If you want to activate IP routing on the LAN profile, you have to enter the address and subnet mask commands on the Cisco 700. Also, you have to activate the
routing with the set ip routing on command. Example
shows a sample LAN profile configuration.
Potential Profile Pitfalls
Now we discuss issues of bridging and
routing with the different Cisco 700 profiles.
Different strategies are available
for bridging and routing with a Cisco 700 series router. Depending
on the strategy, sometimes problems happen. An example: If IP
routing is activated on the LAN profile and IP routing is not turned
on the standard profile, as shown in Figure ,
the IP traffic will pass from the standard profile to the bridge
engine (1), pass to the LAN profile (2), and come out on the
Ethernet interface/LAN profile (3). The difficulty arises with the
return-trip packets (4). The return traffic is routed from the LAN
profile to the IP Routing Engine (5). Having no access to the
standard profile, the return traffic gets caught and stops in the
routing engine. The following is a typical misconfiguration:
cd lan
set bridging on
set ip routing on
set ip address 10.1.1.1
cd internal
set bridging on
cd standard
set bridging on
The solution is to turn off routing
on the LAN interface and apply Layer 3 configuration to the internal
profile.
If the IP routing is activated
on the internal profile, as shown in Figure ,
the IP traffic will pass from standard profile to the bridge engine
(1), pass to the LAN profile (2), and pass to the Ethernet interface
LAN profile (3). The return traffic will then go from the Ethernet
segment to the LAN profile (4), go to the bridging engine (5), go to
the internal profile (6), go to the IP routing engine (7), go back
out to the internal profile (8), go toward the bridge engine (9),
and go to the bridge engine that sends the packet out to the
standard profile (10). The following is a typical proper
configuration when standard profile is involved:
cd lan
set bridging on
cd internal
set bridging on
set ip routing on
set ip address 10.1.1.1
cd standard
set bridging on
A similar solution can be
implemented when using a user profile, as shown in Figure .
If both IP routing and bridging are turned on for the Chicago
profile, all IP traffic flows to the IP routing engine (1). Not
shown in Figure
is that all other traffic (AppleTalk,
NetBEUI, and IPX/Sequenced Packet Exchange [SPX]) would flow to the
bridge engine. The IP traffic flows from the IP routing engine to
the internal profile (2) and then flows to the bridge engine (3).
All traffic, whether it is IP or nonrouted traffic like NetBEUI,
flows to the LAN profile (4), and flows on to the Ethernet segment
(5). The return trip traffic flows from
the Ethernet segment into the LAN profile (6), and then flows to the
bridge engine (7). The IP traffic flows to the internal profile (8),
and then flows to the routing engine (9), followed by the Chicago
profile (10). Traffic other than IP flows from the bridge engine to
the Chicago profile (not shown on Figure ).
The following is a typical correct configuration when a user profile
is involved:
cd lan
set bridging on
cd internal
set bridging on
set ip routing on
set ip address 10.1.1.1
cd standard
set bridging off
set user Chicago
set bridging off
set ip routing on
set ip address 192.168.1.1
If you change an IP address of a
profile, the IP routing is suspended, even if it still appears under
the same profile when performing the upload command. To
reactivate the IP routing process, you have to either reload
the router or type under the profile set ip routing on.
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