FAQ-Why Does the IS-IS Neighbor Relationship Fail to Be Established on the DSLAM

Publication Date:  2015-05-05 Views:  155 Downloads:  0
Issue Description
Why Does the IS-IS Neighbor Relationship Fail to Be Established on the DSLAM?
Solution
Figure 1 shows the actual networking.

Figure 1 Networking



IS-IS transmits BPDU packets whose MAC address is in 0180-C2##-####-#### format. BPDU packets are reserved multicast packets at the link layer and need to carry VLAN tags when transparently transmitted by the DSLAM. IS-IS Hello packets do not carry VLAN tags when being transmitted through Layer 3 GE interfaces; therefore, the DSLAM fails to transparently transmit IS-IS Hello packets. The PON interface receives no IS-IS Hello packet from the peer end, so the PON interface fails to establish the neighbor relationship.

To address this problem, configure the GE interface as a subinterface which allows packets to carry VLAN tags so that the DSLAM can transparently transmit these packets.

NOTE:
The DSLAM adds VLAN tags to packets sent by a PON interface.

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