3com S7906E 설치 설명서

 

1-7 

node RRPP ring group and an assistant-edge node RRPP ring group configured, only one subring 

sends and receives Edge-Hello packets, thus reducing CPU workload.  

As shown in

  Figure 1-5

, Device B is the edge node of Ring 2 and Ring 3, and Device C is the 

assistant-edge node of Ring 2 and Ring 3. Device B and Device C need to send or receive Edge-Hello 

packets frequently. If more subrings are configured or load balancing is configured for more multiple 

domains, Device B and Device C will send or receive a mass of Edge-Hello packets.  

To reduce Edge-Hello traffic, you can assign Ring 2 and Ring 3 to an RRPP ring group configured on the 

edge node Device B, and assign Ring 2 and Ring 3 to an RRPP ring group configured on Device C. 

After such configurations, if all rings are activated, only Ring 2 on Device B sends Edge-Hello packets.  

Ideally, an RRPP ring can fast converge because the transit nodes on it can detect link failures fast and 

send out notifications immediately. In practice, however, some devices on an RRPP ring may not 

support RRPP and thus RRPP can detect link failures between these devices only through the timeout 

mechanism. This results in long-time traffic interruption and failure to implement millisecond-level 

convergence.  

To address this problem, a fast detection mechanism was introduced. The mechanism works as follows: 

z 

The master node sends Fast-Hello packets out its primary port at the interval specified by the 

Fast-Hello timer. If the secondary port receives the Fast-Hello packets sent by the local master 

node before the Fast-Fail timer expires, the entire ring is in Health state; otherwise, the ring transits 

into Disconnect state.  

z 

The edge node sends Fast-Edge-Hello packets out its common ports at the interval specified by 

the timer resolution. If the assistant-edge node fails to receive the Fast-Edge-Hello packets within 

three times the timer resolution, the SRPTs transit to Disconnect state.  

As shown in 

, with fast detection enabled for RRPP domain 1, Device A, the master node of 

Ring 1, sends out Fast-Hello packets periodically and determines the ring status according to whether 

Fast-Hello packets are received before the Fast-Fail timer expires, thus implementing link status fast 

detection.  

 

z 

The timer resolution refers to the shortest-period timer provided on an RRPP node.  

z 

To implement fast detection on an RRPP ring, enable fast detection on the master node, edge 

node, and assistant-edge node of the RRPP ring.  

 

Here are several typical networking applications. 

As shown in 

, there is only a single ring in the network topology. In this case, you only need to 

define an RRPP domain.