-
Confidential Information of Huawei. No Spreading Without
Permission
Content
I P
Overview...................................................................................................Pa
g e 4
M P L S T u n n e l
Technology
............................................................................Page16
M P L S - T P
Technology ...Page36
Q i n Q
Overview ....Page43
P W E 3
Overview ...Page46
P-0 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Understanding the IP address knowledge are the basics for the
further IP address
configuration or planning in OptiX OSN 1500/3500/7500/7500II
Hybrid MSTP
products.
MPLS basics and MPLS LSP are the emphasis of the course, it is
the generic basics
of OptiX OSN 1500/3500/7500/7500II Hybrid MSTP products
application and
configuration.
Understanding the PWE3 position in the OptiX Hybrid MSTP network
and its
basic concepts.
P-1 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-2 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-3 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
The physical layer contains the protocols relating to the
physical medium on which TCP/IP will be communicating.
Electrical/optical protocols describe signal characteristics
such as voltage or photonic levels, bit timing, encoding, and
signal shape.
Mechanical protocols are specifications such as the dimensions
of a connector or the metallic makeup of a wire.
Functional protocols describe what something does.
Procedural protocols describe how something is done. For
example, a binary 1 is represented on an EIA-232-D lead as a
voltage more negative than 3 volts.
The data link layer contains the protocols that control the
physical layer: how the medium is accessed and shared, how devices
on the medium are identified, and how data is framed before being
transmitted on the medium. Examples of data link protocols are IEEE
802.3/Ethernet, IEEE 802.5/Token Ring, and FDDI.
The network layer, corresponding to the OSI network layer, is
primarily responsible for enabling the routing of data across
logical internetwork paths, by defining a packet format and an
addressing format.
The transport layer, corresponding to the OSI transport layer,
specifies the protocols that control the network layer, much as the
data link layer controls the physical layer. Both the transport and
data link layers can define such mechanisms as flow and error
control. The difference is that while data link protocols control
traffic on the data link, the physical medium connecting two
devices, the transport layer controls traffic on the logical link,
the end-to-end connection of two devices whose logical connection
traverses a series of data links.
The application layer corresponds to the OSI session,
presentation, and application layers. The most common services of
the application layer provide the interfaces by which user
applications access the network.
P-4 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
The physical layer contains the protocols relating to the
physical medium on
which TCP/IP will be communicating.
The data link layer contains the protocols that control the
physical layer: how the
medium is accessed and shared, how devices on the medium are
identified, and
how data is framed before being transmitted on the medium.
Examples of data
link protocols are IEEE 802.3/Ethernet, PPP, HDLC, FR etc.
The network layer is primarily responsible for enabling the
routing of data across
logical internet paths, by defining a packet format and an
addressing format.
Examples of network layer protocols are IP, ICMP, ARP etc.
The transport layer controls traffic on the logical link, the
end-to-end connection
of two devices whose logical connection traverses a series of
data links. Examples
of transport layer protocols are TCP/UDP.
The most common services of the application layer provide the
interfaces by
which user applications access the network. Examples of
transport layer
protocols are HTTP, Telnet, FTP, Ping etc.
P-5 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Version: Identifies the I P version to which the packet belongs.
This four-bit field
is usually set to binary 0100; version 4 (IPv4) is in current,
common use. A newer
version of the protocol, is version 6 (IPv6).
Header Length: tells the length of the IP header.
Type of Service (TOS): generally used for Qos. This field
actually can be broken
down into two subfields: Precedence and TOS.
Total Length: specifying the total length of the packet,
including the header, in
octets.
Identifier/ Flags/ Fragment Offset: these three fields are used
for fragmentation of
a packet.
Time to Live (TTL): is set with a certain number when the packet
is first generated.
As the packet is passed from router to router, each router will
decrement this
number.
Protocol: gives the "address," or protocol number, of the
host-to-host or transport
layer protocol for which the information in the packet is
destined.
Header Checksum: is the error correction field for the
IP-header.
Source and Destination Addresses: are the originator of the
packet and the
destination of the packet.
Options: is a variable-length field, and is optional.
Padding: ensures that the header ends on a 32-bit boundary by
adding zeros after
the option field until a multiple of 32 is reached.
P-6 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
IP addresses are 32 bits long; like all network-level addresses,
they have a
network portion and a host portion. The network portion uniquely
identifies the
network and is common to all devices attached to the network.
The host portion
uniquely identifies a particular device attached to the
network.
The hierarchical design of IP address reduces the size of route
entry and it is very
flexible.
