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ETH-QoS Facts


Ethernet standard spans what two layers? Physical Layer & Data Link
What layer/standards apply to the Ethernet standard? Physical & Data Link. IEEE802.3 = Physical & Media Access Controller. IEEE802.2 = Logical Link Controller (Upper Data Link)
How fast is "Fast Ethernet"? What physical Medium? 100Mbps. Typically UTP.
What medium is required for 10 Gigabit Ethernet? Range of Sx versus Lx? Fiber. Sx Range = 200m. Lx range = 5km
Ethernet Naming Convention. What is Baseband versus Broadband? Speed_Tx Technique_Physical Medium Baseband = One signal sent at a time Broadband = Multiple signals simultaneously
Length of MAC Address? Number of possible addresses? How is address split up? EUI 48 = 48 bits in length --> 2^48 Possible Addresses. NOTE: Read right to Left in Hex First 24 bits = Company ID Second 24 bits = Extension Identifier
Describe structure of Ethernet Frame 1)Preamble/SFD (8bits) 2)Dest MAC Address (6 bytes) 3)Source MAC Address (6 bytes) 4)Type (2 bytes) [0800 HEX = IP packet] 5)Data 6)Frame Check Sequence (FCS)(4 bytes)
How do switches vs bridges accomplish switching differently? Bridge = Software Switching Switch = Hardware Switching
What are the advantages of one host collision domains? No collisions & Full Duplex Operation!
What is the broadcast address used by switches? All Hex F's = FF.FF.FF.FF.FF.FF
What are the ports involved in STP? And what are the port states? What are the messages sent? Ports = Root Port, Designated Port, Blocking Port Port States = Blocking, Listening, Learning, Fowarding Messages = BPDUs
RSTP reduces convergence for what types of links? Reduced for: Point to Point & Edge Type Links. NOT reduced for Link Type Shared (Hub)
What are the ports involved in RSTP? Port States? Ports = Designated, Root, Backup (for Des), Alternative (for Root), Disabled Port States = Discarding, Learning, Forwarding
What is a Trunk link? Works using ___ ____? What is an Access port? Link between switches that can carry traffic for any VLAN! _VLAN _Tags! Access port connects to end users. Carries traffic for one VLAN.
What is the standard for VLAN tagging? IEEE802.1Q
What is in an 802.1Q tag? 1) Tag Protocol ID 2) Tag Control Info a] VID = VLAN Identifier b] PCP = Priority Code Point c] CFI = Canonical Format Identifier (1 bit)
Advantages of Link Aggregation (two)? Increased Link Speed. Increased Redundancy.
LACP can use a max of _____ ports and only ____ can be active at any one time. Link Aggregation Requirements? 16 ports, 8 active Requirements = All links full duplex, point to point, same speed
What VLANs are used in Ethernet Ring Protection? --1 Control VLAN (Spans whole ring and can enter Secondary port) --Multiple Data VLANs
ERP response to "Link Down"? Open Secondary Ports & send "Flush Forwarding Database Message" on Control VLAN
ERP response to "Switch Down"? Unblock Secondary Ports
Total VLANs available using 802.1Q? 4096 (VLAN tag = 12 bits in length)
QinQ Scalability Formula (#Services)*(#Sites per Service)*(#Hosts per Site)
What standard governs MAC-IN-MAC Provider Backbone Bridging? IEEE802.1AH
What 3 components make up the Service Provider MAC header? 1)Backbone Destination 2)Backbone Source 3)Backbone TAG
What standard governs Connection Oriented Traffic Engineering? 802.1QAY
What are the 4 requirements on a network? Throughput, Delay, Jitter, Loss
Name the IP Precedence classes. How many bits in IP Precedence? 3 bits = 8 classes 0) Routine 1) Priority 2) Immediate 3) Flash 4) Flash Override 5) Critical 6) Internetwork Control** 7) Network Control** **Reserved for router messages (ICMP, etc)
How does DiffServ improve on IP Precedence? 6 bits = 64 classes (>8) --Includes weighting for drop probability
What are Behavior Aggregates (BAs)? Packets in a network traveling in the same direction with the same DSCP marking. They will be mapped to a Per Hop Behavior (PHB).
What is a DS Region? Group of one or more contiguous DS domains (domains can have different PHB policies and mappings). Use TCAs to agree between the edge routers.
Name the 2 types of Traffic Identifiers. 1) BA Identifier - Classifies packets based ONLY on the DSCP value. 2) Multi-Field (MF) Classifier - Examines a combination of header fields.
How is Differv's DSCP compatible with IP precedence? First 3 bits defites the class = same 8 possible classes. Additional 3 bits define drop probabilities (low, medium, high). EF - Expedited Forwarding (1) AF - Assured Forwarding (4) BE/Default - Best Effort (1)
Name the DiffServ Ingress & Egress Functions. Ingress = Classification, Marking, Policing Egress = Queuing, Scheduling, Congestion Avoidance
Formula for rate in Token bucket model? Rate = (Burst in bits)/(Time Committed in seconds)
What kind of Token Buckets can be stacked? Conforming Burst [Green] Committed Burst (almost conform)[Yellow] Excessive Burst [Red]
Once queue depth is achieved (full), what is the probability of drops? How does queue depth affect performance? 1 or 100% tail drop probability Too big = Big Packet Delay Too small = Tail Drops
How does QoS in L2MPLS work? QoS info is stored in the MPLS header using the 3 bit EXP field to correspond with the IP Precedence in the IP Header (3 MSb's of the DSCP field)
How does QoS in L2Ethernet work? 3 MSb's of the DSCP field propagated into the 3 bit PCP field in the Ethernet header. Governed by 802.1p standard.
Created by: glarsen117