8. IP Over ATM

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8. IP Over ATM


Set of IP hosts within a same IP domain
(subnet) communicate with each other
directly over ATM network.


The IP hosts outside their subnet (domain)


communicate with other IP hosts in


another subnet via an IP router.





ATM Network

IP Host 1

IP Host 2

IP Host 3

IP Host 4


CASE 1:


CASE 2:





ATM Network

ATM

NETWORK

IP Router

IP Host 1

IP Host 2

IP Host 3

IP Host 4

IP Over ATM


OVERLAY MODEL


IP o癥r ATM



PEER MODEL


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LABEL 南ITCHI乇N


(MPLS)


Integrated ATM switching and IP Routing Function.


No Address Resolution Protocol.

FRAMEWORK for IP over ATM

1. Packet Encapsulation


2. Address Resolution


3. Multicasting


4. Large Network (Scalability)

DETAILED FRAMEWORK


1. How many VC’s do we need for
n

protocols?


i.e., Define a method to transport multiple types of network


or link layer packets across an ATM connection and also for


MUXing multiple packet types on the same connection.





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Packet Encapsulation [RFC 1483]


2. How to find ATM addresses from IP
addresses?


Address Resolution [RFC 1577]


DETAILED FRAMEWORK



3. How to handle multicast?




MARS

[
R䙃 2022
]



4. How do we go through
n

subnets


on a large ATM network?




NHRP

PACKET ENCAPSULATION (RFC 1483)



Goal
:

Encapsulating IP packets in
ATM AAL5 cells






LLC/SNAP Encapsulation


VC Multiplexing

(Multiprotocol Encapsulation)

(VC based Encapsulation)







(“NULL”Encapsulation)




A node that receives a network layer packet across an ATM connection to know what kind of

packet has been received, and to what application or higher level entity to pass the packet to;

hence the packet must be prefixed with a MUX field.

PACKET ENCAPSULATION (RFC 1483)







Given an ATM link between two routers with 3
different protocols.
How many VC’s shall we set up
?

IP

IPX

AppleTalk

Router

Router

ATM Switch

Different Protocols

Scenario
:

ANSWER 1
: LLC/SNAP ENCAPSULATION



Share a VC using LOGICAL LINK CONTROL (LLC)
Subnetwork Access Protocol (SNAP).


IP

IPX

Apple Talk

IP

IPX

Apple Talk


VC

Several protocols are carried over the same VC. The protocol is identified

by prefixing the IP packet with an IEEE 802.2 LLC header followed by

an IEEE 802.1a Subnet Attachment Point (SNAP) header.
Encapsulations

Terminate at the LLC layer within the end system.


LLC/SNAP ENCAPSULATION

0xAA
-
AA
-
03

0x00
-
00
-
00

0x08
-
00

IP Packet

8Byte header

AAL5 Frame

IP Packet

3Bytes

LLC

2Bytes


PID

3Bytes

OUI

An LLC
(3 bytes)

/SNAP header
(5 bytes)
is prepended to each packet to identify

which protocol is contained in the payload. PID distinguishes one protocol from

another.

0x0800 specifies IP; 0x0806 is ARP; 0x809B is AppleTalk; 0x8137 is IPX; ..

OUI


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.

Max Transfer Unit (MTU)

size is standardized at 9180 Bytes, excluding

8 Byte header. However, the size can be negotiated up to 64K Bytes.






VC MULTIPLEXING (“NULL” ENCAPSULATION)

ANSWER 2
:

IP

IPX

Apple Talk

IP

IPX

AppleTalk

VC is terminated directly at a layer 3 endpoint. In other words, the AAL endpoints

of a VC multiplexed connection would be the layer 3 protocol entities. This means

that a VC will carry one protocol only
.
No MUXing
.
LANE encapsulation is a form of VC MUXing.

VCa

VCb

VCc

Each protocol is carried over a separate VC with the protocol


type specified at connection set
-
up.



Comparison of Both Schemes


Sharing a VC limits the number of VCs required in an IP & multi
-
protocol environment


However, it uses an additional 8 Byte per AAL frame as a header.


Also an LLC/SNAP entity must be present at each endpoint to
demultiplex the frames & pass them up to the higher layer protocol


VC
-
based multiplexing is more efficient from a pure VC perspective.


VC multiplexing results in minimal bandwidth and processing overhead.


Moreover, because a single protocol is mapped to a single VC it may be
easier to perform filtering and/or authentication.


