE>
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<BODY>

<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <FONT SIZE=3D2>Thanks =
Tony.</FONT>
</P>

<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <FONT SIZE=3D2>We've =
enabled CGMP on the router's ethernet interfaces, and its on by default =
on the switches.</FONT>
</P>

<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <FONT SIZE=3D2>We still =
see problems with two of our large sites though. However, one of these =
large sites has 2 4006s with the L3 card forming the core, and the CPU =
was at 92% over 5 minutes.</FONT></P>

<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <FONT SIZE=3D2>I tested =
this further today, with an office that had 2 2600 routers, 1 Frac T1 =
each, and there were no noticable impact to the network. The fas0/0 was =
taking in around 10-20mbps, and the CPU was at 60% over a 5 second =
interval.</FONT></P>

<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <FONT SIZE=3D2>I wonder =
if its a problem with process switching on the L3 card? </FONT>
</P>
<BR>
<BR>

<P><FONT SIZE=3D2>Rick Cheung</FONT>
<BR><FONT SIZE=3D2>NPI IT Wan Team, CCNP</FONT>
</P>
<BR>

<P><FONT SIZE=3D2>-----Original Message-----</FONT>
<BR><FONT SIZE=3D2>From: Tony Wasson [<A =
HREF=3D"mailto:ajwasson@inficad.com">mailto:ajwasson@inficad.com</A>]</F=
ONT>
<BR><FONT SIZE=3D2>Sent: Tuesday, November 05, 2002 4:10 PM</FONT>
<BR><FONT SIZE=3D2>To: Cheung, Rick; cisco-nsp@puck.nether.net</FONT>
<BR><FONT SIZE=3D2>Subject: Re: [nsp] Multicast Ghost</FONT>
<BR><FONT SIZE=3D2>Importance: High</FONT>
</P>
<BR>

<P><FONT SIZE=3D2>&gt; Hi, I'd like to see if anyone else is seeing the =
same problems with</FONT>
<BR><FONT SIZE=3D2>&gt; ghost multicast 7.5 that I'm seeing.</FONT>
<BR><FONT SIZE=3D2>&gt;</FONT>
<BR><FONT SIZE=3D2>&gt; We run ghost multicast to image workstations =
without a problem in</FONT>
<BR><FONT SIZE=3D2>&gt; sites that are served by a 2620, with a =
fractional T to the datacenter.</FONT>
</P>

<P><FONT SIZE=3D2>I have not seen the bugs you are describing, but I =
will tell you my run in</FONT>
<BR><FONT SIZE=3D2>and work around for multicast Ghost on an =
Ethernet/IP network.</FONT>
<BR><FONT SIZE=3D2>We had 100Mbps Ghost Multicasts that melted our =
switched network before</FONT>
<BR><FONT SIZE=3D2>anyone had turned on IGMP. So we turned on IGMP and =
filtered the default</FONT>
<BR><FONT SIZE=3D2>G.S.T. Multicast MAC address in our our WAN Edge =
switches. You could do this</FONT>
<BR><FONT SIZE=3D2>at each edge router if your switches can't drop =
traffic by MAC address.</FONT>
</P>
<BR>

<P><FONT SIZE=3D2><A =
HREF=3D"http://www.dante.net/nep/GEANT-MULTICAST/deployment-msdp.html" =
TARGET=3D"_blank">http://www.dante.net/nep/GEANT-MULTICAST/deployment-ms=
dp.html</A></FONT>
<BR><FONT SIZE=3D2>lists the GHOST Default IP as =
229.55.150.208/32</FONT>
<BR><FONT SIZE=3D2><A =
HREF=3D"http://www.hep.ucl.ac.uk/~ytl/multi-cast/addresstranslation_01.h=
tml" =
TARGET=3D"_blank">http://www.hep.ucl.ac.uk/~ytl/multi-cast/addresstransl=
ation_01.html</A></FONT>
<BR><FONT SIZE=3D2>Quick (but possibly wrong) Multicast MAC should be: =
00:00:5e:37:96:d0</FONT>
</P>

<P><FONT SIZE=3D2>Hope this helps,</FONT>
<BR><FONT SIZE=3D2>Tony Wasson</FONT>
</P>

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