Thank you. It's clear for me now. >with IP Prec or DiffServ (which one is it?) IP precedence (3 bits), for layer 3 Priority for layer 2.
Teresa ----- Original Message ----- From: Steven A. Ridder To: [EMAIL PROTECTED] Sent: Monday, March 04, 2002 9:19 PM Subject: Re: read and not write TOS [7:36946] I'm pretty good with QOS. If you connect your special switch to a router and you mark your packets with IP Prec or DiffServ (which one is it?) your packet will remain marked until they reach the destination. The only time you would lose these markings is if a router is programmed to strip the markings and replace them with something else. As for your CoS bits, they will be fine until they hit a layer 3 device. If they remain on a large flat L2 network, then they will remain untouched. If the packets have to go through a router of some sort (because they need to be routed to a different network) the L3 device will strip the layer 2 ethernet packet, replace them with it's own l2 packet based on what type of link it's going out of (PPP, HDLC, another ethernet netowrk) and send it on it's merry way. Unfortuately, that L2 packet had your 802.1p bits in it and it was trashed. So you lost them (unless you have the router map l2 to l3). Therefore, it's better to just mark L3. Finally, just because you mark your packets, doesn't mean you'll get any special treatment unles the routers are told to do so (unless you have WFQ enabled on the router, as WFQ automatically classifies based on IP Prec or DiffServ.). Look up MQC to create policies to do things with your marked packets. -- RFC 1149 Compliant. ""TP"" wrote in message news:[EMAIL PROTECTED].; > I said "special switch": it is a switch with ethernet ports and voice ports, > with the voice processor and its stack. > So, I can program the "special switch" in order to set the TOS (layer 3) per > port basis and the COS (layer 2) per port basis. > What happens to my packet (or frames) when I connect this switch to a router > (827 per adsl) or to a layer 3 catalyst for different design? > > > ----- Original Message ----- > From: [EMAIL PROTECTED] > To: [EMAIL PROTECTED] > Sent: Friday, March 01, 2002 6:05 PM > Subject: Re: read and not write TOS [7:36946] > > > I don't think you can set the ToS bits on a switch. You can only set the > CoS bit and the CoS will not be translated to a ToS on router unless you > force it to in the configuration. ToS is a layer 3 function and CoS is a > layer 2 function > > > >From: "TP" > >Reply-To: "TP" > >To: [EMAIL PROTECTED] > >Subject: read and not write TOS [7:36946] > >Date: Fri, 1 Mar 2002 06:14:30 -0500 > > > >Dear group, > >i have the following situation: > >a "special" switch connected to a cisco router via ethernet interface. > >This switch is enable to set TOS based on its ports. > >I'd like to configure the router in order to have different queuing based > >on > >the TOS (two or three queues). > >The router should read (and NOT write) the TOS and priorituze the > traffic > >with the higher TOS: is it possible? If yes, maybe with access-list or > >samething different, can you provide the proper command lines? > >Thanks in advance > >Teresa > _________________________________________________________________ > MSN Photos is the easiest way to share and print your photos: > http://photos.msn.com/support/worldwide.aspx Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=37241&t=36946 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
