INR1056-01_ALCplus2e - New Feature Avalable With FWversion 1.0.0_2011

251642368

ALCplus2e – New feature available

with FW version 1.0.0

Document Number

INR1056

Version

1

Edition

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Issued by

RIGAMG

Approved by

BACCAL

Date

14/7/2011

Page

1 of 8

________________________________________________________________________

ALCplus2e

New feature available with FW version 1.0.0

_______________________________________________________________________

251658752



Document Number

INR1056

Version

1

Edition





Issued by

RIGAMG

Approved by

BACCAL

Date

14/7/2011

Page

2 of 8

Introduction

The ALCplus2e IDU supports, in addition to the same features of ALCplus2, some new features that will be described in this

document.

System Configurations

ALCplus2e is available with the following alternative interface configurations:

- 4GE 18E1 2xSTM1 NODAL

- 4GE 34E1 2xSTM1

- 4GE 2xE1

Each one of these versions can come with different HW versions: 1+0, 1+1 HSB or 2x(1+0) with or without XPIC.

The 2x(1+0) is an additional feature that ALCplus2e has respect to ALCplus2. This allows to manage two different network

configurations:

- East-West interconnections. In this configuration the radio is used to manage two different 1+0 radio connections

with a single IDU. All the Ethernet traffic is managed through the embedded L2 Ethernet switch, that routes the

traffic between the two radio ports and the local GE interfaces. The TDM traffic (up to 80 E1 per radio link) is routed

between the radio ports and the local E1/STM-1 tributary interfaces by means of an embedded TDM cross-

connection matrix.

- Two parallel 1+0 radio links between two sites, used typically to double the link capacity. Two typical solutions are

used to deploy such a solution: two carriers transmitted on a DualPol antenna or on a SinglePol antenna by means

of an hybrid. When the two carriers are transmitted on the two polarizations of a DualPol antenna, ALCplus2e can

provide the XPIC feature in order to reuse the same frequency channel. In this case the Ethernet capacity can be

251658752



Document Number

INR1056

Version

1

Edition





Issued by

RIGAMG

Approved by

BACCAL

Date

14/7/2011

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aggregated in order to double the capacity of the Ethernet connection by means of L1 Ethernet Radio Link

Aggregation (further explained in this document). The E1 traffic to be carried on the radio connection can be either

split or protected between the two 1+0 radios (further explained in this document).

The XPIC feature can work with ACM enabled and is active with all the modulations. It is in addition available for all the

channel bandwidths with the only exception of 7MHz.

40 MHz Channel Bandwidth

ALCplus2e supports 40 MHz channel bandwidth, in addition to the 7, 14, 28 and 56 MHz already provided by ALCplus2. The

40MHz is available in the 6U GHz and 11 GHz frequency bands, where the international standards (CEPT and ITU) and most

of the National Regulators already foreseen a 40MHz carrier raster. In this frequency band the availability of the 40MHz

Channel Bandwidths allows to exploit in a more efficient way the available spectrum. In the following table it is shown the

net radio throughput for the different Channel Bandwidths (expressed in Mbit/s).

4QAMs 4QAM 8PSK 16QAM 32QAM 64QAM 128QAM 256QAM

Channel Bandwidth 7 MHz 8.376 10.440 14.661 21.044 24.966 31.428 35.386 41.708 Channel Bandwidth 14 MHz 17.251 20.782 29.105 41.532 51.866 62.171 72.396 85.138 Channel Bandwidth 28 MHz 35.294 41.609 62.080 82.661 103.629 124.267 144.606 169.950 Channel Bandwidth 40 MHz 49.759 59.979 86.832 117.831 141.206 174.283 205.566 239.163 Channel Bandwidth 56 MHz 71.099 82.752 123.960 165.168 201.639 240.040 286.376 341.131

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Document Number

INR1056

Version

1

Edition





Issued by

RIGAMG

Approved by

BACCAL

Date

14/7/2011

Page

4 of 8

Ethernet Layer 1 Radio Link Aggregation

In the 2x(1+0) configuration ALCplus2e is able to manage two 1+0 radio links with a single IDU. In case the two links are

parallel (i.e. deployed between the same two sites) the Ethernet capacity can be aggregated in order to double the capacity

of the Ethernet connection.

