3Com Router User Manual

							Typical DLSw Configuration Example397
II. Networking Diagram
Figure 139   Networking diagram of DLSw configuration of LAN-LAN
III. Configuration Procedure
1Router A Configuration:
[Router] dlsw local 10.120.25.1
[Router] dlsw remote 10.120.5.2
[Router] dlsw bridge-set 5
[Router] interface ethernet 0
[Router-Ethernet0] bridge-set 5
2Router B Configuration:
[Router] dlsw local 10.120.5.2
[Router] dlsw remote 10.120.25.1
[Router] dlsw bridge-set 7
[Router] interface ethernet 0
[Router-Ethernet0] bridge-set 7
Thus, the two LANs across WAN are connected together. Note that we dont list 
the related IP commands here, but you have to make sure that IPs of the 
configured local-peer and remote-peer can be intercommunicated each other. The 
notes apply for the following sections.
DLSw Configuration of 
SDLC-SDLCI. Networking Requirement
The two SDLCs across WAN are connected together by using SDLC-SDLC working 
mode.
Ethernet Ethernet
Router A
LLC2
IBM AS/ 400PC(SNA)
WAN (IP)
Router B
LLC2
10.120. 25.110.120.5.2 
						

							398CHAPTER 25: CONFIGURING DLSW
II. Networking Diagram
Figure 140   Networking diagram of DLSw configuration of SDLC-SDLC
III. Configuration Procedure
1Router A Configuration:
[Router] dlsw local 110.87.33.11
[Router] dlsw remote 202.39.28.33
[Router] dlsw bridge-set 1
[Router] interface serial 0
[Router-Serial0] link-protocol sdlc 
[Router-Serial0] baudrate 9600
[Router-Serial0] code nrzi
[Router-Serial0] sdlc status secondary
[Router-Serial0] sdlc mac-map local 00-00-11-11-00-00
[Router-Serial0] sdlc controller c1
[Router-Serial0] sdlc mac-map remote 00-00-22-22-00-c1 c1
[Router-Serial0] bridge-set 1
2Router B Configuration:
[Router] dlsw local 202.39.28.33
[Router] dlsw remote 110.87.33.11
[Router] dlsw bridge-set 1
[Router] interface serial 1
[Router-Serial1] link-protocol sdlc 
[Router-Serial1] baudrate 9600
[Router-Serial1] code nrzi
[Router-Serial1] sdlc status primary
[Router-Serial1] sdlc mac-map local 00-00-22-22-00-00
[Router-Serial1] sdlc controller c1
[Router-Serial1] sdlc mac-map remote 00-00-11-11-00-c1 c1
[Router-Serial1] bridge-set 1
Transform Configuration 
from SDLC-LAN Remote 
End Media to DLSwI. Networking Requirement
This example is a typical transform configuration from SDLC-LAN to DLSw and 
SDLC includes multipoint support function. Among this, the connected node C1 
and C2 are nodes of PU2.0 type (ATM) and C3 is node of PU2.1 type (OS2). The 
port connected to multiplexer uses NRZ encoding mode and the port connected 
separately uses NRZI encoding mode.
Router A
SDLC
IBM AS/400PC(SNA)
SDLC address
0xC1
WAN(IP)
Router B
SDLC
110.87.33.11202.39.28.33 
						