The binary to decimal calculation is as the example,
the binary 11101001 is represented by decimal format:
1*128+1*64+1*32+0*16+1*8+0*4+0*1+1*1=233.
P-7 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-8 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Class A IP addresses are for big internetworks. The first octet
is the network
portion, and the last three octets are the host portion. Only
256 numbers are
available in the eight-bit network part, but 224 or 16,777,216
numbers are
available in the host part of each of those network
addresses.
Class B addresses are for medium-size internetworks. The first
two octets are the
network portion , and the last two octets are the host portion.
There are 216 or
65,536 available numbers in the network part and an equal number
in the host
part.
Class C addresses are just the opposite of class A. The first
three octets are the
network portion, and the last octet is the host.
Class D addresses are reserved for multicast. Class E addresses
are reserved for
future use.
The most commonly used addresses are from A, B and C. The IP
addresses are
allocated by International Network Information Center.
P-9 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Private IP addresses are usually used by enterprise internal
network.
Inter-NIC reserved the following IP addresses for private
use:
Class A: 10.0.0.0~10.255.255.255
Class B: 172.16.0.0~ 172.31.255.255
Class C: 192.168.0.0~192.168.255.255
Private IP addresses can not be used to access Internet, because
public network
has no routes for private IP addresses. NAT (Network Address
Translation) can be
used to translate private addresses into public addresses
P-10 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
The address for an entire data link, a non-host-specific network
address is
represented by the network portion of an IP address, with all
host bits set to zero.
Each device or interface will be assigned a unique,
host-specific address such as
192.168.1.1. The device obviously needs to know its own address,
but it also
needs to be able to determine the network to which it belongs,
in this case,
192.168.1.0.
This task is accomplished by means of an address mask. The
address mask is a 32-
bit string, one bit for each bit of the IP address. As a 32-bit
string, the mask can
be represented in dotted-decimal format just like an IP
address.
P-11 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
A single class A, B, or C address can be used only on a single
data link. To build an
internetwork, separate addresses must be used for each data link
so that those
networks are uniquely identifiable. If a separate class A, B, or
C address were
assigned to each data link, less than 17 million data links
could be addressed
before all IP addresses were depleted. This approach is
obviously impractical, as
is the fact that to make full use of the host address space in
the previous example,
more than 65,000 devices would have to reside on data link
172.16.0.0.
The only way to make class A, B, or C addresses practical is by
dividing each
major address, such as 172.16.0.0, into sub-network
addresses.
The IP address now has three parts: the network part, the subnet
part, and the
host part. The address mask is now a subnet mask, or a mask that
is longer than
the standard address mask.
For example, the first three octets of the address of
192.168.1.17 will always be
192.168.1, but the fourth octet whose first four bits are now
subnet bits instead
of host bits. The range is 0 to 15. it has 16 subnets and 14
host IP addresses in
each subnet.
P-12 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
For point to point link, two IP addresses is enough, so the mask
length is 30:
255.255.255.252
For broadcast link, the mask length is decided by host number of
broadcast
network: if there are 60 hosts, mask length should be 26. if
there are 120 hosts,
mask length should be 25.
For device identifier, for example, OSPF and BGP Router ID,
loopback address is
used directly. The mast length for loopback address is 32, which
is the same to
MPLS LSR ID.
P-13 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-14 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-15 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-16 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
The Internet based on the IP technology prevails in the middle
1990s. The IP
technology, however, performs poorly in forwarding packets
because of the
inevitable software dependence on searching routes through the
longest match
algorithm. As a result, the forwarding capability of IP
technology becomes a
bottleneck to the network development.
P-17 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
To improve the forwarding capability, the Asynchronous Transfer
Mode (ATM)
technology comes out. It uses labels (namely, cells) of fixed
length and maintains a
label table that is much smaller than a routing table.
Therefore, compared with
the IP technology, the ATM technology performs much better in
forwarding
packets. The ATM technology, however, is difficult to popularize
because of its
complex protocol and high cost in deployment.
P-18 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
The traditional IP technology is simple and costs little in
deployment.
People then are eager to making a technical breakthrough to
combine
advantages of IP and ATM technologies. Thus, the MPLS
technology
comes forth.
Initially, MPLS emerges to increase the forwarding rate of
routers.
Compared with IP routing, when forwarding packets, MPLS analyzes
the
IP packet header only on the network edge but not at each hop.
In this
way, the time to process packets is shortened.
