31.4.9 IPv6 PIM-SM important reminder for use
Keep the following limitations in mind when configuring a network that uses IPv6 PIM-SM.
The Switch conforms to RFC 2362 (the PIM-SM specification), but differs from some parts of the RFC due to software functionality limitations. The following table describes the differences with the RFC.
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RFC |
Switch |
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|---|---|---|
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Packet format |
The RFC contains a field for setting a mask length for the encoding group address and encoding source address. |
The mask length of encoding addresses is fixed at 128. |
|
The RFC contains fields for setting the address family and encoding type for encoding group addresses and encoding source addresses. |
The address family for encoding addresses is fixed at 2 (IPv6), and the encoding type is fixed at 0 for the Switch. Connections cannot be established outside of IPv6 to PIM-SM. |
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|
The RFC contains a field for setting the PIM version of a PIM message header. |
The PIM version is fixed at 2. Connections to PIM version 1 cannot be established. |
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Join/Prune fragments |
Join/Prune messages can be fragmented even when they exceed the network MTU. |
If the size of a Join/Prune message to be sent is large, the Switch splits it into 8-KB parts before sending. Also, Join/Prune messages split before sending are sent by using IP fragments based on the network MTU length. |
|
Connections to PMBR |
The RFC contains a specification for connections to PMBRs (PIM Border Routers) and for (*, *, RP) entries. |
The Switch does not support connections to PMBR. Also, (*, *, RP) entries are not supported. |
|
Switching to shortest paths |
The RFC contains a switching method based on the data rate as an example of the timing for switching to the shortest path. |
When the Switch first receives data for the last-hop-router, it switches to the shortest path without checking the data rate. |
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Receiving C-RP-Adv and sending Bootstrap |
A Bootstrap message is permitted to be fragmented if the length of a generated message exceeds the maximum packet length. However, to suppress occurrences of fragmentation, the maximum number of rendezvous point candidates should be set. |
Only one BSR is allowed per system. In addition, the maximum number of group prefixes that can be set at the rendezvous point is 128. For the Switch, if the size of a Bootstrap message to be sent is large, it is IP-fragmented by MTU length and then sent. |
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Hello message option |
The HoldTime option (type 1) is defined in the RFC. |
In addition to the HoldTime option, the neighboring-router address list option (types 24 and 65001) is available. ( [31.4.3 See "Neighbor Detection".) |
|
Sending and receiving Join/Prune messaging |
(Send and receive S,G)RPT=1 Prune messages only. |
(Send and receive S,G)RPT=1 Join/Prune messaging. |