SMARTLINK
I&II
MDS921AE-10BTS - MDS
VLAN (Virtual Local Area Network)
Virtual LAN (VLAN) is defined as a group of devices on one or more LANs that are configured so
that they can communicate as if they were attached to the same wire, when in fact
on a number of different LAN segments. Because VLAN is based on logical instead of physical
connections, it is extremely flexible.
The IEEE 802.1Q defines the operation of VLAN bridges that permit the definition, operation, and
administration of VLAN topologies within a bridged LAN infrastructure. VLAN architecture benefits
include:
•
Increased performance
•
Improved manageability
•
Network tuning and simplification of software configurations
•
Physical topology independence
•
Increased security options
As DSL (over ATM) links are deployed more and more extensively and popularly, it is rising
progressively to implement VLAN (VLAN
requirement of ISPs.
We discuss the implementation of VLAN
spreads over both the COE and CPE sides, where there is no layer 3 routing involved.
Specification
•
The unit supports up to 8 active VLANs with shared VLAN learning (SVL) bridge out of
4096 possible VLANs specified in IEEE 802.1Q.
•
Each port always belongs to a default VLAN with its port VID (PVID) as an untagged
member. Also, a port can belong to multiple VLANs and be tagged members of these
VLANs.
•
A port must not be a tagged member of its default VLA
•
If a non-tagged or null
PVID of the ingress port.
•
If the packet is tagged with non
•
The look up process starts with VLAN look up to determine w
VID is not valid, the packet will be dropped and its address will not be learned. If the VID is
valid, the VID, destination address, and source address lookups are performed.
•
The VID and destination address lookup determines
packet will be broadcasted to all members of the VLAN, except the ingress port.
•
Frames are sent out tagged or untagged depend on if the egress port is a tagged or
untagged member of the VLAN that frames belong.
•
If VID and source address look up fails, the source address will be learned.
Frame Specification
An untagged frame or a priority
which it belongs. Such frames are classified as belonging to a parti
parameters associated with the receiving port. Also, priority tagged frames, which, by definition,
carry no VLAN identification information, are treated the same as untagged frames.
A VLAN-tagged frame carries an explicit identification
carries a tag header that carries a non
68 octets. Such a frame is classified as belonging to a particular VLAN based on the value of the
S957AE-10BTS User Manual
Page 13 of 113
VLAN (Virtual Local Area Network)
Virtual LAN (VLAN) is defined as a group of devices on one or more LANs that are configured so
that they can communicate as if they were attached to the same wire, when in fact
on a number of different LAN segments. Because VLAN is based on logical instead of physical
connections, it is extremely flexible.
The IEEE 802.1Q defines the operation of VLAN bridges that permit the definition, operation, and
tion of VLAN topologies within a bridged LAN infrastructure. VLAN architecture benefits
Increased performance
Improved manageability
Network tuning and simplification of software configurations
Physical topology independence
options
As DSL (over ATM) links are deployed more and more extensively and popularly, it is rising
progressively to implement VLAN (VLAN-to-PVC) over DSL links and, hence, it is possible to be a
We discuss the implementation of VLAN-to-PVC only for bridge mode operation, i.e., the VLAN
spreads over both the COE and CPE sides, where there is no layer 3 routing involved.
The unit supports up to 8 active VLANs with shared VLAN learning (SVL) bridge out of
VLANs specified in IEEE 802.1Q.
Each port always belongs to a default VLAN with its port VID (PVID) as an untagged
member. Also, a port can belong to multiple VLANs and be tagged members of these
A port must not be a tagged member of its default VLAN.
tagged or null-VID tagged packet is received, it will be assigned with the default
PVID of the ingress port.
If the packet is tagged with non-null VID, the VID in the tag will be used.
The look up process starts with VLAN look up to determine whether the VID is valid. If the
VID is not valid, the packet will be dropped and its address will not be learned. If the VID is
valid, the VID, destination address, and source address lookups are performed.
The VID and destination address lookup determines the forwarding ports. If it fails, the
packet will be broadcasted to all members of the VLAN, except the ingress port.
Frames are sent out tagged or untagged depend on if the egress port is a tagged or
untagged member of the VLAN that frames belong.
D and source address look up fails, the source address will be learned.
An untagged frame or a priority-tagged frame does not carry any identification of the VLAN to
which it belongs. Such frames are classified as belonging to a particular VLAN based on
parameters associated with the receiving port. Also, priority tagged frames, which, by definition,
carry no VLAN identification information, are treated the same as untagged frames.
tagged frame carries an explicit identification of the VLAN to which it belongs; i.e., it
carries a tag header that carries a non-null VID. This results in a minimum tagged frame length of
68 octets. Such a frame is classified as belonging to a particular VLAN based on the value of the
Virtual LAN (VLAN) is defined as a group of devices on one or more LANs that are configured so
that they can communicate as if they were attached to the same wire, when in fact they are located
on a number of different LAN segments. Because VLAN is based on logical instead of physical
The IEEE 802.1Q defines the operation of VLAN bridges that permit the definition, operation, and
tion of VLAN topologies within a bridged LAN infrastructure. VLAN architecture benefits
As DSL (over ATM) links are deployed more and more extensively and popularly, it is rising
PVC) over DSL links and, hence, it is possible to be a
PVC only for bridge mode operation, i.e., the VLAN
spreads over both the COE and CPE sides, where there is no layer 3 routing involved.
The unit supports up to 8 active VLANs with shared VLAN learning (SVL) bridge out of
Each port always belongs to a default VLAN with its port VID (PVID) as an untagged
member. Also, a port can belong to multiple VLANs and be tagged members of these
VID tagged packet is received, it will be assigned with the default
null VID, the VID in the tag will be used.
hether the VID is valid. If the
VID is not valid, the packet will be dropped and its address will not be learned. If the VID is
valid, the VID, destination address, and source address lookups are performed.
the forwarding ports. If it fails, the
packet will be broadcasted to all members of the VLAN, except the ingress port.
Frames are sent out tagged or untagged depend on if the egress port is a tagged or
D and source address look up fails, the source address will be learned.
tagged frame does not carry any identification of the VLAN to
cular VLAN based on
parameters associated with the receiving port. Also, priority tagged frames, which, by definition,
carry no VLAN identification information, are treated the same as untagged frames.
of the VLAN to which it belongs; i.e., it
null VID. This results in a minimum tagged frame length of
68 octets. Such a frame is classified as belonging to a particular VLAN based on the value of the
