Zyxel IES-1248 EE Инструкция по эксплуатации онлайн [262/544] 154557

Zyxel IES-1248 EE Инструкция по эксплуатации онлайн [262/544] 154557
Chapter 39 IP Bridge
IES-1248-51/51A/53 User’s Guide
262
VLANs in IP bridges are exclusive. They can be in at most one domain. In addition, VLANs in
IP bridges share the same VLAN space as regular VLANs, so VLANs in IP bridges must have
different VLAN IDs than regular VLANs.
39.1.2.1.1 Configuring VLANs for Domains
To add a VLAN to a domain,
1 Add (Join) a new (undefined) VLAN ID to the domain.
2 Create the VLAN in the system using the regular screens or commands for VLANs.
To remove a VLAN from a domain,
1 Delete the VLAN from the system using the regular screens or commands for VLANs.
2 Remove (Leave) the VLAN ID from the domain.
39.1.2.2 Edge Routers
Edge routers are usually the gateways that are provided to the subscribers. They can also be
gateways that are specified in static routing table entries. Each edge router, in addition to its IP
address, has an associated VLAN ID. When the IES-1248 forwards a frame to an edge router,
it uses this VLAN ID to replace whatever VLAN ID the subscriber specified. The IES-1248
also uses the VLAN ID to identify the domain the edge router is in.
If two edge routers are in different domains, it is possible for them to have the same IP
address.
39.1.2.3 Downlink Interfaces
Downlink interfaces provide forwarding information for downstream traffic. The IES-1248
learns some of this information by snooping DHCP packets. For static IP addresses, you
should provide this information manually. In this case, specify the VLAN ID and, optionally,
the PVC for a range of IP addresses. The IES-1248 uses the VLAN ID to identify the domain
the downlink interface is in. Downlink interfaces in the same domain cannot have overlapping
IP addresses.
Since the IES-1248 creates downlink interfaces by snooping DHCP packet, if subscribers are
on a different VLAN in a domain, make sure the DHCP server assigns a different range of IP
addresses to these subscribers, whether or not the DHCP VLAN feature is enabled in the
domain. The DHCP server can use the DHCP option 82 feature to distinguish between users
and assign different IP addresses appropriately.
The DHCP server cannot assign the same or an overlapping range of IP addresses to
subscribers on a different VLAN in the same domain because downlink interfaces in the same
domain cannot have overlapping IP addresses.
39.1.2.4 Routing Tables
Each domain has its own routing table. Each routing table contains entries that, based on the
destination IP address, control where the IES-1248 forwards packets (for upstream and
downstream traffic). The IES-1248 automatically creates routing table entries for each
downlink interface and for each edge router in the domain. You can create additional entries
by specifying the edge router to which the IES-1248 should forward traffic for a particular
destination IP address or IP subnet.

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