P-19 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
MPLS is the abbreviation of Multi-Protocol Label Switching. MP
means it support
more than one protocol, such as IP, IPv6, IPX, SNA, etc. as we
know, in IP
network, the routers forwarding packets by using packets
destination IP address
and looking for the IP routing table to get the next hop, while
in MPLS network,
we using label to forward the packets, named label switching.
MPLS uses a short
label of fixed length to encapsulate packets. MPLS use FEC
(Forwarding
Equivalent Class) to classify the forwarding packets. The
packets of the same FEC
are treated the same in the MPLS network. later we will
introduce the FEC.
By adding a label to the packet at the entrance of MPLS network,
the packet is
forwarded by label switching, some thing like ATM Switching. And
when leaving
the MPLS network, the label added is removed and the label
packet is restored to
original protocol packet.
For more details about MPLS, refer to RFC 3031 (Multi-protocol
Label Switching
Architecture).
P-20 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
LSR is the basic component of the MPLS network. The network
consisting of LSRs,
is called an MPLS domain. The LSR which located at the edge of
the domain and
having a neighbor which not running MPLS is an edge LSR, also
called Labeled
Edge Router (LER).
The LSR located inside the domain is called a core LSR. The core
LSR can be either
a router that supports MPLS or an ATM-LSR upgraded from an ATM
switch. MPLS
runs between LSRs in the domain, and IP runs between an LER and
an router
outside the domain.
The LSRs along which labeled packets are transmitted form an
LSP.
P-21 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Label Switched Path
The path that IP packets pass through on an MPLS network is
called the
LSP. An LSP is a unidirectional path in the same direction with
the data
flow.
The beginning node of an LSP is called the ingress. The end node
of the
LSP is called the egress. The nodes between both ends along the
LSP are
transits. An LSP may have none, one, or several transit(s), but
only one
ingress and one egress.
Ingress
Indicates the beginning of an LSP. Only one ingress exists on an
LSP.
The ingress pushes a new label to the packet and encapsulates
the IP
packet as an MPLS packet to forward.
Transit
Indicates the middle node of an LSP. Multiple transits may exist
on an LSP.
The transit mainly searches in the label forwarding table. Then,
it swaps
the labels to complete the forwarding of MPLS packets.
Egress
Indicates the end node of an LSP, only one egress exists on an
LSP.
The egress mainly pops labels out of MPLS packets and forwards
the
packets that restore the original encapsulation.
The ingress and egress serve as LSRs and LERs. The transit
serves as the LSR.
P-22 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
A label is a short identifier of fixed length with only local
significance. It is used to
uniquely identify an FEC to which a packet belongs. In some
cases like load
balancing, different labels are assigned to an FEC, but one
label only represents
one FEC on a router. The label is a connection identifier,
similar to the ATM
VPI/VCI and the Frame Relay DLCI.
A label is 4 bytes long. The above figure shows the
encapsulation structure of the
label.
A label contains the following fields:
Label: indicates the value field of a label. The length is 20
bits. Label
space means the range of label values. Generally, the label
space is
classified as follows:
015: indicates special labels.
161023: indicates the label space shared by static LSPs and
CR-
LSPs.
1024 or above: indicates the label space for dynamic
signaling
protocols, such as LDP, RSVP-TE, and MP-BGP.
Exp: indicates the bits used for extension. The length is 3
bits. Generally,
this field is used for the Class of Service (CoS) that serves
similarly to
Ethernet 802.1p.
S: identifies the bottom of a label stack. The length is 1 bit.
MPLS
supports multiple labels, namely, the label nesting. When the S
field is 1,
it means that the label is at the bottom of the label stack.
TTL: indicates Time To Live. The length is 8 bits. This field is
the same to
the TTL in IP packets.
Labels are encapsulated between the data link layer and the
network layer. Thus,
labels can be supported by any protocol of the data link
layer.
P-23 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
A label stack is a set of arranged labels. An MPLS packet
carries multiple
labels at the same time. The label next to the Layer 2 header is
called the
top label or the outer label. The label next to the Layer 3
header is called
the bottom label or inner label. Theoretically, MPLS labels can
be nested
limitlessly.
The label stack organizes labels according to the rule of
Last-in, First-Out
and processes labels from the top of the stack.
P-24 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
The Forwarding Equivalence Class (FEC) is a set of data flows
with the same
attributes. These data flows are processed in the same way by
LSRs during
transmission.
FECs are identified by the address, service type, and QoS. For
example, during IP
forwarding through the longest match algorithm, packets with the
same
destination belong to an FEC.