							Typical DLSw Configuration Example399
II. Networking Diagram
Figure 141   Networking Diagram of SDLC-LAN
III. Configuration Procedure:
1Router A Configuration:
[Router] dlsw local 110.87.33.11
[Router] dlsw remote 202.39.28.33
[Router] dlsw bridge-set 1
[Router] interface ethernet 0
[Router-Ethernet0] bridge-set 1
2Router B Configuration:
[Router] dlsw local 202.39.28.33
[Router] dlsw remote 110.87.33.11
[Router] dlsw bridge-set 1
[Router] interface serial 0
[Router-Serial0] link-protocol sdlc
[Router-Serial0] baudrate 9600
[Router-Serial0] sdlc status primary
[Router-Serial0] sdlc mac-map local 00-00-12-34-56-00
[Router-Serial0] sdlc controller c1
[Router-Serial0] sdlc xid c1 03e00001
[Router-Serial0] sdlc mac-map remote 00-14-cc-00-54-af c1
[Router-Serial0] sdlc controller c2
[Router-Serial0] sdlc xid c2 03e00002
[Router-Serial0] sdlc mac-map remote 00-14-cc-00-54-af c2
[Router-Serial0] bridge-set 1
[Router-Serial0] interface serial 1
[Router-Serial1] link-protocol sdlc
[Router-Serial1] baudrate 9600
[Router-Serial1] code nrzi
[Router-Serial1] sdlc status primary
[Router-Serial1] sdlc mac-map local 00-00-22-22-00-00
[Router-Serial1] sdlc controller c3
[Router-Serial1] sdlc mac-map remote 00-14-cc-00-54-af c3
[Router-Serial1] bridge-set 1
Note that MAC address of partner is the same as MAC address of AS/400 network 
card when configuring router B, but the word digital order on Ethernet and 
Token-Ring are reversed, thus you should reverse the MAC addresses to configure 
them. If the other part is Token-Ring, then you do not need to reverse it. In the 
Ethernet
Router A
IBM AS/400PC1(SNA)
SDLC address
0xC1
WAN(IP)
Router B
SDLC
110.87.33.11202.39.28.33
00-28-33-00-2a-f5
PC2(SNA)
SDLC address
0xC2
 multiplexer
PC2(SNA)
SDLC address
0xC3
SDLC 
						

							400CHAPTER 25: CONFIGURING DLSW
above example, c1 and c2 are the equipment of PU2.0 type, and c3 is the 
equipment of PU2.1 type.
Diagnosis and 
Troubleshooting of 
DLSw FaultThe normal communication of DLSw requires the sound coordination between the 
two SNA equipments and two routers operating DLSw, which participate in the 
communication. Problem in the co-ordination between any of the two points is 
likely to result in failure in connection.
Fault 1: TCP channel can not be created. The status shown is DISCONNECT 
when using command display dlsw remote. 
Creating TCP channel is the first step for the successful connection of DLSw. If TCP 
connection cant be established, the problem lies between the two routers. 
Generally, the problem is the configuration of IP address of the router. You can 
check if the IP address of remote-peer is accessible by the ping command with the 
source address. Also you can use display ip routing-table command to see if there 
is any route to the network segment. TCP connection can be created once both 
parties have established correct routes.
Fault 2: circuit can not be created correctly. To display dlsw circuits, the 
virtual circuit cant attain CONNECTED state.
There are many causes that circuit cant be created. First of all, please make sure 
that TCP connection to the opposite end is successfully established. If TCP 
connection can be established successfully, while circuit can t be created, this is 
generally caused by the problem in the coordination of the router and SNA 
equipment, mainly the problem of SDLC configuration.
Firstly, open the debugging switch of SDLC to observe if the SDLC interface can 
receive and send messages successfully. You can use display interface command to 
observe the condition of receiving and sending messages on the interface. If the 
messages cant be received and sent correctly, it is generally because something is 
wrong with the encoding mode of the interface, baud rate or clock configuration.  
Generally, this can be solved by modifying the interface configuration parameter 
of the router or adjusting the configuration parameter of SDLC equipment.
If the messages can be received and sent correctly, please check if the 
configuration PU type is correct. You can use sdlc xid command to configure XID, 
changing the setup of PU type.
If the messages can be received and sent correctly, you can check with display dlsw 
circuits verbose command to see if the virtual circuit can enter into CIRCUIT_EST 
status. If CIRCUIT_EST is not accessible all the time, it suggests that something is 
wrong with the coordination between the MAC address and the partner 
configured. Generally, this can be solved by modifying configuration parameters 
such as sdlc partner.
If circuit can attain CIRCUIT_EST state, but can not attain CONNECTED state, it 
suggests that the SDLC configuration of the router and the configuration of SNA 
equipment are not matching. Check the configuration of SDLC equipment on 
both ends and the configuration of the router to see if the configuration of the 
XID of SNA equipment (PU2.1) and the configuration of XID of the router (PU2.0) 
are correct. If nothing is wrong with the configuration, check the SDLC line on the  
						

							Diagnosis and Troubleshooting of DLSw Fault401
active equipment of SDLC (such as AS/400 or S390) is activated. Sometimes, 
communication can be implemented after you activate SDLC line manually. 
						