In this case the Link Aggregation mechanism is not based on MAC hashing, but on a more efficient Layer 1 distribution of the

traffic over the two radio channels. The traffic received from the line interfaces, after the L2 Ethernet switch processing, is

fragmented and labelled with proprietary protocols. The additional labelling is used to take trace of the original order of the

fragments before to send it over the radio air. On the receiver side the fragments are recomposed with the original order. In

this way the correct packet order is preserved, despite the frequency channel over which has been sent each packet. The

fragments are then sent over the air in order to balance the load between the two frequency channels. The balancing

mechanisms is able to take into account also for unbalancing in the capacity available over the two radio links (for example,

in the case an ACM modulation down-switch will occur only on one radio branch). The final result is that the traffic is

balanced over the two radio channels on the basis of the available capacity and independently from any other packet

characteristics (source or destination MAC address ecc...). Resiliency between the radio links aggregated is inherently

provided by the balancing mechanisms (if one radio channel becomes unavailable all the traffic will be sent on the other

channel).

The maximum capacity that can be aggregated is relevant to 2x56MHz radio channels, i.e. 2x340Mbit/s. However, due to the

additional fragment labelling used by the protocol there is a slight loss in terms of available capacity over the radio link due

to the additional overhead. This loss is dependent from the Ethernet packet length and is between about 1% (for 1518 bytes

packets) and about 7% (for 64bytes packets).

Selective E1 Protection

This feature is available when 2x(1+0) configuration is used to interconnect two network sites and allows to provide path

protection to the E1 traffic. It is realized by sending the same E1 on the two radio directions and into the selection on the RX

side of the best one based on the quality of the E1 circuit itself. To do this, the E1 circuits are monitored in RX side by looking

at AIS, BER, OOF and OOMF alarms. The E1s can be protected independently from their frame structure (G.704 framed or

not).

For each E1 carried over the radio connection it can be selected if either activate or not the protection: in general, it is

possible to provide protection to all the 82 E1s that can be carried over each single 1+0 radio link.

Enhanced QoS Management

The ALCplus2e scheduler provides enhanced QoS management features. Based on the ingress port (and optionally also as a

function of the VLAN-ID), there are four different modes that can be used to set the priority of an Ethernet frame:

- Ethernet: the priority is set based on the PCP field of the VLAN tag (IEEE802.1p)

- MPLS: the priority is set based on the EXP field of the MPLS tag

- IP: the priority is set based on the DSCP field of the either IPv4 or IPv6

251658752



Document Number

INR1056

Version

1

Edition





Issued by

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Date

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- Default: the priority is set in a static mode and its value is configurable based on the VLAN ID. The Default mode is

also used when all the other criteria are not applicable.

It is in addition possible to map the EXP quality of the MPLS label into the PCP field of the outer VLAN tag.

Once the priority is assigned, the packet is sent to one of the 8 output queues. The size of each one of the 8 queues is

configurable with one value between the following four options: 128 Kbit, 256 Kbit, 512 Kbit and 1024 Kbit.

On the basis of the filling status of the queue, different drop-policy can be applied. In ALCplus2e there are four policies

available:

- Tail drop: if the packet is arriving into a full queue, it will be discarded

- Queue drop: if a new packet is arriving into a full queue, the whole queue is emptied (with the exception of the

head packet)

- RED: when a new packet is arriving into the queue it has a discarding-probability that is function of the filling status

of the queue. The relation between the probability and the queue status is defined by means of a SW configurable

curve. If the queue is full, the new packet is discarder with probability 1 (like in the Tail drop case).

