Internetworking(Network infrastructure)

Management of interconnected heterogeneous networks

LAN - LAN

LAN - WAN

WAN - WAN

LAN -WAN- LAN

Internetworking Devices

1. Repeater( Layer 1 )

2. Bridge( Layers 1, 2 )

3. Router( Layers 1, 2, 3 )

(=Gateway)--Internet used to call routers as gateways

4. Gateway( All layers)(=Protocol Converter )

1. Repeater

- Layer 1 device--simple regeneration of received bits

- Sometimes called as “Transceivers”--Transmitter-Receiver for connecting

different media types--T-to-2 repeater, 5-to-2 repeater, ….

- Used to extend the media in Same types of LANs only

- Usually Same speed--there are ones with different speed--10BaseT-to-100BaseT repeater

- Small LANs

- Repeaters only extends the length of media--still in one “Collision Domain”

10Base5 to 10Base2 repeaters

10Base2 to 10BaseT repeaters

2. Bridge

- Operates on Layers 1 & 2

Bridge connecting 802.3 & 802.5

- Can connect Same types of LANs(Ethernet to Ethernet, Token Ring to Token Ring, ,,)

or connect Different LANs(Ethernet to Token Ring, ….)

- Can operate on Same/Different Speed

From: http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/bridging.htm “Upper layer protocol transparency is a primary advantage of both bridging and switching. Because both device types operate at the link layer, they are not required to examine upper-layer information. This means that they can rapidly forward traffic representing any network-layer protocol. It is not uncommon for a bridge to move AppleTalk, DECnet, TCP/IP, XNS, and other traffic between two or more networks.”

Bridges for connecting Similar LANs(ENET-to-ENET, T-Ring-to-T-Ring,

FDDI-to-FDDI, …)

Two kinds of Bridges

- Transparent Bridges

- Source Routing Bridges

TB(Transparent Bridge)

Example:Wireless Ethernet Bridge

- Used for Ethernets

- called Learning Bridge

Bridges have more than 2 Ethernet cards--called “ports”

Bridge puts its Ethernet cards in “Promiscuous mode”(=Listen Everything mode) and

Listens to every frame on the local wire

Whenever a local station sends a frame, the bridge learns(keeps in a table) the MAC address of the station

If bridge sees a frame going to a station whose address is not in its table, then it forwards the frame to the other wire(bridge port)

Also Broadcast frames(Ethernet Destination address of all 1’s--FF:FF:FF:FF:FF:FF) are sent to every port

**********The following is For Your Information**********

From http://www.lex-con.com/protocols/en-bcast.txt

****************************************************************************
*** Ethernet Broadcast Addresses Updated 12/2/98 ***
****************************************************************************
 
Ethernet Type 
Address Field Usage
------------------ ----- -------------------------------------------------
FF-FF-FF-FF-FF-FF 0600 XNS packets, Hello or gateway search?
 6 packets every 15 seconds, per XNS station
FF-FF-FF-FF-FF-FF 0800 IP (e.g. RWHOD via UDP) as needed
FF-FF-FF-FF-FF-FF 0804 CHAOS
FF-FF-FF-FF-FF-FF 0806 ARP (for IP and CHAOS) as needed
FF-FF-FF-FF-FF-FF 0BAD Banyan
FF-FF-FF-FF-FF-FF 1600  VALID packets, Hello or gateway search?
 1 packets every 30 seconds, per VALID station
FF-FF-FF-FF-FF-FF 8035 Reverse ARP
FF-FF-FF-FF-FF-FF 807C Merit Internodal (INP)
FF-FF-FF-FF-FF-FF 809B EtherTalk
FF-FF-FF-FF-FF-FF 9001 3Com (ex Bridge) Name Service
FF-FF-FF-FF-FF-FF 9002 3Com PCS/TCP Hello, Approx. 1 per minute per w/s
 
****************************************************************************
*** Ethernet Multicast Addresses Updated 12/2/98 ***
****************************************************************************
 
