Figure3: A Metro Ethernet Network with MX Series Routers
InFigure 3 on page 16, the circled numbersreflect the different formats that the Ethernet
framescan take as the frames make their wayfrom a host on one Ethernet switching
hubto a host on the other hub. The frame can have twoVLAN tags (inner and outer),
onetag (only the inner), or no tags at all. The structureof these various Ethernet frames
isshown in Figure 4 on page 16.
Figure4: VLAN Tags on a Metro Ethernet Network
Asthe frame flowsfrom a LAN-based host on one end of Figure 4 on page 16 to the other,
theEthernet frame can have:
NoVLAN tags—At locations 1 and 5, the Ethernet framescan be native and have no
VLANtags at all (many NIC cards can include configurationof a VLAN identifier, but
notall).
OneVLAN tag—At locations 2 and 4,from the VLAN-aware switching hub to the MX
Seriesrouter, the Ethernet frame hasone VLAN tag (if a VLAN tag is not present on
arrivingframes, a tag is added by the MX Series router).
TwoVLAN tags—Atlocation 3, between two provider bridges, the MX Seriesrouters
exchangeframes with two VLAN tags. Theouter tags are added and removed by the
MXSeries routers.
Related
Documentation
MXSeries Ethernet Services Routers SolutionsPage
EthernetTerms and Acronymson page 3
Copyright© 2010, Juniper Networks,Inc.16
Junos10.4 MX Series Ethernet ServicesRouters Solutions Guide