- WRED: it is similar to RED, with the difference that for each queue two drop’s curves are defined. The packet in

ingress is coloured according to MEF 10.2, i.e. according to the CIR and EIR ingress filtering policy defined. As a

consequence, WRED can be chosen only if CIR/EIR Ingress filtering policy is enabled for the ingress port. Once

coloured, “red” packets are always discarded, while “green” and “yellow” packets are managed according two

different curves.

The traffic in the queues is then emptied by means of either Strict Priority or Weighted Fair Queue algorithms. With the Strict

Priority the highest priority takes always precedence. With WFQ the available bandwidth is shared between the different

priorities with configurable weights. It is in addition possible to configure at the same time some queues as Strict Priority and

the remaining as WFQ.

Enhanced VLAN Management

ALCplus2e provides the following enhanced VLAN management features:

- VLAN rewriting

- Selective QinQ based on VLAN and IEEE 802.1p priority

VLAN rewriting

VLAN rewriting is a feature available on radio side that allows to rewrite the VID of C-TAG of the packets received (uplink

side) or sent (downlink side) by the switch.

On uplink side (packets received by the switch) the VID can be rewritten on the basis of the following criteria:

- LAN port + C-VID: new values of C-VID to be written into the packet can be configured on the basis of its original C-

VID and the LAN port where it has been received.

251658752



Document Number

INR1056

Version

1

Edition





Issued by

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Approved by

BACCAL

Date

14/7/2011

Page

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- LAN port + C-VID + priority: new values of C-VID to be written into the packet can be configured on the basis of its

original C-VID + priority and the LAN port where it has been received.

On uplink side it is possible to configure for all the LAN ports up to 64 LAN port + C-VID or LAN port + C-VID + priority criteria.

On downlink side (packets sent by the switch) the VID can be rewritten on the basis of the C-VID of the received packet. I.e.,

new values of C-VID to be written into the packet can be configured on the basis of its original C-VID. It is possible to

configure up to 64 C-VID criteria in downlink, independently by the uplink configuration.

Selective QinQ based on VLAN and IEEE 802.1p priority

VLAN staking (also named QinQ) is a feature that allows an Ethernet frame to include more than one IEEE 802.1Q TAG. The

scope of VLAN staking is to differentiate the traffic at different levels when the packets must cross networks managed by

different entities.

The ALCplus2e radio supports the VLAN staking. Once a packet enters into the radio it is possible to add a new IEEE 802.1Q

TAG with. The VID of the new TAG can be set based on different criteria:

- Ingres port of the packet

- C-VID and priority of the packet when received on the ingress port

The new TAG is added to the packet as a S-TAG. The Ethertype field of the TAG can be set either to standard values (0x88A8,

0x9100, 0x9200, 0x9300) or to any other custom values.

Ingress Filter Policing (CIR/EIR according to MEF 10.2)

ALCplus2e allows to limit the ingress traffic rate on the basis of:

- LAN port (Bandwidth profile per UNI): a different profile is defined for each LAN port (VLAN ID and priority are not

considered in this case by the rate limiting algorithm)

- VLAN (Bandwidth Profile per EVC): a different profile is defined for different VLANs (priority is not considered in this

case by the rate limiting algorithm). Up to 64 VLAN can be managed with different profiles.

- VLAN + priority (Bandwidth Profile per CoS): a different profile is defined for different couples VLAN+priorities (up to

64 different cases can be managed). In this case the packet priority is always considered by the rate limiting

algorithm. More than one priority can be included in the same bandwidth profile.

In general different criteria can be defined for each port/VLAN/priority. Up to 64 Ingress Filtering Policy resources can be

defined and each bandwidth profile defined on the basis either of LAN port, VLAN or VLAN+priority consumes 1 of such

resources.

In order to define the bandwidth profile, the following parameters must be configured:

- CIR (Committed Information Rate): it is the admitted ingress rate (“green” coloured), with values between 0 Kbit/s

and 1 Gbit/s.

251658752



Document Number

INR1056

Version

1

Edition





Issued by

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Approved by

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Date

14/7/2011

Page

7 of 8

- CBS (Committed Burst Rate): it is the maximum size of the token bucket of the green packets, with values between

0 byte and 256 Kbyte.