UNI Signaling is required to initiate an LLC/SNAP encapsulated SVC.



LLC/SNAP supports multiple protocols over the same VC. Permits
connection reuse & reduces connection set
-
up time.



LLC/SNAP method is the default method for IP over ATM.


ADDRESS RESOLUTION (RFC1577)



IP Address:

123.145.134.65

ATM Address: 47.0000
1 614 999 2345
.00.00.AA….



Issue:

IP Address


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⡌(gi捡l IP 卵S湥琠Co湣数琩



Address Resolution Protocol (ARP)



Inverse ATM ARP:
(ATM_ARP Server sends messages to client).



Solution:

ATMARP servers

ATMARP

Server

15

Architecture

Host

ATM_ARP

Server

Host

Host

Host

Host

Host

ATM_ARP

Server

ATM_ARP

Server

IP Router

IP Router

Logical

IP

Subnet 1

Logical

IP

Subnet 2

Logical

IP

Subnet 3

LIS

LIS

LIS

Architecture (Cont.)


Hosts on subnet are assigned an
IP address

and
PHY layer


address (ATM).



IP nodes (end
-
systems and routers) in the ATM network are


grouped into logical IP subnets (LIS) (with
similar subnet
addresses).



The nodes in one LIS communicate with those outside their


LIS through IP routers.



When communicating with another host on the same subnet


using ATM, it is necessary to resolve the destination IP


address with the ATM address of the end
-
point.


Architecture (Cont.)



When traversing subnet boundaries, it is necessary


to first pass through a IP router which can


continue to implement any filtering, access or


security policies.

Architecture (cont.)


Within each LIS, there is an ATM Address
Resolution Protocol Server (ATM_ARP) which
performs directory services function for the nodes
in the LIS.



A single LIS can support many hosts and routers
with the same IP network & subnet mask.



Communication between any two members of the
LIS takes place over ATM PVC or SVC.


Configuration Requirements

(Intra
-
subnet)





(ATM Network)

LIS 1

ATM ARP Server

LIS 2

ATM Network

IP Router

ATM ARP Server

IP Host 1

IP Host 2

IP Host 3

IP Host 4


Configuration Requirements (Cont.)


All LIS members must use
ATMARP and InATMARP

in
conjunction with an ATMARP server entity to resolve IP and
ATM addresses

when using SVCs
.



All LIS members must use
InATMARP

to resolve VCs to IP
addresses
when using PVCs
.

An ATMARP server entity is not
required when using PVCs.



All LIS members must be able to communicate with all other
LIS members using an ATM PVC or SVC. This implies that the
underlying ATM fabric can be fully meshed.



Configuration Requirements (Cont.)

The following ATM parameters must be configured for each
member of the LIS:




ATM Hardware Address

:

This is the ATM address of the
individual IP host.




ATMARP Request Address

:

This is the ATM address of the
ATMARP server for the LIS. If the LIS is using only PVCs,
then this requirement may be null.


ATMARP SERVER


Primary purpose is to maintain a table or cache of IP address mappings.


At least one ATMARP server must be configured for each LIS, along with a
specific IP and ATM address.


A single ATMARP server may service more than one LIS as long as it is IP and
ATM addressable within each LIS.


An ATMARP server learns about the IP and ATM addresses of specific members
(IP clients) of the LIS through the use of ATMARP and InATMARP messages
exchanged between the ATMARP server and LIS members.


Finally, an ATMARP server can run on an IP host or router.



Figure shows an LIS with 2 IP clients and a stand
-
alone ATMARP server.

ATM

Switch

IP Client# 1

IP address=176.13.11.1

ATM address=AAA

IP Client# 2

IP address=176.13.11.2

ATM address=BBB

ATMARP server

IP address=176.13.11.99

ATM address=ZZZ


ATMARP SERVER (Cont.)

The ATMARP protocol is composed of
five unique message types
.

ATMARP Message

Description

ATMARP request

ATMARP reply

InATMARP reply

InATMARP request

ATMARP NAK

Sent from IP client to server to obtain destination ATM address, contains the

client’s IP address, ATM address, and the destination’s IP address

Response from server to IP client with destination ATM address, contains the

client’s and destination’s IP and ATM addresses

Sent from server to IP client over VC to obtain IP address, contains the client’s

ATM address and the ATMARP server’s IP and ATM addresses

Response from IP client over VC with IP address, contains the client’s and

Server’s IP and ATM addresses

Negative response to ATMARP request sent from server to IP client

Registration



IP clients must first register their IP and ATM addresses with the
ATMARP server.



