IEEE 802.1ad-2005 pdf free download – I E E E Standard for Local and metropolitan area networks Virtual Bridged Local Area Networks Amendment 4: Provider Bridges.
If the VLAN tag is a Service \‘LAN tag, then Table 6-3 and Table 6-4 shall be supported, lithe VLAN tag is a Customer VLAN tag, then the ttPOI) row of each table shall be supported. and the remaining rows may be supported.
NOTE—To avoid potential nsisordertng ol’ packets, all Pm on a LAN should stIed rIte saint tow of Table 6-3 and Table 6-4 lntrroperahility considesattoiss with Bridges supporting only the SP(ID row are ditaissed in (17.
The values in the Priority Code Paint Encoding Table and Priority Code Point Decoding Table may be modified by managentent. as described in Clause 12. If this capability is pros ided. the value of the table entries shall be independently settah4e for each Port. The values shall he constrained as follows:
a) For any two pnority values with the same drop_eligible value, the lower prtortty shall not map to a higher PUP than the higher priority.
b) The lower of any two PUP valises shall not map to a higher pne’rity than the higher PUP.
c) With the exception of vaiues 0 and I. any prionty value combined with drop_eligible True shall not map to a higher PCP than the same priority value combined with drop_eligible False.
dl With the exception of values 0 atd I,any PUP value shall not map to a pt’sonty value comhtned with drop_eligible True tf a lower ft_P maps to the same priority value combined with drop_eligible False.
The values may be further constrained, hut if the tables can be modified, the default values shown in Table 6-3 and Table 6-4, and the altetnatis’e sets of values in Table 6-3 aid Table 6-4 shall he scrtable.
If the VLAN tag is a Service VLAN tag (S-TAG). the drop_eligible parameter may also be encoded in and decoded from the Drop Eligible Indicator ([Wit m the S-TAG Use of the DEl allows the S-TAG to convey eight distinct priorities, each with a drop eligible indication. If this capability is provided, it shall be independently manageable for each Port by means of a Use_DEl parameter. If the Use_DEl is True for the Port. the drop_eligible parameter is encoded in the DEl of transmitted frames, and the drop_eligible parameter shall be True for a received frame if the DEl is set in the S-TAG or the Priority Code Point Decoding Table indicates drop_eligible True for the received PCP value, lithe Use_DEl parameter is False. the DEl shall be transmitted as zero and ignored on receipt The default value of the Use_DEl parameter is False.
6.74 RegeneratIng prIority
Renumber Table 6-3 as Table 6-5. There are no changes to the remainder of 6.7.4 (renumbered from 6.7.3).
Insert nets subclauses 6.9. 6.10. and 6.1! afler 6.8 as follows:
6.9 Support of the 155 for attachment to a Provider Bridged Network
This standard specifies both Customer Bridges (3.5) and Provider Bridges 13.17). Tlse operation of Provider Bridges and Provider Bridged Networks is. by design. largely transparent to Customer Bridges and Customer Bridged Local Area Networks. Figure 15-I illustrates the relationship of the service provided by the MAC Sublayer functionality of Provider Bridges to that used by a Customer Bridge. This subclause enaNes a mechanism for a Customer Bridge attached to a Provider Bridged Network to request priority handling of frames.IEEE 802.1ad pdf download