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An innovative low-cost Classification Scheme for combined multi-Gigabit IP and Ethernet Networks. Authors : Ioannis Papaefstathiou , and Vassilis Papaefstathiou . Publisher : IEEE ICC 2006 Present : Yu-Tso Chen Date : October, 15, 2008.
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An innovative low-cost Classification Scheme for combined multi-Gigabit IP and Ethernet Networks Authors:Ioannis Papaefstathiou, and Vassilis Papaefstathiou . Publisher:IEEE ICC 2006 Present:Yu-Tso Chen Date:October, 15, 2008 Department of Computer Science and Information Engineering National Cheng Kung University, Taiwan R.O.C.
Outline • 1. Introduction • 2. DLCE • 3. • 4. Performance Analysis
Introduction • Double Layer Classification Engine (DLCE) • Uses a new hashing scheme and internal replacement of MAC Vendor IDs at the Ethernet layer • Same hashing scheme together with an innovative trie-based engine for the IP classificaton
Double Layer Classification Engine • Every rule in the ruleset is associated to a number called FlowID • 15-bit FlowIDs, translating to 32K unique and independent network flows
Original MAC Address Hashing • Hval = MAC[31:0] • MAC_TBL – Hold the FlowID of the associated rule. MAC_TBLindex
MAC Vendor Replacement • 24-bit vendor address space of the MAC addresses • Fewer than 8000 vendors are active instead of the 224 possible • Each MAC-address rule handled by our system is 37-bits(13+24bit) long • address space can be handled by a 24-to-13 decoder
IP Layer Classification • Uses strides and multi-bit trie nodes in order to traverse several bits at a time and produce fast lookups. • Its nodes are represented with bitmaps that can be processed fast in hardware and require small storage.
Bitmaps • PrefixNO = PrefixValue + 2PrefixLength – 1 • TrieBMP – Efficiently the information about the subtries • PrefixBMP – The information about the active prefixes belonging to subtrie
Bit position of the actual prefix in a specific subtrie PrefixValue 2PrefixLength – 1
Inside the two subtries the candidate prefixes are four Priority High
DLCE Table • The interval 0-7 we have a single entry for root called TBL0 • Interval 8-15 we have 28 possible roots (TBL8) • Interval 16-23 we use a 216=65536 table called TBL16
DLCE Table (cont.) • Interval 24-31 use 216 entries in table TBL24 (indexing by hashing the first 24-bits) • 32 bit prefixes we use only 212 entries in table TBL32
Sequence of lookups • TBL16 → TBL24 → TBL32 → TBL8 → TBL0 • If after TBL32 a match was produced then our lookup process does not proceed to the next tables.
MAC Address Hashing • MAC_TBL – Hold the FlowID of the associated rule. • EXACT_TBL – The number of entries in each variable size block. (Defined by the number of rules that collide within a specific entry)