P-25 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Push
When an IP packet enters an MPLS domain, the ingress adds a new
label to
the packet between the Layer 2 header and the IP header; or, a
transit
adds a new label to the top of the label stack, namely, the
label nesting.
Swap
When a packet is transferred within an MPLS domain, a label is
deleted
from the top of the label stack and a new label of the next hop
is added
according to the label forwarding table.
Pop
When a packet leaves an MPLS domain, the label is popped out of
the
MPLS packet; or, the top label of the label stack is popped out
at the
penultimate hop on an MPLS network to decrease the labels in the
stack.
Penultimate Hop Popping
In fact, the label is useless at the last hop of an MPLS domain.
In this case,
the feature of penultimate hop popping (PHP) is applied. On
the
penultimate node, the label is popped out of the packet to
reduce the size
of the packet that is forwarded to the last hop. Then, the last
hop directly
forwards the IP packet or the VPN packet.
P-26 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
The availability of a static LSP makes sense only for the local
node that cannot
sense the entire LSP.
On the ingress: A static LSP is set up, and the outgoing
interface of the
ingress is enabled with MPLS. If the route is reachable, the
static LSP is Up
regardless of the existence of the transit or egress. A
reachable route
means that a route entry exists whose destination address and
the next
hop address match those in the local routing table.
On the transit: A static LSP is set up, and the incoming and
outgoing
interfaces of the transit are enabled with MPLS. If the incoming
and
outgoing interfaces are Up on the physical layer and protocol
layer, the
static LSP is Up, regardless the existence of the ingress,
egress, or other
transits.
On the egress: A static LSP is configured, the incoming
interface of the
egress is enabled with MPLS. If the incoming interface is Up on
the physical
layer and protocol layer, the static LSP is Up, regardless the
existence of
the ingress or the transit.
A static LSP is set up without label distribution protocols or
exchanging control
packets. Thus, the static LSP costs little and it is applicable
to small-scale
networks with simple and stable topology. The static LSP cannot
vary with the
network topology dynamically. The administrator needs to
configure the static
LSP.
P-27 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Dynamic LSPs are set up automatically by the signaling protocol.
The following
label distribution protocols are applicable to an MPLS
network.
LDP
The Label Distribution Protocol (LDP) is specially defined for
distributing
labels. When LDP sets up an LSP in hop-by-hop mode, LDP
identifies the
next hop along the LSP according to the routing and forwarding
table on
each LSR. Information contained in the routing and forwarding
table is
collected by IGP and BGP. LDP indirectly uses routing
information rather
than is directly associated with the routing protocols.
RSVP-TE
The Resource Reservation Protocol (RSVP) is designed for the
integrated
service module and is used to reserve resources on nodes along a
path.
RSVP works on the transport layer and does transmit application
data.
RSVP is a network control protocol, similar to the Internet
Control Message
Protocol (ICMP).
RSVP is extended to support the setting up of a Constraint-based
Routed
LSP (CR-LSP). The extended RSVP is called the RSVP-TE signaling
protocol.
It is used to set up TE tunnels.
P-28 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
An MPLS tunnel is shown above. The MPLS label 100, 200 and 300
are assigned
by the operator.
P-29 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-30 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
An MPLS label has a TTL field in the length of 8 bits. The TTL
field is the same as
that in an IP packet header. MPLS processes the TTL to prevent
loops and
implement traceroute.
RFC 3443 defines two modes in which MPLS processes the TTL, that
is, uniform
mode and pipe mode. By default, MPLS processes the TTL in Pipe
mode.
Uniform Mode
When IP packets enter an MPLS network, on the ingress, the IP
TTL
decreases by one and is mapped to an MPLS TTL field. Then, the
TTL field
in MPLS packets is processed in the standard mode. As shown in
the figure,
on the egress, the MPLS TTL decreases by one and is mapped to
the IP TTL
field.
P-31 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Pipe Mode
As shown in the figure, on the ingress, the IP TTL decreases by
one and the
MPLS TTL is constant. Then, MPLS TTL is processed in the
standard mode.
On the egress, IP TTL decreases by one. That is, when IP packets
enter an
MPLS network, the IP TTL decreases by one only on the ingress
and egress.
P-32 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
The OptiX Hybrid MSTP products support the MPLS tunnels over the
following
Layer 2 links:
FE
GE
10GE
Note: Currently OptiX Hybrid MSTP products only support static
Tunnel (LSP).
