routerSendRedirectOfflink2 - TBD
routerSendRedirectOfflink2.seq [-tooloption ...] -p routerSendRedirectOfflink2.def
routerSendRedirectOfflink2 verify that NUT does not send a redirect message if NUT does not know the better router's link-local address.
TN NUT --------------------
==== echo-request to H3 ===> TN throws an echo-request to NUT mac src=TN mac dst=NUT ip src=TN's global ip dst=H3's global
<=== NS for R1 (if any) ==== src=NUT's link-local dst=R1's link-local target=R1's link-local w/ SLLA
==== NA for R1 (if any) ===> src=R1's link-local dst=NUT's link-local target=R1's link-local R=1, S=1, O=1 w/ TLLA
<=== echo-request to H3 ==== NUT forwards an echo-request to R1 mac src=NUT mac dst=R1 ip src=TN's global ip dst=H3's global
1. NUT must fowards an echo-request to the better router, R1:
2. NUT must not send a redirect message to TN. Because an ICMP target address field in a redirect message must contain a link-local address. But NUT does not know the better router's link-local address (see INITIALIZATION).
8.2. Router Specification
A router SHOULD send a redirect message, subject to rate limiting, whenever it forwards a packet that is not explicitly addressed to itself (i.e. a packet that is not source routed through the router) in which:
- the Source Address field of the packet identifies a neighbor, and
- the router determines that a better first-hop node resides on the same link as the sending node for the Destination Address of the packet being forwarded, and
- the Destination Address of the packet is not a multicast address, and
The transmitted redirect packet contains, consistent with the message format given in Section 4.5:
- In the Target Address field: the address to which subsequent packets for the destination SHOULD be sent. If the target is a router, that router's link-local address MUST be used. If the target is a host the target address field MUST be set to the same value as the Destination Address field.
- In the Destination Address field: the destination address of the invoking IP packet.
- In the options:
o Target Link-Layer Address option: link-layer address of the target, if known.
o Redirected Header: as much of the forwarded packet as can fit without the redirect packet exceeding 1280 octets in size.
A router MUST limit the rate at which Redirect messages are sent, in order to limit the bandwidth and processing costs incurred by the Redirect messages when the source does not correctly respond to the Redirects, or the source chooses to ignore unauthenticated Redirect messages. More details on the rate-limiting of ICMP error messages can be found in [ICMPv6].
perldoc V6evalTool perldoc V6evalRemote