Alcatel-Lucent OmniAccess 700, Руководство по настройке CLI

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Integrated Routing and Bridging
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Chapter name (automatic)
200
Beta Beta
CLI Configuration Guide
Alcatel-Lucent
I
NTEGRATED
R
OUTING AND
B
RIDGING
O
VERVIEW
When there is a requirement to bridge local traffic within several segments while
having hosts on the bridged segments, to reach the hosts or routers on routed
networks, IRB is configured on the system.
Using this feature, local or unroutable traffic is bridged among bridge interfaces
and routable traffic is routed to other routed interfaces.
IRB allows the user to both route and bridge a protocol in the same router with
connectivity between all the interfaces.
A
LCATEL
-L
UCENT
S
PECIFIC
IRB O
VERVIEW
The L2-GE card on the OA-700 system is a VLAN-aware Ethernet switch.
However, for routing across VLANs or between traffic on the L2-GE card and
other cards such as the T1 or an E1 card, there has to be a mechanism to detect
traffic that is to be routed, and subject it to normal IP packet processing activities
such as filters, NAT, IPsec, FIB lookup, etc. Hence a L2-GE port will then be
capable of taking part in both bridging and routing at the same time. This
technology is called IRB on the OA-700
.
If the physical ports belonging to a VLAN are thought of as defining a logical
bridge/switch, then the mechanism of sending an incoming packet from this
bridge to the logical router inside the OA-700 is to connect the bridge and the
router by a logical VLAN interface. This interface forms a logical pipe between the
bridge and the router inside the system. So, the router inside sees the packet as
coming in on a VLAN interface, which behaves like other interfaces such as
Ethernet, Serial, etc., from the point of view of IP services.
Once the packet has undergone the ingress policies configured on the VLAN
interfaces, as well as a FIB lookup, an egress interface is found and the packet is
acted on by the policies configured on this egress interface. If it turns out that the
egress interface is a physical interface such as Ethernet or T1 or an E1 or even a
sub-interface on a physical interface (e.g., a Frame Relay sub-interface), then
everything proceeds as usual. If the egress interface is a logical VLAN interface,
then it will be sent out of the appropriate physical interface port(s) that belong to
the VLAN.