This is performed by the IP client who initially establishes an SVC with
the ATMARP server.



The IP client is able to do this because it is configured with the ATM
address of the ATMARP server.



Next the ATMARP server sends out an InATMARP request.



The purpose of this message is to obtain the IP address of the client.



The client returns an InATMARP reply which will contain both the IP
and ATM addresses of the client.



The ATMARP server checks its existing table and if there are no
duplicates, time
-
stamps the entry and adds it to the table.



This entry is valid for a minimum of 20 minutes.




Registration



The registration process flow for IP Client #1 is shown in
Figure.



Of course, IP Client #2 will register its own address with the
ATMARP server once it is initialized.

ATM
Switch

Setup VC

InATMARP_Req (IP addr of client #1???)

InATMARP_Reply (176.13.11.1)

IP address=176.13.11.99
ATM address=ZZZ

ATMARP
Server

IP Client #1
IP address=176.13.11.1
ATM address=AAA

IP Client #2
IPaddress=176.13.11.2
ATM address=BBB

A new client wants to join


Client Comes Up (Registers)


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the ATMARP Server of its own LIS.

ATMARP Server detects the connection from the new client,
sends an
inverse ARP

request using the clients ATM address to
request clients’
IP address

since it knows clients ATM address
through VC connection.

Client

ATM_ARP Server

Inverse ARP


ADDRESS RESOLUTION



If IP Client #1 wishes to communicate with IP Client #2 and a
connection already exists, then the packets will immediately flow
over that connection.




IP Client #1 may contain the ATM address of IP Client #2 in its
own ARP cache and if so, then it can immediately set up an SVC
to IP Client #2.




However, if a connection does not already exist and IP Client #1
does not know the ATM address of IP Client #2, then the ATMARP
process is invoked.




IP Client #1 sends an ATMARP request to the ATMARP server
that contains the
source IP address
,
destination IP address
, and
source ATM address
.





ADDRESS RESOLUTION



If the ATMARP server contains an IP/ATM address entry for IP Client #2,
it will return that information in an ATMARP reply message.




IP Client #1 then knows the ATM address of IP Client #2 and can set up
an SVC.




If not, then the ATMARP server will return an ARP NAK message.

ATM

Switch

IP Client# 1

IP address=176.13.11.1

ATM address=AAA

IP Client# 2

IP address=176.13.11.2

ATM address=BBB

ATMARP server

IP address=176.13.11.99

ATM address=ZZZ

ATMARP_Req (IP addr of Client #2, ATM addr ???)

ATMARP_Reply (ATM addr = BBB)

Setup VC and Send Data

29

Example
:


Client in LIS 1 wants to communicate with a client in LIS 2
must go through ROUTER 1 even though a direct VC can
be established between two clients over the ATM network.


Two clients are attached to two different ATM switches.


Within this LIS



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-
ARP⁳er癥r.


Each node is configured with the ATM address of its
ATM_ARP server.



Host 1 establishes a connection to its LIS ATM_ARP Server
and then resolves an address for Host 2 in the same LIS.

ATM_ARP

Server

Destination

Switch

Source

Switch

Host 2

Host 1

Set Up

Set Up

Connect

Connect

Connection Established

InARP request

InARP RP

ARP Request

ARP Response

Set Up

Set Up

Set Up

Connect

Connect

Connect

Connection Established

Registration

Address

Resolution

Connection

Establishment

Operation of Classical IP over ATM


REVIEW:

Suppose:
A host S wants to use CLIP (Classical IP over ATM) to send packets

to another host D wthin the same LIS. S knows only the IP address of D. To set up
a VCC through ATM. How does S resolve ATM address of D?





(ATM Network)

LIS 1

ATM ARP Server

LIS 2

ATM Network

IP Router

ATM ARP Server

IP Host 1

IP Host 2

IP Host 3

IP Host 4

Reminder (Pure IP Case):


IP uses the CLASS D address space to send packets to
the members of a multicast group.



Host and routers exchange messages using a group
membership protocol called the
Internet Group
Management Protocol (IGMP).



The routers use the results of this message exchange
along with a multicast routing protocol
such as MOSPF

to build a delivery tree from the source subnetwork to
all other subnetworks that have members in the
multicast group.