Ethernet Type 
Address Field Usage
------------------ ----- -------------------------------------------------
01-00-0C-CC-CC-CC -802- CDP (Cisco Discovery Protocol), VTP (Virtual 
 Trunking Protocol)
01-00-0C-DD-DD-DD ???? CGMP (Cisco Group Management Protocol)
01-00-10-00-00-20 -802- Hughes Lan Systems Terminal Server S/W download
01-00-10-FF-FF-20 -802- Hughes Lan Systems Terminal Server S/W request
01-00-1D-00-00-00 -802- Cabletron PC-OV PC discover (on demand)
01-00-1D-42-00-00 -802- Cabletron PC-OV Bridge discover (on demand)
01-00-1D-52-00-00 -802- Cabletron PC-OV MMAC discover (on demand)
01-00-3C-xx-xx-xx ???? Auspex Systems (Serverguard)
01-00-5E-00-00-00 0800 DoD Internet Multicast (RFC-1112)
 through
01-00-5E-7F-FF-FF
01-00-5E-80-00-00 ???? DoD Internet reserved by IANA
 through
01-00-5E-FF-FF-FF
01-00-81-00-00-00  ???? Synoptics Network Management
01-00-81-00-00-02 ???? Synoptics Network Management
01-00-81-00-01-00 -802- (snap type 01A2) Bay Networks autodiscovery
01-00-81-00-01-01 -802- (snap type 01A1) Bay Networks autodiscovery
01-20-25-00-00-00 873A Control Technology Inc's Industrial Ctrl Proto.
 through
01-20-25-7F-FF-FF
01-80-24-00-00-00 8582 Kalpana Etherswitch every 60 seconds
01-80-C2-00-00-00 -802- Spanning tree (for bridges)
01-80-C2-00-00-01 -802- 802.1 alternate Spanning multicast
 through
01-80-C2-00-00-0F
01-80-C2-00-00-10 -802- Bridge Management
01-80-C2-00-00-11 -802- Load Server
01-80-C2-00-00-12 -802- Loadable Device
01-80-C2-00-00-14 -802- OSI Route level 1 (within area) IS hello?
01-80-C2-00-00-15 -802- OSI Route level 2 (between area) IS hello?
01-80-C2-00-01-00 -802- FDDI RMT Directed Beacon
01-80-C2-00-01-10 -802- FDDI status report frame
01-DD-00-FF-FF-FF 7002 Ungermann-Bass boot-me requests
01-DD-01-00-00-00 7005 Ungermann-Bass Spanning Tree
 
 [ The following block of addresses are used on Token Ring for ]
 [ group addresses of Token Ring specific functions, reference ]
 [ ISO 8802-5:1995 aka. IEEE 802.5:1995 for some info. These ]
 [ in the Ethernet order for this list. On Token Ring they ]
 [ appear reversed. They should never appear on Ethernet. ]
 
03-00-00-00-00-01 -802- NETBIOS
03-00-00-00-00-02 -802- Locate - Directory Server
03-00-00-00-00-04 -802- Synchronous Bandwidth Manager
03-00-00-00-00-08 -802- Configuration Report Server
03-00-00-00-00-10 -802- Ring Error Monitor
03-00-00-00-00-20 -802- Network Server Heartbeat
03-00-00-00-00-40 -802- Ring Parameter Monitor
03-00-00-00-00-80 -802- Active Monitor
03-00-00-00-04-00 -802- LAN Manager
03-00-00-00-08-00 -802- Ring Wiring Concentrator
03-00-00-00-10-00 -802- LAN Gateway
03-00-00-00-20-00 -802- Ring Authorization Server
03-00-00-00-40-00 -802- IMPL Server
03-00-00-00-80-00 -802- Bridge
03-00-00-01-00-00 -802- user-defined
 through 
03-00-40-00-00-00 -802-
 
 [ End of Token Ring only block...note that the next two overlap ]
 
