Method and tool for IP multicast network address translation (MNAT)
The present invention permits translation of SM addresses (*, G 1 ) and (*, G 2 ) to configurable SSM addresses (S 0 , G 0 ). IGMPv2 group membership queries from the receiver subnet are translated to IGMPv3 membership queries for processing in a SSM network. In the preferred embodiment, packets travel via a connection to the multicast router (mrouter). The mrouter queries an IGMPv2 receiver. The IGMPv2 receiver generates a membership report and sends it back to the mrouter. The mrouter translates the membership report into a (S 0 , G 0 ) as specified in a multicast address translation table and stores the translation in the Multicast Forward Information Base (MFIB) located in the mrouter. Multicast payload addressed (S 0 , G 0 ) flowing towards the IGMPv2 receiver can be translated to (S 0 , G 0 ). When media data is addressed to (S 0 , G 0 ), the mrouter consults the MFIB for forwarding and can also translate the destination address to (S 1 , G 1 ).
1. A method for translating SM (Standard Multicast) addresses to configurable SSM (Source Specific Multicast) addresses when an IGMPv2 receiver joins a multicasting group comprising the steps of:
(a) sending a query from a multicast router to an IGMPv2 receiver;
(b) generating a membership report with a SM address from the IGMPv2 receiver;
(c) transmitting the membership report with the SM address to the multicast router;
(d) translating the membership report with the SM address, (*, G 1 ), into an SSM address, (S 0 , G 0 ), as specified in a multicast address translation table through a management interface of the multicast router wherein the SM address is translated to the SSM address such that a group address (G 1 ) for a first group in the SM address is translated to a group address (G 0 ) for a second group different than the group address (G 1 ) for the first group and a source address (S 0 ) in the SSM address; and
(e) storing a translation of the (S 0 , G 0 ) address in a multicast forwarding information base in the multicast router.
2. The method of claim 1 further comprising the step of
consulting the multicast forwarding information base for forwarding when a payload is addressed (S 0 , G 0 ).
3. The method of claim 2 further comprising the step of:
translating the SSM address (S 0 , G 0 ) of the payload to a second SSM address (S 1 , G 1 ) wherein the group address of the second group and the source address of the SSM address are translated to the second SSM address with a source address of a source sending the payload and the group address of the first group.
4. The method of claim 2 further comprising the step of:
translating the address (S 0 , G 0 ) of the payload to address (S 0 , G 1 ).
5. A method for translating SM (Standard Multicast) addresses to configurable SSM (Source Specific Multicast) addresses when an IGMPv2 receiver joins a multicasting group comprising the steps of:
(a) generating a membership report with a SM address from an IGMPv2 receiver;
(b) transmitting the membership report with the SM address to a multicast router;
(c) translating the membership report with the SM address, (*, G 1 ), into an SSM address, (S 0 , G 0 ), as specified in a multicast address translation table through a management interface of the multicast router wherein the SM address is translated to the SSM address such that a group address (G 1 ) for a first group in the SM address is translated to a group address (G 0 ) for a second group different than the group address (G 1 ) for the first group and a source address (S 0 ) in the SSM address; and
(d) storing a translation of the (S 0 , G 0 ) address in a multicast forwarding information base in the multicast router.
6. The method of claim 5 further comprising
consulting the multicast forwarding information base for forwarding when a payload is addressed (S 0 , G 0 ).
7. The method of claim 6 further comprising
translating the address (S 0 , G 0 ) of the payload to address (S 1 , G 1 ).
8. The method of claim 6 further comprising
translating the address (S 0 , G 0 ) of the payload to address (S 0 , G 1 ).
9. A method for translating SM (Standard Multicast) addresses to configurable SSM (Source Specific Multicast) addresses when an IGMPv2 receiver joins a multicasting group comprising the steps of:
(a) sending a query from a multicast router to an IGMPv2 receiver;
(b) generating a membership report with a SM address from the IGMPv2 receiver;
(c) transmitting the membership report with the SM address to the multicast router;
(d) translating the membership report with the SM address, (*, G 1 ), into an SSM address, (S 0 , G 0 ), as specified in a multicast address translation table through a management interface of the multicast router wherein the SM address is translated to the SSM address such that a group address (G 1 ) for a first group in the SM address is translated to a group address (G 0 ) for a second group different than the group address (G 1 ) for the first group and a source address (S 0 ) in the SSM address;
(e) storing a translation of the (S 0 , G 0 ) address in a multicast forwarding information base in the multicast router;
(f) consulting the multicast forwarding information base for forwarding when a payload is addressed (S 0 , G 0 ); and
(g) translating the address (S 0 , G 0 ) of the payload to address (S 1 , G 1 ).