P-33 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-34 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-35 Hybrid MSTP Technology Introduction
-
Penultimate Hop Popping (PHP) is a function performed by certain
routers in
an MPLS enabled network. It refers to the process whereby the
outermost label of
an MPLS tagged packet is removed by a Label Switch Router (LSR)
before the
packet is passed to an adjacent Label Edge Router(LER).
Equal Cost Multi Path (ECMP) is a routing strategy where
next-hop packet
forwarding to a single destination can occur over multiple "best
paths" which tie
for top place in routing metric calculations. It potentially
offers substantial
increases in bandwidth by load-balancing traffic over multiple
paths; however,
there can be significant problems in its deployment in
practice.
Confidential Information of Huawei. No Spreading Without
Permission
P-36 Hybrid MSTP Technology Introduction
-
MPLS-TP started as Transport-MPLS at the ITU-T (see G.81xx
series of ITU-T
Recommendations), which was renamed to MPLS-TP based on the
agreement that
was reached between the ITU-T and the IETF to produce a
converged set of
standards for MPLS-TP.
Transport-MPLS (T-MPLS) was a standardization effort that was
undertaken by
the ITU-T. ITU-T approved the first version of its packet
transport
recommendation called Transport MPLS (T-MPLS) Architecture in
2006. By 2008,
the technology had reached the stage where some vendors started
supporting T-
MPLS in their optical transport products. At the same time, the
IETF was working
on a new mechanism called Pseudo Wire Emulation Edge-to-Edge
(PWE3) that
emulates the essential attributes of a service such as ATM, TDM,
Frame Relay or
Ethernet over a Packet Switched Network (PSN), which can be an
MPLS network
[RFC3916].
A Joint Working Group (JWT) was formed between the IETF and the
ITU-T to
achieve mutual alignment of requirements and protocols. On the
basis of the JWT
activity, it was agreed that future standardization work will
focus on defining
MPLS-Transport Profile (MPLS-TP) within the IETF using the same
functional
requirements that drove the development of T-MPLS.
Confidential Information of Huawei. No Spreading Without
Permission
P-37 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-38 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-39 Hybrid MSTP Technology Introduction
-
For the MPLS-TP, the function of Data Plane as the IP/MPLS can
be static
configured by NMS, including the OAM.
IP/MPLS:
OSPF protocal complete the routing table creation.
LDP (Label Distribution Protocol):is a protocol in which routers
capable
of Multiprotocol Label Switching (MPLS) exchange label
mapping
information. LDP can be used to distribute the inner label
(VC/VPN/service
label) and outer label (path label) in MPLS.
MPLS-TP:
NMS Configuration: The label is generated by the NMS, then
forwarding to
the equipment to create the LFIB (Label Forwarding Information
Base).
Control Plane: GMPLS, Equipment can without the IP protocal.
Confidential Information of Huawei. No Spreading Without
Permission
P-40 Hybrid MSTP Technology Introduction
-
The MPLS-TP control plane is based on a combination of the MPLS
control plane
for PW and the GMPLS control plane for MPLS-TP LSPs,
Confidential Information of Huawei. No Spreading Without
Permission
P-41 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-42 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
QinQ technology is a VLAN stacking technology, which conforms to
the
recommendation for S-VLAN in IEEE 802.1ad and is an expansion of
VLAN
technology.
The default Tag Protocol Identifier (TPID) value is 0x8100. It
can be modified in
OptiX Hybrid MSTP.
Advantages of QinQ technology:
Expands VLAN and alleviates VLAN resource insufficiency. For
example, a
VLAN providing 4096 VLAN IDs can provide 4096 x 4096 VLANs
after
VLAN stacking;
Extends LAN service to WAN, connecting the client network to the
carrier
network and supporting transparent transmission.
The default Tag Protocol Identifier (TPID) value is 0x8100
The TPID can be modified in OptiX PTN product
P-43 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
The feature of this service is that the services are isolated by
using the QinQ
technology. The advantage is that the network-side link is
shared. When the
number of user VLANs is large, and multiple users use the same
VLAN, this
networking type can be used.
In this case, the packets of different companies accessed on the
user side are
added to different S-VLANs, and then are carried by the same
link on the network
side.
P-44 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-45 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-46 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Concept of PW
The Mechanism that bears the simulated layer 2 services between
clients to the packet switch network (PSN).
AC: attachment circuit.
It is the physical or virtual circuit that connects a CE to a
PE.
Forwarder
A PE sub-system that selects a PW to transmit the payload
received on the AC.
PW signaling
The basis on which PWE3 is implemented. It is used for creating
and maintaining PWs. Currently, the primary PW signaling is
LDP.
