Figure 2-3 Vpls Working Principle - Zte ZXR10 5900E series Configuration Manual

ZXR10 5900E Series Configuration Guide (VPN)

Figure 2-3 VPLS Working Principle

VPLS working flow is described below.
VPLS establishes full connection of PW among the VPLS instances of PE1, PE2 and PE3.
All the VPLS instances belonging to a VPLS domain use the same VCID.
Here, PE1 allocates VC tags 102 and 103 to PE2 and PE3 respectively. PE2 allocates VC
tags 201 203 to PE1 and PE3. PE3 allocates VC tags 301 and 302 to PE1 and PE2.
Supposing that a host connecting to CE1 sends a MAC frame containing source address
X and destination address Y through PE1. If PE1 does not know the destination PE, it
encapsulates a tag 201 to the MAC frame and then sends the MAC frame to PE2, and it
encapsulates a tag 301 to the MAC frame and then sends the MAC frame to PE3.
After PE2 receiving the MAC frame, it judges that the host connecting to PE1 according to
the tag 201, thus it can learn the MAC address X and bind the X to tag 102 (allocated by
PE1).
There are two modes for PW emulating Ethernet, Raw and Tagged modes.
l
In Raw mode, the type of PW is Ethernet. The packets are transmitted in PW without
PTAG. PTAG will be removed if an AC packet containing PTAG is transmitted in PW.
The information of VLAN tag will not be changed in PW transmission if the AC packet
is transmitted without PTAG.
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In Tag mode, the type of PW is Ethernet-VLAN. The packets are transmitted in PW
with PTAG. PTAG will be kept with the AC packet to transmit to the peer PE if the AC
packet contains PTAG. A PTAG or a special PTAG-Vlan 0tag is encapsulated into the
AC packet if the AC packet is transmitted in PW without PTAG.
Caution!
In both of RAW and Tag modes, the user VLAN tags locating at frame headers are
transmitted transparently without any changing.
SJ-20150114102049-016|2015-03-10 (R1.0)
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