03-00-00-00-00-10 80D5 (OS/2 1.3 EE + Communications Manager)
03-00-00-00-00-40 80D5 (OS/2 1.3 EE + Communications Manager)
09-00-02-04-00-01? 8080? Vitalink printer messages
09-00-02-04-00-02? 8080? Vitalink bridge management
09-00-07-00-00-00 -802- AppleTalk Zone multicast addresses
 through
09-00-07-00-00-FC
09-00-07-FF-FF-FF -802- AppleTalk broadcast address
09-00-09-00-00-01 8005 HP Probe
09-00-09-00-00-01 -802- HP Probe
09-00-09-00-00-04 8005? HP DTC
09-00-0D-XX-XX-XX -802- ICL Oslan Multicast
09-00-0D-02-00-00 ???? ICL Oslan Service discover only on boot
09-00-0D-02-0A-38 ????  ICL Oslan Service discover only on boot
09-00-0D-02-0A-39 ???? ICL Oslan Service discover only on boot
09-00-0D-02-0A-3C ???? ICL Oslan Service discover only on boot
09-00-0D-02-FF-FF ???? ICL Oslan Service discover only on boot
09-00-0D-09-00-00 ???? ICL Oslan Service discover as required
09-00-1E-00-00-00 8019? Apollo DOMAIN
09-00-26-01-00-01? 8038 Vitalink TransLAN bridge management
09-00-2B-00-00-00 6009? DEC MUMPS?
09-00-2B-00-00-01 8039 DEC DSM/DDP
09-00-2B-00-00-02 803B? DEC VAXELN?
09-00-2B-00-00-03 8038 DEC Lanbridge Traffic Monitor (LTM)
09-00-2B-00-00-04 ???? DEC MAP (or OSI?) End System Hello?
09-00-2B-00-00-05 ???? DEC MAP (or OSI?) Intermediate System Hello?
09-00-2B-00-00-06 803D? DEC CSMA/CD Encryption?
09-00-2B-00-00-07 8040? DEC NetBios Emulator?
09-00-2B-00-00-0F 6004 DEC Local Area Transport (LAT)
09-00-2B-00-00-1x ???? DEC Experimental
09-00-2B-01-00-00 8038 DEC LanBridge Copy packets (All bridges)
09-00-2B-01-00-01 8038 DEC LanBridge Hello packets (All local bridges)
 1 packet per second, sent by the
 designated LanBridge
09-00-2B-02-00-00 ???? DEC DNA Level 2 Routing Layer routers?
09-00-2B-02-01-00 803C? DEC DNA Naming Service Advertisement?
09-00-2B-02-01-01 803C? DEC DNA Naming Service Solicitation?
09-00-2B-02-01-09 8048 DEC Availability Manager for Distributed
 Systems DECamds
09-00-2B-02-01-02 803E? DEC Distributed Time Service
09-00-2B-03-xx-xx ???? DEC default filtering by bridges?
09-00-2B-04-00-00 8041? DEC Local Area System Transport (LAST)?
09-00-2B-23-00-00 803A? DEC Argonaut Console?
09-00-39-00-70-00? ???? Spider Systems Bridge Hello packet?
09-00-4C-00-00-00 -802- BICC 802.1 management
09-00-4C-00-00-02 -802- BICC 802.1 management
09-00-4C-00-00-06 -802- BICC Local bridge STA 802.1(D) Rev6
09-00-4C-00-00-0C -802- BICC Remote bridge STA 802.1(D) Rev8
09-00-4C-00-00-0F -802- BICC Remote bridge ADAPTIVE ROUTING
 (e.g. to Retix)
09-00-4E-00-00-02? 8137? Novell IPX (BICC?)
09-00-56-00-00-00 ???? Stanford reserved
 through
09-00-56-FE-FF-FF
09-00-56-FF-00-00 805C Stanford V Kernel, version 6.0
 through
09-00-56-FF-FF-FF
09-00-6A-00-01-00 ???? TOP NetBIOS.
09-00-77-00-00-00 -802- Retix Bridge Local Management System
09-00-77-00-00-01 -802- Retix spanning tree bridges 
09-00-77-00-00-02 -802- Retix Bridge Adaptive routing
09-00-7C-01-00-01 ???? Vitalink DLS Multicast
09-00-7C-01-00-03 ???? Vitalink DLS Inlink
09-00-7C-01-00-04 ???? Vitalink DLS and non DLS Multicast
09-00-7C-02-00-05 8080? Vitalink diagnostics
09-00-7C-05-00-01 8080? Vitalink gateway?
09-00-7C-05-00-02 ???? Vitalink Network Validation Message
09-00-87-80-FF-FF 0889 Xyplex Terminal Servers
09-00-87-90-FF-FF 0889 Xyplex Terminal Servers
0D-1E-15-BA-DD-06 ???? HP
33-33-00-00-00-00 86DD IPv6 Neighbor Discovery
 through
33-33-FF-FF-FF-FF
AB-00-00-01-00-00 6001 DEC Maintenance Operation Protocol (MOP)
 Dump/Load Assistance
AB-00-00-02-00-00 6002 DEC Maintenance Operation Protocol (MOP)
 Remote Console; 1 System ID packet every
  8-10 minutes, by every:
 - DEC LanBridge
 - DEC DEUNA interface
 - DEC DELUA interface
 - DEC DEQNA interface (in a certain mode)
AB-00-00-03-00-00 6003 DECNET Phase IV end node Hello packets
 1 packet every 15 seconds, sent by each
 DECNET host
AB-00-00-04-00-00 6003 DECNET Phase IV Router Hello packets
  1 packet every 15 seconds, sent by the
 DECNET router
AB-00-00-05-00-00 ???? Reserved DEC
 through
AB-00-03-FF-FF-FF
AB-00-03-00-00-00 6004 DEC Local Area Transport (LAT) - old
AB-00-04-00-xx-xx  ???? Reserved DEC customer private use
AB-00-04-01-xx-yy 6007 DEC Local Area VAX Cluster groups
 System Communication Architecture (SCA)
 