IP Multicasting
over

ATM


Multicast Address Resolution Server

(MARS)

(Analog to the ATMARP Server that supports
multicast address resolution)


IP Multicasting
over

ATM





IP hosts attached to an ATM network utilize the MARS


to track and disseminate information about multicast


group membership.




IP multicast senders may query the MARS when


multicast address needs to be resolved with the ATM


address(es) of the IP hosts participating in the group.


IP Multicasting
over

ATM (Ctd)


The concept of a
CLUSTER

is used to define ATM hosts (or
routers) that are participating in an ATM level multicast and
that share a MARS.



A cluster is mapped to a single LIS but it is possible to extend
the MARS to support a single cluster over multiple LISs.




However, that would require support for multicast routing (e.g.,
MOSPF, PIM) over ATM, which is an area that requires further
study.



So for now consider a one
-
to
-
one relationship between LIS and
CLUSTER
.

The following should also be noted about the MARS:




But instead of maintaining a table of IP to ATM


address pairs, it holds an extended table consisting


of IP group addresses and then the ATM addresses


of the specific
CLUSTER MEMBERS
.


This is called a
HOST MAP.




For example, an entry for members belonging


to multicast group 232.200.200.1 might look like:

{232.200.200.1, ATM Address 1, ATM
Address 2, …, ATM Address N}

Example:
A Cluster with a MARS & 3
Cluster Members or MARS Clients

MARS

LIS

A.1

A.2

A.3

Pt
-
Pt VC between IP client and MARS

Pt
-
Mpt ClusterControlVC


Clients who wish to participate in a multicast group
establish a point
-
to
-
point VC with the MARS.


Clients register with the MARS by sending a
MARS_JOIN message containing the “all nodes” group
address (224.0.0.1) as described in RFC 1112.


The MARS will then add the client as a leaf on its
ClusterControlVC.



The
ClusterControlVC

is a point
-
to
-
multipoint VC that
is established between the MARS and all multicast
-
capable cluster members (hosts or routers).


The
ClusterControlVC

is used by the MARS to
distribute group membership updates to all members of
the cluster.


For example, after host A.2 registers, the MARS will send a
MARS_JOIN

message out over its
ClusterControlVC

to all
members, indicating that host A.2 has registered and is
multicast
-
capable.


Clients who wish to join or leave a specific multicast group
will send a
MARS_JOIN

or
MARS_LEAVE

message to the
MARS containing one or more IP group addresses.


Again, this information will be propagated to other cluster
members over the
ClusterControlVC

so that sources (roots)
can add to or prune their multicast trees.


Clients send a
MARS_REQUEST

to the MARS seeking
address resolution of a specific IP group address.


MARS responds with a
MARS_MULTI

message which
contains the
HOST MAP

for the IP group address.

MARS


LIS

A.2

A.3

A.1

Example


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MARS
-
REQUEST and MARS
-
MULTI Flows



Hosts A.2 and A.3 forward
MARS_JOIN

messages up to
the MARS indicating they wish to join multicast group
XYZ.



The MARS redirects these messages out over the
ClusterControlVC
.



Host A.1 wishes to send packets to group address XYZ.



It issues a
MARS_REQUEST

message to the MARS
which returns a
MARS_MULTI

message that contains a
HOST MAP

of (XYZ,A.2,A.3).



A.1 now has sufficient information to establish a point
-
to
-
multipoint VC with the group members A.2 and A.3, and
will begin multicasting.


Next Hop Resolution Protocol (for Inter
-
Subnets)

(NHRP: pronounced nerp)


LIS

(ATM
Network)

LIS

(ATM
Network)

Hos
t

Hos
t

Router

Go through a router that is a member of multiple logical IP


subnets. This router may become a bottleneck.


Solution
NHRP


ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

Data

VC

Subnet X

Subnet Y

Subnet Z

Router

Router



Main Objective:
Find the most efficient shortcut path
through ATM network so that intermediate IP routers can be
bypassed.



Recall
: Previously an IP router had to forward packets
between 2 LISs.
CLIP model resolves only the ATM address
that belongs to the same LIS. CLIP model requires an IP
router to perform packet forwarding between two different
LISs.




NHRP:
provides shortcuts to traverse multiple LISs making
it more suitable for larger networks.

NHRP (Addendum)




It is an address resolution technique for resolving IP addresses
with ATM addresses in a multiple subnet environment.



The purpose of NHRP is to provide a host or router with the
ATM address of a destination IP address so that one or more
layer
-
3 hops can be bypassed by using a direct connection over
the ATM network.



