Token Ring Lane On Atm - Cisco Catalyst 5000 Series Manual

Token Ring LANE on ATM

Token Ring LANE on ATM
LANE bridges LAN traffic across an ATM network. The Catalyst 5000 Series Token Ring LANE feature
emulates an IEEE 802.5 Token Ring LAN using ATM technology. LANE is transparent to upperlayer
protocols and applications. No changes are required to existing upperlayer protocols and applications. With
Token Ring LANE, Token Ring packets are encapsulated in the appropriate ATM cells and sent across the
ATM network. When the packets reach the other side of the ATM network, they are deencapsulated.
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Benefits
ATM is a cell-switching and multiplexing technology that combines the benefits of circuit switching
(constant transmission delay and guaranteed capacity) with those of packet switching (flexibility and
efficiency for intermittent traffic). Like X.25 and Frame Relay, ATM defines the interface between the user
equipment (such as workstations and routers) and the network (referred to as the User-Network Interface
[UNI]).
Token Ring LANE allows Token Ring LAN users to take advantage of the benefits of ATM without
modifying end-station hardware or software. ATM uses connection-oriented service with point-to-point
signalling or multicast signalling between source and destination devices. However, Token Ring LANs use
connectionless service. Messages are broadcast to all devices on the network. With Token Ring LANE,
routers and switches emulate the connectionless service of a Token Ring LAN for the end stations.
By using Token Ring LANE, you can scale your networks to larger sizes while preserving your investment
in LAN technology.
Note
The Catalyst 5000 series Cisco IOS Token Ring LANE software does not support Ethernet LANE or RFC
1483 permanent virtual connections (PVCs).
LANE Token Ring Components
LANE defines emulated LANs (ELANs). An ELAN consists of the following components:
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If a switch has LECs for multiple ELANs, the switch can route traffic between ELANs.
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There is one LES per ELAN.
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Benefits, page 2
LANE Token Ring Components, page 2
LANE client (LEC)--A LEC emulates a LAN interface to higher-layer protocols and applications. It
forwards data to other LANE components and performs LANE address resolution functions. Each
LEC is a member of only one ELAN. However, a switch or a Catalyst ATM module can include LECs
for multiple ELANs; there is one LEC for each ELAN of which it is a member.
LANE server (LES)--The LES is the control center for an ELAN. It provides joining, address
resolution, and address registration services to the LECs in that ELAN. LECs can register destination
unicast and multicast MAC address with the LES. The LES also handles LANE Address Resolution
Protocol (LE_ARP) requests and responses and maintains a list of route descriptors that is used to
support source-route bridging (SRB) over ELANs. The route descriptors are used to determine the
ATM address of the next hop in the frame's routing information field (RIF).
Benefits