 [ Note, used to have a bunch of things here starting C0, but ]
 [ these were bit reversed from Ethernet order and Token Ring ]
 [ specific. See above under 03 for them in Ethernet order/ ]
 
CF-00-00-00-00-00 9000 Ethernet Configuration Test protocol (Loopback)
FF-FF-00-60-00-04 81D6 Lantastic
FF-FF-00-40-00-01 81D6 Lantastic
FF-FF-01-E0-00-04 81D6 Lantastic

*********End of Ethernet Broadcast addresses***********

Table in a brdge:

MAC Address Bridge Port#

------------------------------------------------

00:00:1D:12:98:AC P0

00:10:0A:C7:6A:6E P1

…….

Example: http://www.lanode.com/tier2/et10.htm

- Simple Plug-in

- Isolates Intra-LAN traffic(Segmentation of collision domains)

- Broadcast Prob.

- Closed loop Prob.

- Bridges run a distributed Spanning Tree Algorithm to avoid the “closed loop” problem

Developed by Radia Perlman at DEC

Now IEEE 802.1 specification

Alogrithm overview

Each bridge has a unique id

Select bridge with smallest id as root

Select bridge on each LAN that is closest to the root as that LAN’s designated bridge(use id to break ties)

Each bridge forwards frames over each LAN for which it is the designated bridge

For exchanging Spanning tree information bridges use specific addresses:

01-80-C2-00-00-00 -802- Spanning tree (for bridges)
01-80-C2-00-00-01 -802- 802.1 alternate Spanning multicast
 through
01-80-C2-00-00-0F 
01-80-C2-00-00-10 -802- Bridge Management

SRB( Source Routing Bridge )\

- Used For Token-Rings

- Relies on "intelligent hosts" than bridges

- Complete Source-to-Dest routing info. in frames

- Source computer first sends a “Test” frame--to find out if the destination station

is on the current ring

- If not then, it sends “Explorer frame”--every bridge puts the Ring number and Bridge number

in the frame and forwards to all the connections

- Multiple frame arrive at the destination station, the destination will reply to all of them

- Source receives multiple Acks from the destination and decides which route it should take

- All the ensuing frames are sent through the fixed route

- Heavy traffic due to Explorer frame

Bridges Connecting Dissimilar LANs

- Ring-- B -- Ether, Ethernet---B---FDDI, ….

- There are quite a few differences between protocols

---Bit-order trans.---MSB(Most Significant Bit) first or LSB first

---Max. length for frames different

---Priority in Token Ring but no priority in Ethernet

……

3. Router

- In old Internet terminology, current routers have been called “gateways”

- Operates on layers 1, 2, 3

- Each port of a router has a network card(Ethernet, Token Ring, FDDI, ISDN, X.25, DSL, Modem, …)

- The 3^rd layer runs either:

- Connection-Oriented--X.25 layer 3(=CCITT X.75)

OR

- Connectionless--IP

4. Gateway(=Protocol Converter )

- Operates on All layers(Layer 1 to 7)

- OSI----Gateway-----TCP/IP

- IBM SNA----Gateway----TCP/IP

- Netware-----Gateway-----Microsoft networks

The term “Gateway” can mean either of the above---Router or Protocol Converter

depending upon the usage