							402CHAPTER 25: CONFIGURING DLSW 
						

							VI
ROUTING
Chapter 26IP Routing Protocol
Chapter 27Configuring Static Routes 
Chapter 28Configuring RIP
Chapter 29Configuring OSPF
Chapter 30Configuring BGP
Chapter 31Configuring IP Routing Policy
Chapter 32Configuring IP Policy Routing 
						

							404 
						

							26
IP ROUTING PROTOCOL
IP Routing Protocol 
OverviewRouters are used to select the route in the Internet. A router selects a suitable path 
according to the destination host address contained in a received data packet, and 
sends the data packet to the next router. The last router on the path sends the 
data packet to the destination host.
Route and Route 
SegmentA router processes the path for transmitting a packet through a network as a 
logical route unit, referred to as a hop. For example, in 
Figure 142, a packet from 
host A to host C passes through 3 networks and 2 routers for a total of 3 hops. It 
shows that when two nodes are connected to each other by a network, they are 
separated by one hop and are neighbors on the Internet. Similarly, two adjacent 
routers are those connected to the same network. So, the hops from a router to 
the local network host total 0. In the diagram, the bold arrows represent the hops. 
The router does not handle data transmission through the physical links in each 
route unit.
Figure 142   Concept of route segment
Networks vary in size, so the actual length of each hop is also different. Therefore, 
for different networks, the route segments can be multiplied by a weight 
coefficient and then used to measure the length of a path.
If a router in the Internet is regarded as a node on the network, and a hop in the 
Internet is regarded as a link, then routing in the Internet is similar to that in a 
simple network. Sometimes it may not be optimal to select the route with the 
fewest hops. For example, a route passing 3 LAN hops might be much faster than 
a route passing 2 WAN hops.
Routing TablesThe routing table is essential for a router to transfer data packets. Every router has 
one routing table. The routing value in the routing table shows which physical port 

B

C

A
RR
 
Route 
Segm ent
RR
R 
						

							406CHAPTER 26: IP ROUTING PROTOCOL
of the router should be used to transfer a data packet to a sub-network or a host, 
so the packet can reach the next router on this path, or reach the host as a directly 
connected destination without passing through other routers.
The routing table consists of the following key items:
■Destination address: Identifies the destination address or destination 
network of IP packets.
■Network mask: Identifies, together with the destination address, the address 
of the route segment where the destination host or router is located. For 
example, if the destination address is 129.102.8.10 and the network mask is 
255.255.0.0, the address of the route segment for the destination host or 
router is 129.102.0.0. The mask consists of several consecutive 1s and 0s, 
which can be expressed with dotted decimal system or with the number of 
consecutive 1s in the mask.
■Output interface: Indicates the interface of the router that forwards the IP 
packet.
■Next hop IP address: Indicates the next router to which the IP packet will be 
forwarded.
■The priority of this route added to IP routing table: Determines the best 
route. There may be different next hops to the same destination. These routes 
can be found by different routing protocols or they may be static routes 
configured manually. The route with higher priority (smaller value) is the best 
route. The user can configure multiple routes with different priorities to the 
same destination and select one to forward messages.
According to the destination of a route, it can be classified as:
■Sub-network route: The route whose destination is a sub-network
■Host route: The route whose destination is a host
According to the connection mode between the destination and the router, you 
can classify the router as:
■Direct route: The destination address and the router are located in the same 
segment.
■Indirect route: The destination address and the router are not located in the 
same segment.
To keep the routing table within a certain size, a default route is set. Whenever a 
data packet fails to find the routing table, the default route is selected to transfer 
the data packet.
In complicated networks, the digits assigned to a router in each network are its 
network address. For example, if router 8 (R8) is connected to three networks, it 
has 3 IP addresses and 3 physical ports. The routing table is shown in the figure 
below.