NHRP can be considered an extension to the ATMARP process
described in RFC1577.



Whereas ATMARP is used to map IP and ATM addresses in a
single LIS, NHRP is used to map IP and ATM addresses in a
multiple LIS environment contained within a single ATM network
.

NHRP


1.
NON
-
BROADCAST MULTI
-
ACCESS NETWORK (NBMA)

An NBMA network is defined as:

* Does not support an inherent broadcast or multicast capability.

* Enables any host (or router) attached to the NBMA network to
communicate directly with another host on the same NBMA network.


ATM, Frame Relay, SMDS, and X.25 are all examples of NBMA
networks. An NBMA ATM network may contain one or more LISs.

* The NBMA is partitioned into administrative domains.




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* Each LNS is served by an
NHS (Next Hop Server)



NHRP Terminology

2. NEXT HOP SERVER (NHS)

(These are responsible for answering NHRP resolution
requests by means of NHRP replies.)



NHS serves a set of hosts (or NHRP stations) in the NBMA network and answers
NHRP resolution requests from these stations
called NHC (Next Hop Clients).



Both NHS and NHC

contain a
CACHE

or table of IP & ATM addresses for devices
attached to the ATM network (
Address Resolution Cache).



If the desired destination IP address is not on the ATM network, then the NHS will
provide the ATM address of the router nearest to the destination.



The NHS should run on a router so as to facilitate forwarding of NHRP requests,
replies, and other messages over the default
-
routed path.



The NHS responds to queries from NHRP clients.



The NHS serves a specific set or domain of NHRP clients for whom it is
responsible.


NHRP Terminology (Cont.)

3. NEXT HOP CLIENTS (NHC)



NHRP cloud contains entities called NHCs.



These are responsible for initiating NHRP resolution


request packets.

REMARK:



Both NHC and NHS maintain an ADDRESS RESOLUTION


CACHE.



An NHC in NHRP replaces an ATMARP client in CLIP


(Classical IP over ATM Case)



NHS replaces an ATMARP server.


NHRP Terminology (Cont.)



NHRP clients must be attached to an ATM network and


must be configured with the ATM address of the NHS


that is serving the client. Alternatively, it should have a


means of locating its NHS.




Techniques under consideration involving other server


location requirements such as ATMARP and MARS are


a group address and a configuration server.




NHRP can run on an ATM
-
attached host or router.


The NHS will likely be located on a station’s peer or


default router.

NHRP Configuration



NHRP clients can be serviced by more than one NHS.



NHRP Servers are configured with their own IP and ATM
addresses, a set of IP address prefixes that correspond to the
domain of NHRP clients it is serving, and an NBMA (ATM)
network identifier.



If the NHRP server is located on an egress router attached
to a non
-
ATM network, then the NHRP server must exchange
routing information between the ATM and non
-
ATM
network.

NHRP Configuration (Cont.)



NHRP clients register with their NHRP server in one of the
two ways:


1
-

Manual Configuration

2
-

NHRP Registration Packets



The NHRP registration packet contains the following
information along with additional values:

{NHC’s ATMaddress, NHC’s IPaddress, NHS’s IPaddress}



With this information, the NHRP server can begin to build
its table of IP and ATM addresses.


NHRP Client Registration

NHRP Client Registration

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

ATM

Switch

Subnet

X

Subnet

Y

Subnet

Z

NHS X

NHS Z

X.1

Z.3

NHRP Registration Request

NHRP Registration Reply

NHRP Registration Request

NHRP Registration Reply

NHRP ADDRESS RESOLUTION

NHS X

NHS Z

Subnet X

ATM
Switch

ATM
Switch

ATM
Switch

ATM
Switch

ATM
Switch

ATM
Switch

ATM
Switch

ATM
Switch

ATM
Switch

ATM
Switch

ATM
Switch

ATM
Switch

Subnet Y

Subnet Z

X.1

Z.3

IP address = X.1

ATM address = AAA

IP address = Z.3

ATM address = BBB

First Packet

First Packet

First Packet

NHRP Resolution Request

NHRP Resolution Request

NHRP Resolution Reply

NHRP Resolution Reply

Setup SVC

Data

A single NBMA ATM network that contains 2 LISs: X and Z. Actually 3 if we
count the LIS connecting the two routers omitted.

NHRP ADDRESS RESOLUTION



Station X.1 builds a packet and addresses it to Z.3.


