ARP Table Broadcast MAC Address L2 Tunnel Communication
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Solution Overview
Problem
In communication systems, the connection of L3 and L2 tunnels is hindered when an IP address cannot be set for the L2 tunnel interface, preventing the intermediate router from resolving the destination MAC address and thus blocking IP packet transmission via the L2 tunnel.
Innovation Solution
A communication apparatus with a table storage unit that sets a broadcast MAC address as the destination MAC address in the ARP table, allowing the router to transmit IP packets via the L2 tunnel without assigning an IP address to the L2 tunnel interface, using the broadcast MAC address as a destination MAC address for IP packets received via the L3 tunnel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an IP address is set for the L2 tunnel interface in the intermediate router, then the router can acquire the destination MAC address by ARP and transmit IP packets via the L2 tunnel, but the service provider cannot provide the IP address in some cases
Solution Approach 1:
The invention changes the parameter used for MAC address resolution from a unicast IP address to a broadcast IP address. By setting the destination IP address to a broadcast address and using the corresponding broadcast MAC address in the ARP table, the router can resolve MAC addresses without requiring a specific unicast IP address to be assigned to the L2 tunnel interface, thus adapting to environments where IP addresses cannot be provided by the service provider.
2Ease of operation
If the intermediate router uses ARP to resolve the destination MAC address, then the MAC address can be acquired when IP addresses are set, but the router cannot resolve the destination MAC address when IP addresses are not set
Solution Approach 1:
The invention introduces a broadcast IP address as an intermediary in the MAC address resolution process. Instead of directly using the destination IP address of the IP packet for ARP resolution, the router uses a pre-configured broadcast IP address in the ARP table that maps to the broadcast MAC address. This intermediary approach allows the router to perform ARP resolution successfully even when no specific unicast IP address is assigned to the L2 tunnel interface.
3Adaptability or versatility
If the router transmits frames with broadcast MAC address via the L2 tunnel, then IP packet communication is enabled without L2 tunnel interface IP address, but additional configuration of ARP table with broadcast MAC address is required
Solution Approach 1:
The invention performs preliminary configuration by pre-setting the ARP table with a broadcast IP address mapped to the broadcast MAC address before IP packet transmission occurs. This preliminary action eliminates the need for complex runtime configuration or dynamic IP address assignment, as the broadcast MAC address mapping is already in place and can be used immediately for L2 tunnel communication without requiring an IP address on the L2 tunnel interface.
Data Source
AI summary
A communication apparatus which terminates an L2 tunnel and an L3 tunnel includes a table storage unit which stores an ARP table where a broadcast MAC address is set as a destination MAC address linked to a destination IP address, and a transmission unit which acquires the broadcast MAC address as a destination MAC address corresponding to a destination IP address of an IP packet received via the L3 tunnel by referring to the ARP table and transmits a frame to which the broadcast MAC address is added as a destination MAC address, via the L2 tunnel.