Analyzed the logs and found that the customer was trying to configure Port#10 of the access switch to be used for voice and data by using ADAC with LLDP Detection. Found some mis-configurations in the switch as 'med-network-policies' were not disabled by the customer on the port in question. After disabling the 'med-network-policies' the IP Phone started getting IP from the DHCP Server, but PCs were not getting IPs. Provided the complete configuration to the customer which is given below:
It is important to enable ADAC both on the interface as well globally. Please find below the steps to configure ADAC using LLDP detection which is used to support both voice and data to support Auto-Configuration with Avaya’s stackable Ethernet Routing switches and IP Phone sets. ADAC LLDP-MED detection will be enabled detect the IP Phone and apply QoS as follows:
Step1: Enable ADAC Globally
(a) ERS 4000 only if using release 5.5 or higher:
ERS-Stackable(config)#interterface fastEthernet <Ports>
ERS-Stackable(config-if)#no lldp med-network-policies
ERS-Stackable(config-if)#exit
(b) Enable ADAC using VLAN 6, set the operation mode to tagged-frames, and add the uplink port:
ERS-Stackable(config)#adac voice-vlan 6
ERS-Stackable(config)#adac op-mode tagged-frames
ERS-Stackable(config)#adac uplink-port 2
ERS-Stackable(config)#adac traps enable
ERS-Stackable(config)#adac enable
Step2: Enable ADAC at interface level
(a) Enable ADAC on required ports, set the ADAC detection to LLDP only, and enable the ADAC tag mode to tagged frames and untag the default VLAN:
ERS-Stackable(config)#interface fastEthernet <Ports>
ERS-Stackable(config-if)#adac detection lldp
ERS-Stackable(config-if)#no adac detection mac
ERS-Stackable(config-if)#adac tagged-frames-tagging untag-pvid-only
ERS-Stackable(config-if)#adac enable
ERS-Stackable(config-if)#exit
Step3: Enable LLDP Vendor Specific settings:
(a) Add LLDP Vendor Specific options:
ERS-Stackable(config)#lldp vendor-specific avaya call-server 1 <IP Address>
ERS-Stackable(config)#lldp vendor-specific avaya file-server 1 <IP Address>
ERS-Stackable(config)#interface fastEthernet <Ports>
ERS-Stackable(config)#lldp vendor-specific avaya dot1q-framing tagged
ERS-Stackable(config)#exit
Information regarding Med-Network-Policy default values: The default values for this policy is “application type = voice”, “tagging = untagged”, “DSCP = 46”, “VLAN priority = 6”, and “VLAN id= 0”. If ADAC is configured and an IP Phone is detected, the dynamic LLDP MED policy with the ADAC Voice VLAN ID will never be installed, resulting in the IP phone not receiving the VLAN configuration for the case when ADAC tagged frames is used. The reason being, the phone will not use the correct VLAN (i.e. VLAN#6 in our case) and will use the default VLAN (VLAN#0).
Later, customer requested more information regarding some protocols and technologies which are as follows:
1) SMLT v/s SLT
SMLT stands for Split MultiLink Trunking which is a standard Layer-2 design using MLT-based connections. SMLT works over MLT and the links between the two switches could be scaled upto a maximum of 8 in order to provide link redundancy. Since, SMLTs works over MLTs, the number of SMLTs that you could deploy on a switch is equal to the number of permissible MLTs.
SLT stands for Single Link Trunking which is a standard Layer-2 design setup which is imposed using port-based connections. The only difference between SMLT and SLT is lies in the scalability of links in SMLT to provide redundancy apart from some configuration differences. Since SLTs are based port-based, the number of SLTs that you can deploy is equal to the number of ports in the switch.
2) Information regarding various parameters:
VLACP: Virtual LACP (VLACP) is a lightweight protocol that is used to detect end-to-end failure by propogating th link status that are connected point-to-point. This protocol is based on LACP but does not perform any kind of link porpogation, it just serves the purpose of eliminating the end-to-end link failure by sending and recieving the VLACP PDUs. It is a good practice to enable VLACP on all the uplink and IST ports. Further configuration paramters such as time out value and others you can find on Page#31 of the attached document.
SLPP: Simple Loop Protection Protocol is a proprietry loop protection protocol designed to detect loops (especially over triangle topologies where a core cluster is connected to an edge device). It detects loop by sending SLPP BPDUs over the SMLT while keeping a counter of these BPDUs if they are recieved at the other end. If a certain preconfigured thershold is exceeded SLPP brings down one SMLT port which ends the loop sacrificing the redundancy to the core. Please be aware that, it is configured only on SMLT/SLT ports and not on the IST ports. You can find further details and configuration paramters you can on Page#33 of the attached document.
BPDU Filtering: As the name suggests, it is used to block unwanted root selection and flooding of BPDUs from unkown deviecs. It is enabled on all the accesws ports of the edge device. For further information you can refer Page#27 of the attached document.
3) Information regarding loop-detection and system logging:
Regarding loop detection: The most alarming factor which points towards a potential loop in the network is sustained High CPU Utilization even leading to the crash of the switch as generally a loop results in a huge broadcast storm due to exponential replication of packets. Various protocols such as STP and SLPP which used specific PDUs are used to check loops in the the live network. There are other features such as 'Port-Limit' at the edge and 'CP Limit' and 'Extended CP limit' at the core switch to check these multicast/broadcast storms, which blocks the port in question when the configured therhold is exceeded.
Logging in ERS Edge and Core switches are enabled by default and could be seen in the ouput of 'Show Tech'. You can even use specific commands such as 'Show Log File Tail' on ERS8600 to see the system logging.
