Designated Router
--> Designated Router is responsible for sending PIM Join/Register messages to RP when there are two or more routers are connected to LAN.
--> Uses PIM Hello messages to elect Designated Router on LAN.
--> The router with highest IP Address on LAN will be elected as Designated Router.
Designated Forwarder
--> Designated Forwarder is elected when there are multiple routers on LAN are receiving the same multicast traffic to forward it to the receiver.
--> Only Designated Forwarder will forward the multicast traffic to the receiver when there is duplicate multicast traffic on LAN.
--> Uses PIM Assert messages to elect Designated Forwarder on LAN.
--> The router with lowest IP Address on LAN will be elected as Designated Forwarder.
Md.Kareem
CCIE #54759
--> Designated Router is responsible for sending PIM Join/Register messages to RP when there are two or more routers are connected to LAN.
--> Uses PIM Hello messages to elect Designated Router on LAN.
--> The router with highest IP Address on LAN will be elected as Designated Router.
Designated Forwarder
--> Designated Forwarder is elected when there are multiple routers on LAN are receiving the same multicast traffic to forward it to the receiver.
--> Only Designated Forwarder will forward the multicast traffic to the receiver when there is duplicate multicast traffic on LAN.
--> Uses PIM Assert messages to elect Designated Forwarder on LAN.
--> The router with lowest IP Address on LAN will be elected as Designated Forwarder.
Md.Kareem
CCIE #54759
RFC 7761 says highest IP address wins PIM Assert mechanism:
ReplyDelete4.6.3. Assert Metrics
Assert metrics are defined as:
struct assert_metric {
rpt_bit_flag;
metric_preference;
route_metric;
ip_address;
};
When comparing assert_metrics, the rpt_bit_flag, metric_preference,
and route_metric fields are compared in order, where the first lower
value wins. If all fields are equal, the primary IP address of the
router that sourced the Assert message is used as a tie-breaker, with
the highest IP address winning.