ERPS Sub-Ring not being formed between S5700 switches

Publication Date:  2016-06-30 Views:  775 Downloads:  0
Issue Description

The full sub-ring is not being formed in order to have one RPL in sub-ring. The major rings are woking the RPLs are configured for both rings.

In this scenario we assume we are aware of configuring the basic ERPS configuration.

The intersecting switch Nodes (LSW 3 - 4 - 5 - 6) , are configured in order to create Major rings and Sub-rings, see below configuration:


stp region-configuration

instance 1 vlan 1 to 4093

active region-configuration             

#

erps ring 1

control-vlan 4080

protected-instance 1

version v2

#

erps ring 2

control-vlan 4081

protected-instance 1

sub-ring

version v2



 See below network topology for further understanding.


Sub-ring is wanted to be formed between LSW 3 - 4 - 5 - 6, but from some cause is no being formed, the cause why is not being formed is because R-APS PDUs are not being exchanged between all the Sub-ring Nodes, this will result in not being able to set the RPL for the Sub-ring.

        -The R-APS PDUs sent by LSW3 can't reach LSW4, same behavior from LSW4 side.

        -The R-APS PDUs sent by LSW5 can't reach LSW6, same behavior from LSW6 side.

        -The R-APS PDUs can be exchanged on the Link between LSW3 <->LSW5,  same behavior for the Link between LSW4 <-> LSW6.


Siwtches LSW 3 - 4 - 5 - 6 are the intersecting Nodes of the rings, Major and Sub-ring rings, these we result in Common links: 

        -Major ring 1 and Sub-ring will have the common link between LSW3 - LSW4 (GE 0/0/2 - Ge0/0/2)

        -Major ring 2 and Sub-ring will have the common link between LSW5 - LSW6 (GE0/0/2 - GE0/0/2)

By default the Common links are appart from Major Rings.

Solution

By default the transmission of R-APS PDUs for a Sub-ring is in NVC (non virtual-channel).

          -in NVC the R-APS PDUs are not being injected in the Major Ring and the RPL of the Sub-ring can forward ERPS packets and data packets, because the Common links are appart of Major Rings obviously the Nodes of the Common Links can't forward the SUb-Ring ERPS packets.

          -this problem happens when the upper topology is encountered, more exacly when the Sub-ring has two common links with major rings.

In order to avoid this problem on all Nodes of the Sub-ring, under Sub-ring configuration we need to set the Transmission in VC(virtual-channel).

          -in VC the ERPS packets of the sub-ring are being forwarded by the Nodes, where both rings are configured, into Major rings, and in this mode the RPL of the Sub-ring will block the ERPS packets, see below  configuration:


 erps ring 2

control-vlan 4081

protected-instance 1

sub-ring

virtual-channel enable    

version v2


For the interfaces of the Nodes which are forming the Common Links need to have configuration for both ERPS ring (major and Sub-ring), se below confiuration:

  

interface GigabitEthernet0/0/2                                                            

description "Uplink Pijnacker"

port link-type trunk

port trunk allow-pass vlan 3400 3408 3450 3455 to 3456 3461 to 3462 3464 to 3465 3773 4080 4093

stp disable

erps ring 1

erps ring 2

END