- EIR (Excess Information Rate): it is maximum ingress rate eventually admitted (“yellow” coloured), with values

between 0Kbit/s and 1Gbit/s.

- EBS (Excess Burst Rate): it is the maximum size of the token bucket of the yellow packets, with values between 0

byte and 256 Kbyte.

- CF (Coupling Flag): if enabled, the excess token eventually charged into the green bucket are moved into the yellow

packet bucket.

Red packets, i.e. the ones exceeding the CIR+EIR rate, are automatically discarded.

Ethernet frame fragmentation

QoS preserve High priority traffic, by giving them precedence during traffic congestions. However, in case of real time traffic

also latency and jitter are important factors. Latency is strictly relate to the line speed and usually can be managed by

designing the network topology in a proper way (e.g. by limiting the maximum number of hops in link chains). Jitter is instead

a more sensitive parameter because it depends on the traffic conditions.

In fact, when a High priority packet has to be sent over the radio link it is scheduled on a High Priority queue. However,

before to be sent over the radio link it has to wait that the packet currently in transmission (also a Best Effort packet) will be

entirely sent. This waiting time can considerably change depending on the best effort packet size (from 64bytes to 1518

bytes of even more in case of jumbo frames). One technique used to mitigate this phenomenon is packet fragmentation, i.e.

longer frames are subdivided in smaller fragments at TX side. A label is added to the packet in order to number these sub-

frames. At RX side the original frame is rebuilt after all the fragments are received. In this way, the maximum waiting time for

a High Priority packet is reduced to the sub-frame size (some hundreds of bytes), providing sensitive benefits to the packet

jitter.

ALCplus2e allows to fragment Ethernet frames with two options : 256 or 512 Bytes.

Packet Compression

ALCplus2e provided header packet compression. This feature allows to compress the packet header by transmitting over the

radio link proprietary labels in place of long and repetitive header field.

ALCplus2e Single Layer Packet Compression supports the following protocols: Ethernet, MPLS, IPv4/IPv6, UDP and RTP and

LTE S1 interface tunnelling. This latter cover the case of LTE eNodeB backhauling on S1 interface, where the eUE traffic

(either IPv4 or IPv6) is enveloped into a GTP-U tunnel. The header compressed in this case includes (IPv4+UDP+GTP-U of the

S1 interface)+(IPv4/IPv6+UDP+RTP of the eUE traffic inserted into the tunnel).

When enabled, the user can select which header have to be compressed considering the following maximum limits:

- The total header field size cannot exceed 124 bytes

- The total header field size after internal coding cannot exceed 118 bytes. The internal coding is required by

ALCplus2e in order to perform the compression task.

251658752



Document Number

INR1056

Version

1

Edition





Issued by

RIGAMG

Approved by

BACCAL

Date

14/7/2011

Page

8 of 8

In the following table are detailed the different header fields that can be selected with their weight in terms of header field

size and header field size after internal coding.

Header

field size

[Bytes]

Header field

size after

internal

coding [Bytes]

� Ethernet +14 +12.5

� C-TAG (802.1Q) +4 +2

� Q-in-Q (802.1ad) - -

Max number of S-TAG (from 1 to 2) … (default = 1) +(4*n) +(2*n)

� MAC-in-MAC (802.1ah) +22 +18

� MPLS - -

Max number of MPLS labels (from 1 to 3), PW included … (default = 2) +(4*n) +(4*n)

� Control Word (RFC4385) +4 +3.5

� IP+ - -

� IPv4 only (default) +20 +19.5

� IPv4 o IPv6 +40 +39.5

� UDP +8 +8

� RTP

+12 +12

� Tunneling IPv4 – IPv4/IPv6 (IPv4 + UDP + GTP-U + IPv4/IPv6 + UDP + RTP) +100 +99

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INR1056-01_ALCplus2e - New Feature Avalable With FWversion 1.0.0_2011