Ethernet in Carrier Networks Ethernet Reminder Shared access

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Ethernet in Carrier Networks

Ethernet in Carrier Networks

Ethernet Reminder • Shared access medium widespread in LAN environments – CSMA/CD – Frames

Ethernet Reminder • Shared access medium widespread in LAN environments – CSMA/CD – Frames 6 6 2 46 to 1500* 4 Dest. MAC Source MAC Type Payload FCS

Ethernet Flat Address Space

Ethernet Flat Address Space

Ethernet • Ethernet parts are cheap • Ethernet is fairly simple – but can

Ethernet • Ethernet parts are cheap • Ethernet is fairly simple – but can be extended • Ethernet is ubiquitous • Ethernet can carry many different Layer-3 protocols

Ethernet in Carrier Networks • • • PHY types OAM Link Aggregation VLANs Quality

Ethernet in Carrier Networks • • • PHY types OAM Link Aggregation VLANs Quality of Service

Ethernet PHY • Ethernet Physical Layer (PHY) • Layer 1 in OSI model

Ethernet PHY • Ethernet Physical Layer (PHY) • Layer 1 in OSI model

Ethernet PHY • Wide and varied PHY standards – Common Ethernet frame format –

Ethernet PHY • Wide and varied PHY standards – Common Ethernet frame format – Coax / Category 5 Twisted Pair / Wireless / Fiber Optic • Fiber Optics == Lasers – CSMA/CD, CSMA/CA – Coding method: Manchester, 4 B/5 B, 8 B/10 B, 64 B/66 B – Full duplex vs. half duplex – etc

Ethernet PHY • Relatively short distances – 100 base. T – up to 100

Ethernet PHY • Relatively short distances – 100 base. T – up to 100 m – 100 base. FX – up to 4 km full duplex – Gig. E over Fiber – up to 100 km – 10 Gig. E over Fiber – up to 40 km

10 Gig. E PHY • 10 GBASE-SW, EW, LW define Ethernet over SDH STS-192

10 Gig. E PHY • 10 GBASE-SW, EW, LW define Ethernet over SDH STS-192 c networks – S = 850 nm, L = 1310 nm, E = 1550 nm – W == WAN Interface Sublayer – useful for carriers which already have these links in place – reuse existing technology == cheaper.

OAM • Operation, Administration, and Maintenance • Detect network defects – Anomaly • smallest

OAM • Operation, Administration, and Maintenance • Detect network defects – Anomaly • smallest detectable discrepancy between observed and expected behaviour – Defect • function is impaired by density of anomalies – Single Fault • many different correlated defects caused by fault – Failure • fault persists for long enough that network function terminates – Alarm • indication to human of failure Source: Ethernet OAM Whitepaper, RAD Data Communications

Ethernet OAM • 802. 3 ah: “Ethernet in the First Mile” – Ethernet link-layer

Ethernet OAM • 802. 3 ah: “Ethernet in the First Mile” – Ethernet link-layer OAM • 802. 1 ag: “Connectivity Fault Management” – Ethernet Service OAM

Ethernet OAM • Continuity Check (CC) – Special frame sent at regular intervals –

Ethernet OAM • Continuity Check (CC) – Special frame sent at regular intervals – Absence of CC message in 3. 5 x configured interval indicates failure earlier in the link CC alarm Detects fault

Ethernet OAM • Link Trace (LT) message for identifying intermediate points • Loopback (LB)

Ethernet OAM • Link Trace (LT) message for identifying intermediate points • Loopback (LB) message for diagnosing faults – In-service (non-intrusive echo) – Out-of-service (intrusive loopback) – Send LB to first intermediate, then second, until LB is not returned

802. 3 ad link aggregation • aggregate multiple physical ports into single logical link

802. 3 ad link aggregation • aggregate multiple physical ports into single logical link – increase capacity – fault tolerance

802. 3 ad link aggregation Switch PC Switch • Does not reorder packets in

802. 3 ad link aggregation Switch PC Switch • Does not reorder packets in a given conversation • Does not change Ethernet frame format • Does not necessarily provide N times more capacity unless Ethernet-layer traffic is diverse

802. 3 ad link aggregation • requires protocol support from switch – switch sees

802. 3 ad link aggregation • requires protocol support from switch – switch sees same MAC address arrive on multiple ports – otherwise would get quickly confused • Link Aggregation Control Protocol (LACP) – Uses Ether. Type 0 x 8809 • Aggregator advises switch which ports it is aggregating

802. 1 Q Virtual LANs (VLANs) • Allow multiple networks to share same physical

802. 1 Q Virtual LANs (VLANs) • Allow multiple networks to share same physical Ethernet link VLAN Switch

802. 1 Q VLANs • Want to do this without introducing security concerns •

802. 1 Q VLANs • Want to do this without introducing security concerns • Ethernet has a flat address space – Want to do this in a scalable way

802. 1 Q VLANs 6 Destination MAC 6 4 Source MAC VLAN • 4

802. 1 Q VLANs 6 Destination MAC 6 4 Source MAC VLAN • 4 byte tag Type TPID 0 x 8100 – Tag Protocol ID 16 bits – User Priority – Canonical Format Indicator – VLAN ID 46 to 1500* 4 Payload FCS UP VID 3 1 12 bits • FCS is recalculated on VLAN tag insertion

802. 1 Q VLANs • Switch is configured to insert specific VLAN ID for

802. 1 Q VLANs • Switch is configured to insert specific VLAN ID for a given port • Ethernet switches route VLAN frames based on VLAN ID • Ethernet switches may prioritise traffic based on the User Priority field – Defined in 802. 1 p

802. 1 p Traffic Class Expediting • 802. 1 p provides recommended actions for

802. 1 p Traffic Class Expediting • 802. 1 p provides recommended actions for 3 User Priority bits in VLAN tag. – – – – 1, BK, Background 0, BE, Best Effort (default) 2, EE, Excellent Effort 3, CA, Critical Applications 4, VI, Video < 100 ms latency + jitter 5, VO, Voice < 10 ms latency + jitter 6, IC, Internetwork Control 7, NC, Network Control • Approximately maps to first DSCP precedence Source: 802. 1 Q-2005. pdf, page 282

Summary • Ethernet is fairly simple, but has many useful standardised extensions

Summary • Ethernet is fairly simple, but has many useful standardised extensions