PW: pseudo wire.
It is a mechanism that carries the essential elements of an
emulated circuit between PEs over a PSN.
CE: Customer Edge.
It is a device that originates or terminates a service. The CE
cannot be aware whether an emulated service or a local service is
in use.
PE: Provider Edge.
It is a device that provides PWE3 to a CE. It is usually the
edge router that is connected to a CE on a backbone network. A PE
is responsible for processing the VPN service. A PE performs the
mapping and forwarding of the packets from the private network to
the public-network tunnels and that in the reverse order.
CW: control word.
A control word is a 4-byte encapsulated packet header. It is
used to transmit packets in an MPLS PSN.
P-47 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-48 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-49 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-50 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Normally, the Ethernet service need not be transmitted according
to strict
sequence. In ITU-T G. 802.3, however, it is required that frames
from the same
session should be transmitted according to the sequence. It
cannot be assumed
that the PSN can realize the frame sorting. If strict sorting is
required, the serial
number need be used.
The following describes the meaning of each field in the CW:
The first four bits must be 0, which indicates that the data is
the PW data.
The packet must be ignored by the PE that receives the
packet.
Reserved: It is of 12 bits. It is the reserved field and is
often set to 0.
Sequence Number: It is of 16 bits. It is used to guarantee the
packet order.
This field is optional. If the Sequence Number is 0, it means
the packet
order check is disabled.
P-51 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-52 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
OptiX Hybrid MSTP equipment support TDM E1 PWE3, also we named
it as CES
(Circuit Emulation Service) E1
Between BTS and BSC, the CES service is transported through the
Hybrid MSTP
equipment.
BTS use E1 connection connected to PE. BSC use one channelized
STM-1
connection connected to PE.
P-53 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Unframed E1
Using all the time slots as a whole to transmit user data.
So, the total bandwidth for one unframed E1 connection is
2.048Mbps,
just like the bandwidth provided by a serial interface.
Framed E1
Time slot 0 used for signaling or other purpose.
Time slot 1-31 can be used for transmit service data for
different users.
For example: Time slot 1 can be used for user1 to provide 64
Kbps
bandwidth, and time slot 11 to 12 can be used for user 2 to
provide 128
Kbps bandwidth.
To use a PW to emulate the transmission of TDM service over a
PSN, the
following elements must be carried to the other end of the
PW.
TDM data
Frame format of TDM data
TDM alarm and signaling at the AC side
Synchronous timing information of TDM
P-54 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
In the SAToP mode:
The equipment regards TDM signals as constant rate bit flows,
instead of
sensing structures in the TDM signals. The entire bandwidth of
TDM
signals is emulated.
The overhead and payload in the TDM signal are transparently
transmitted.
In the CESoPSN mode:
The Hybrid MSTP equipment senses frame structures, frame
alignment
modes and timeslots in the TDM circuit.
The Hybrid MSTP equipment processes the overhead and extracts
the
payload in TDM frames. Then, the equipment delivers the timeslot
of each
channel to the packet payload according to certain sequence. As
a result,
the service in each channel in the packet is fixed and
visible.
P-55 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Tunnel label: MPLS label, manually configured in OptiX Hybrid
MSTP equipment.
PW label: manually configured.
Control Word: must use, to identify the sequences of the
frames.
RTP (Real Time Protocol) Header/ Time Stamp/ SSRC Identifier: if
RTP is required,
these encapsulations are required; if not, not required.
To improve the efficiency of the bandwidth, several E1 frames
can be cascaded as
one unit, it means several E1 frame use one PWE3, Tunnel and
Ethernet
encapsulation. The size of the unit is based on the
configuration of buffering time.
By default the buffering time is 1ms. The larger value of
buffering time the higher
bandwidth efficiency and also larger service delay.
P-56 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
Differences of CESoPSN and SAToP:
The CESoPSN protocol can identify frame structure of TDM
service. It may
not transmit idle timeslot channels, but it only extracts useful
timeslots of
CE devices from the E1 traffic stream and then encapsulates them
into PW
packets for transmission.
For example: only time slot 1-5 have data, all the other time
slots are idle,
CESoPSN can choose only transmit time slot 1-5s data to another
PE, the
opposite PE can reconstruct the original E1 frame, and then send
it to
appropriate CE.
P-57 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-58 Hybrid MSTP Technology Introduction
-
Confidential Information of Huawei. No Spreading Without
Permission
P-59 Hybrid MSTP Technology Introduction