If Z.3 ATM address known, then X.1 uses an existing VCC to send its data.


If not, I.e., X.1 does not know the ATM address of Z.3, then it sends NHRP.


This packet is forwarded over an existing ATM VC to the default router.


This causes X.1 to send a NHRP Next Hop Resolution Request message to NHS
X with the following information: [AAA, X.1, Z.3].


Station X.1 may also opt to hold onto the packet until a NHRP reply is received
or drop it.


The first option, the default, is the better choice because that allows data to
flow over the default
-
routed path.



The LISs are connected by two routers that serve as NHRP servers


for subnets X and Z, respectively.



The routers are running a normal intra
-
AS routing protocol, OSPF, and


are connected by an ATM PVC so they are exchanging routing


information.



The station attached to subnet X with the IP address of X.1 wishes


to communicate with station Z.3.

NHRP ADDRESS RESOLUTION



NHS X checks to see if it serves station Z.3.


It also checks to see if it has an entry in its cache for Z.3.


SUPPOSE

Neither is true so the NHRP (Next Hop Resolution
Request) is forwarded to the adjacent NHRP server, NHS Z.


NHS Z receives the NHRP Next Hop Resolution Request from NHS X.


NHS Z determines that it serves the destination IP address contained
in the request message.


An entry is contained in the cache or table of NHS Z which contains an
IP to ATM address mapping for the destination IP address of Z.3.


NHS Z resolves the destination IP address, Z.3, with its matching ATM
address, BBB.



It places this information in a NHRP Next Hop Resolution Reply and
returns it to station X.1 over a default
-
routed path that the request
came from.


The NHRP Next Hop Resolution Reply could flow directly back to the
initiator X.1 if


(1)
A VC exists between station X.1 and NHS Z,

(2)
An NHRP Reverse NHS record Extension is not included in the
request message, and

(3)
The authentication policy permits direct communication between the
initiator, station X.1, NHS Z.

(4)
Sending a direct response back to the NHRP initiator may save time
but does not enable any of the intermediate NHSs to cache information
contained in the NRP Next Hop Resolution Reply messages.

NHRP ADDRESS RESOLUTION



As the NHRP Resolution Reply flows back to station X.1,
NHS X may
cache the information contained in the packet.



This means it could add the entry of [Z.3, BBB] into its cache.

NHRP ADDRESS RESOLUTION



This information could be used by NHS X to provide a
non
-
authoritative

NHRP Next Hop Resolution Reply for another
station on subnet X that wishes to communicate
DIRECTLY
WITH STATION Z.3.




An authoritative NHRP Next Hop resolution reply is the one
that is generated

by the NHS that
directly
serves the NHRP
client.





If a NHRP client generates an
authoritative resolution
request
, then only the serving NHS can respond
authoritatively.





If a NHRP client generates a
non
-
authoritative resolution
request
, then any NHS that can resolve the request can
respond.



NHRP ADDRESS RESOLUTION



Nonauthoritative reply speeds up the Address Resolution
Process.




However, we need to increase the CACHE SIZE requirement
at the NHS.




Another disadvantage is that when IP
-
ATM address binding
at the destination changes, a transit NHS will respond with a
wrong address resolution reply.


NHRP ADDRESS RESOLUTION



Station X.1 will receive a NHRP Next Hop


Resolution Reply and take two actions,



(1) Cache the information contained in


the reply and



(2) Establish an ATM SVC directly to station


Z.3 and begin data transmission
.

REINVENTING IP over ATM


Ipsilon Networks



I倠Switching


Toshiba



C敬l Switching Rout敲


Cisco



Tag Switching


IBM



䅧Ar敧at攠Rout攠䉡s敤 I倠Switching (䅒IS)


IETF


M偌S (Multi偲Ptocol Lab敬 Switching)

Difference of LANE and IP over ATM


LANE hides the layers above layer 2 from ATM fabric.


Consequent Applications running over a LANE network cannot take
advantage of QoS capabilities of the ATM.

LANE

Address Resolution Process Overhead is high.


IP Address



MAC Layer Address Mapping

MAC Layer Address

ATM Address Mapping

IP over ATM

ATM_ARP Server only


IP Address

ATM Address


Mapping of Integrated Services
Internet into ATM

Application

RSVP

PIM

Flow

Specs

Flow

IDs

Packet
Scheduling

Traffic

Management

VPI/VCI

Traffic

Contract

VC

Routing

ATM

Signaling

Integrated
Service
Internet

ATM