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Metro1000 Ethernet Services Bridge
VBs and LPs
Figure 1 Relationship between VBs, LPs, external ports, and VCTRUNK ports
Metro1000 Transparent and Virtual Bridges
- The services of multiple Transparent Bridges are isolated from each other, but there is no isolation of services within the same Transparent Bridge, and the entire Transparent Bridge is a switching domain.
- The services of multiple virtual bridges are isolated from each other, and the services of different VLAN IDs within the same virtual bridge are also isolated from each other, and the switching domain of the whole virtual bridge is divided into multiple sub-switching domains according to different VLAN IDs.
Description: Figure 2 Transparent and Virtual Bridges Virtual Bridge
Table 1 Transparent and Virtual Bridges
| Item | Transparent bridge | Virtual bridge |
|---|---|---|
| VLAN filtering table | Not configured | Must be configured |
| Ingress Filtering | No legal checking of VLAN tags, all data frames entering the bridge are legal data frames. | Legitimate checksums are performed on the contents of VLAN tags. If the VLAN ID is not the VLAN ID defined in the VLAN filter table for that port, the data frame is discarded. |
| MAC Address Learning Mode | SVL | IVL |
| Data frame forwarding mode | Query the MAC address table according to the destination MAC address of the data frame to get the forwarding port of the data frame. | Query the MAC address table according to the destination MAC address and VLAN ID of the data frame to get the forwarding port of the data frame. |
| Broadcast Scope | Forward broadcast data frames on all ports of the bridge. | Forward broadcast data frames in the forwarding ports defined in the VLAN filtering table. |
Description:- When the bridge adopts SVL learning mode, it builds a table entry of the MAC address table based on the source MAC address of a data frame with the source port of that data frame, which is valid for all VLANs.
- When the bridge adopts the IVL learning mode, the table entry of the MAC address table is created with the source port of a data frame based on the source MAC address of the data frame and the VLAN ID carried by the data frame, and the table entry is valid only for that VLAN.
Table 2 Bridge Types Supported by Ethernet Single Boards
| Bridge Type | Bridge switching mode | Bridge learning mode | Ingress filtering | |
|---|---|---|---|---|
|
IEEE 802.1d MAC bridge |
SVL/Entry Filtering not enabled | SVL | Not enabled | |
|
IEEE 802.1q Virtual Bridge |
IVL/Entry Filtering Enable | IVL | IEEE 802.1q Virtual Bridge IVL/Entry Filtering Enable | |
|
IEEE 802.1ad Provider Bridge |
1 | SVL/Entry Filtering not enabled | SVL | Not enabled |
| 2 | IVL/inlet filtering enabled | IVL | Enable | |
- IEEE 802.1d MAC bridge: data frames entering the bridge are not checked for VLAN tag content, and Layer 2 switching is performed based on the destination MAC address of the data frame.
- IEEE 802.1q Virtual Bridge: supports one layer of VLAN-tagged data isolation. Data frames entering the bridge are checked for VLAN tag content, and Layer 2 exchanges are performed based on the destination MAC address and the VLAN ID carried by the data frame.
- Data frames entering the bridge are not checked for VLAN tag content and are exchanged at Layer 2 based on the destination MAC address of the data frame.
- Data frames entering the bridge are checked for VLAN tag content, and Layer 2 exchanges are performed based on the destination MAC address and the S-VLAN ID carried by the data frame.
Description:- A routing table entry is automatically deleted after it has not been updated for a certain period of time (i.e., no new data frames have been received from that MAC address to cause that MAC address to be re-learned). This mechanism is called aging, and this period of time is called the aging time. the aging time for the MAC address table is 5 minutes by default, and you can set this value through the network administrator.
- There is a limit to the number of MAC addresses that can be learned.
A bridge is a functional unit that enables the interconnection of two or more LANs.
VB (Various Bridge) means Various Bridge. For an Ethernet board with Layer 2 switching capability, its switching domain can be divided into multiple independent sub-switching domains, so that different VBs cannot access each other without service connectivity. Each VB has an independent configuration mode and uses VLANs independently, and the VLANs of different VBs can be the same.
LP (Logic Port) is a logical port, a VB contains a number of LPs. by configuring the hooking relationship, we can hook multiple external ports and VCTRUNK ports to the same VB.
The relationship between VBs, LPs, external ports, and VCTRUNK ports is shown in Figure 1.
As shown in Figure 2, the same logical port can belong to one or more sub-switching domains with different VLAN IDs. under the network management configuration interface, that is, the same logical port can belong to the filter table with different VLAN IDs.
The basis for forwarding Layer 2 switching services is the learning of MAC addresses. The learning modes of the bridge are categorized into SVL (Shard VLAN Learning) and IVL (Independence VLAN learning).
As shown in Table 2, the types of bridges currently supported by Ethernet veneers are categorized as follows.
-
IEEE 802.1ad Provider Bridge: Supports two-layer VLAN-tagged data frames, uses the outer S-VLAN for VLAN isolation, and supports only ports with hooked port attributes of C-Aware and S-Aware. The bridge supports the following two switching modes.
The table entries of the MAC address table reflect the correspondence between MAC addresses and ports, and its table entries are categorized into:
-
Dynamic table entries
Table entries acquired by the bridge using SVL/IVL learning mode. Dynamic table entries are aged and are lost after the Ethernet switching board is reset.
-
Static table entries
Table entries corresponding to MAC addresses and ports that are manually added to the MAC address table by the network administrator through network management, i.e., unicast table entries. Static table entries are not aged and are not lost after an Ethernet switching board reset.
-
Blacklist
A table entry used to discard data frames containing a specific destination MAC address, i.e., a MAC disable table entry. Blacklists are configured by the network administrator. The table entries are not aged and are not lost after an Ethernet switching board reset.
For aggregation services, it is often desirable for non-central and central sites to be able to access each other, but not for non-central sites to access each other. In this case, it is necessary to define the ports on which the bridge is hooked up as Hub ports or Spoke ports.
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Hub Port
Hub ports can access each other with Hub ports, and Hub ports can access each other with Spoke ports.
-
Spoke Port
Spoke ports and Spoke ports cannot access each other, and Hub ports and Spoke ports can access each other.
The hookup port defaults to the Hub port.
