All things related to multicast

["Marshall Eubanks" <>]

On Mon, 13 May 2002 07:55:21 -0700 (PDT)
 "Lucy E. Lynch" 
<>
 wrote:
> Bill -
> 

Hello;

   MSDP had a limit of ~ 1500 bytes (1492, I think), that was extended to

"The maximum size SA message that can be sent is 9192 octets. The 9192
   octet size does not include the TCP, IP, layer-2 headers."

in version 12 of the MSDP draft. 
The idea was to fit in ethernets, and then into
SONET. There is no provision for fragmentation. Since SAP is largely carried
encapsulated in MSDP, this sets an effective limit on the size of SAP packets.

> Additional testing on our end (thanks to Jon Miyake) shows that
> any large announcement will break both SDR & XMIM (info field,

Was this > 1492 bytes ? > 9192 bytes ? At least 1492 should be supported.

Marshall

> subject field etc.) and it appears that this is related to
> the strong suggestion in the RFC:
> 
> RFC 2974             Session Announcement Protocol          October 2000
> 
>    RECOMMENDED that SAP packets are smaller than 1kByte in length,
>    although if it is known that announcements will use a network with a
>    smaller MTU than this, then that SHOULD be used as the maximum
>    recommended packet size
> 
> Not sure if IP/TV & VBrick have the same limitations built in.
> 
> Lucy E. Lynch                                 Academic User Services
> Computing Center                      University of Oregon
> 
>               (541) 346-1774/Cell: 912-7998
> 
> On Mon, 13 May 2002, Bill Owens wrote:
> 
> > At 11:07 -0700 5/10/02, Lucy E. Lynch wrote:
> > >James -
> > >
> > >I'm using both SDR v2.8 and xmim (see:http://videolab.uoregon.edu/mim/)
> > >to try and gather sap announcements on a linux box (redhat 7.1) -
> > >XMIM will collect announcements for a while and then seg faults -
> > >while sdr manages to collect announcements and stay up - but if I
> > >exit and then re-start it dumps core.
> >
> > I have seen the same symptoms here, with SDR 2.8. I am also running
> > the sdr-monitor TCL script, I'm not sure if that makes any difference.
> >
> > BTW, the University at Buffalo did not have multicast connectivity
> > until very recently, April 25 to be exact. Prior to that date Jim was
> > presumably running this session unicast, or with a point-to-point
> > tunnel that didn't touch the MBONE.
> >
> > Bill.
> >
>