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Posted by vicky on June 20, 2008, 12:04 am
wrote:
> In article
>
> > Hi,
>
> > =A0 =A0 =A0 =A0Plz explain =A0...
>
> > =A0 =A0 =A0 =A0 A single mac address is able to be a member of multiple=
vlans.
>
> A MAC address is not a "member" of a VLAN. It is *frames* (not MAC
> addresses, ports, IP addresses, or anything else) that are associated
> with particular VLANs. The rules for associating frames with VLANs can
> be based on almost any characteristic of the frame, such as:
>
> -the switch port on which the frame arrived (port-based VLAN)
> -the MAC source address in the frame (MAC address-based VLAN)
> -the IP subnet identifier within the frame (IP subnet-based VLAN)
> -the TCP/UDP port number within the frame (application-based VLAN), etc.
>
> While many people may *think* they are associating a port (or a MAC
> address) with a VLAN, they are really specifying a VLAN-association rule
> that is based on switch port (or MAC address); the distinction is
> subtle, but important, particularly when end stations are VLAN-aware,
> and perform the association themselves.
>
> Consider a multi-homed VLAN-aware end station (e.g., a server) that
> associates frames with VLANs based on IP subnet identifiers. Since that
> station has multiple IP addresses (that's what multi-homed means), it
> will emit frames carrying different VLAN IDs, depending on the subnet to
> which the frame is directed. However, that station may have the same MAC
> address on all subnets (sidebar: I never said that the server had
> multiple physical interfaces, and even if it did, it is permissible to
> assign the same MAC address to multiple interfaces that are not on the
> same LAN). Thus, this is a device that, according to *your* model, has a
> MAC address that is a "member" of multiple VLANs. This dichotomy
> disappears when one realizes that it is the *frames* that are associated
> with the VLANs, and each frame is associated with one (and only one)
> VLAN.
>
> If you don't like the multi-homed station example, the same phenomenon
> arises in the case of a single-homed station that associates VLAN IDs
> based on application streams; e.g., a video delivery server (think:
> Intranet multicast delivery of training videos) that assigns a VLAN to
> each video stream so that bandwidth can be conserved within an
> enterprise. Another example is a VoIP conference-call server,
> associating each conference call (multicast) to a VLAN.
>
> There is a complete explanation of this in Chapter 11 of "The Switch
> Book."
>
> --
> Rich Seifert =A0 =A0 =A0 =A0 =A0 =A0 =A0Networks and Communications Consu=
lting
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 21885 Bear Creek Way
> (408) 395-5700 =A0 =A0 =A0 =A0 =A0 =A0Los Gatos, CA 95033
> (408) 228-0803 FAX
>
> Send replies to: usenet at richseifert dot com
------------------------------------------------------------------
Sir ...
As u mentioned about a book .... The Switch Book...
can u plz ... give a full detail of this book (publication, writer
etc)
so that it is easy for me to find it at book stores....
Vikrant.
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