802.1 vLAN meeting, 3/12/96, 11:00am, LaJolla, Ca.
Embedded vLAN Tagging  (96/021)
2nd presentation, John Bartlett - Agile Networks
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Embedded vLAN Tagging

- Goal: Develop a tagging scheme for a backbone hierarchy that:
        -maintains vLAN indentification between vLAN aware switches
        -Uses currently defined MTU sizes
- Limitations
        -Requires vLAN aware switches in the backbone of the network
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vLAN Switch Hierarchy
(picture)  switch hierarchy ... vLAN aware Switch on top...

                                vLAN Challenged switch... on bottom...
- vLAN switches communicate with vLAN tagging scheme
- vLAN only propogate as far as there are vLAN aware switches
- vLAN aware switches must be contiguous
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- Problem:
        -How to communicate information within an MTU without losing information
-Opportunity:
        -MAC address information is not densely packed,
         i.e. there are <<2^48 end stations on this particular link
-Solution:
        -Recode the DA by commmon agreement between two switches
        -Include a field to indicate to which vLAN this packet belongs
        -Include a field to represent the original DA
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 Tagging Approach Example
 |   | 1 | VLAN OUI |  Instance ID |  VLAN OUI   |
 <----------------48 bit MAC--------------------->
        -Set local addressing bit
        -Assign vLAN OUI
        -12-bits of Instance ID
        -12 bits of vLAN ID

vLAN Table:                             Instance Table:
       | IP: red                        | xx:yy:zz:aa:bb:cc:dd:ee:f:gg:hh:kk
       | IPX: A.B.C>D                   |
vLAN ID| LAT7               Instance ID |
       | IP: blue                       |
       | Partition21                    |
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How to Establish the Tables
-Statically configured via administrative interface
        -Not acceptable because of lack of automation
-Dynamically configured by management station
        -Requires knowledge of each switch type in manager
        -Allows global optimization
        -Creates potentoal simgle point of failure for network
        -May not scale to large systems elegantly
-Dynamically configured by inter-switch protocol
        -Requires protocol to be defined (added complexity)
        -Provides good scaleability and availability features




 recode DA information for tagging
 informaiton agreed upon by egress switches...
 LAA addresses: vLAN oui - instance ID - VLAN ID = 48 bit MAC
 only need to do this on multicast addresses...