Nokia T66280, M1122 user manual Routing, Bridging, Network Address Port Translation

M1122 User Manual

DRFC2364 Virtual circuit multiplexed PPP over AAL5 (PPP-VC)

DRFC2364 Virtual circuit multiplexed PPP over AAL5 used to tunnel LAN/VBRIDGE PPTP packets (TUNNELED-PPP-VC)

If an IP address is given to a virtual channel interface and bridging is enabled at that interface, then IP data at that interface is routed and all other protocols are bridged. The only encapsulation which allows both bridging and routing simultaneously is ETH-LLC. For example, it is possible to route ETH-LLC encapsulated packets and at the same time bridge, for example, PPPoE packets (PPPoE packets are transported directly over Ethernet frame, not within IP packets).

4.2Routing

Routing is based on routing entries in a routing table. Static routes are added via the management interface and dynamic routing is done using RIP and RIPv2. Routing is done between the Ethernet 10Base-T interface and the virtual channel connection (VCC) of the ATM/ADSL interface. M1122 supports up to 8 simultaneous VCCs.

M1122 supports IGMP (Internet Group Management Protocol) proxy receive function for IP multicast applications.

4.3Bridging

Bridging is supported to provide full protocol transparency. Bridging can be used simultaneously with IP routing. M1122 works as a self-learning bridge supporting up to 1024 MAC addresses. Bridging is done between the Ethernet 10Base-T interface and each ATM VCC interface. Optionally, the bridging between the VCCs can be disabled.

4.4Network Address Port Translation

M1122 supports Network Address Port Translation (NAPT) for TCP/IP, UDP/IP and ICMP/IP protocols. When NAPT is used, a single IP address is allocated to a VCC which leads to the public IP network. The Ethernet subnet has private IP addressing and is not visible to the VCC. NAPT translates the IP source address and source port number dynamically to the VCC IP address and port number. Similarly, packets coming from the VCC are mapped back to the original destination addresses. NAPT allows up to hundreds of hosts to share a

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