HP 5500 Ei 5500 Si Switch Series Configuration Guide
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81
Step Command Remarks
1. Enter system view.
system-view N/A
2. Configure the priority of
the current device.
• In STP/RSTP mode:
stp priority priority
• In PVST mode:
stp vlan vlan-list priority priority
• In MSTP mode:
stp [ instance instance-id ] priority priority Use one of the commands.
The default setting is
32768.
Configuring the maximum hops of an MST region
By setting the maximum hops of an MST region, you can restrict the region size. The maximum hops...](http://img.usermanuals.tech/thumb/36/58909/w64_hp-5500-ei-5500-si-switch-series-configuration-guide-291.png "Page 292
81
Step Command Remarks
1. Enter system view.
system-view N/A
2. Configure the priority of
the current device.
• In STP/RSTP mode:
stp priority priority
• In PVST mode:
stp vlan vlan-list priority priority
• In MSTP mode:
stp [ instance instance-id ] priority priority Use one of the commands.
The default setting is
32768.
Configuring the maximum hops of an MST region
By setting the maximum hops of an MST region, you can restrict the region size. The maximum hops...")
80 • You can configure the current device as the root bridge by setting the device priority to 0. For the device priority configuration, see Configuring the device priority. Configuring the current device as the root bridge of a specific spanning tree To configure the current device as the root bridge of a specific spanning tree: Step Command Remarks 1. Enter system view. system-view N/A 2. Configure the current device as the root bridge. • In STP/RSTP mode: stp root primary • In PVST mode: stp vlan vlan-list root primary • In MSTP mode: stp [ instance instance-id ] root primary Use one of the commands. By default, a device does not function as the root bridge. Configuring the current device as a secondary root bridge of a specific spanning tree To configure the current device as a secondary root bridge of a specific spanning tree: Step Command Remarks 1. Enter system view. system-view N/A 2. Configure the current device as a secondary root bridge. • In STP/RSTP mode: stp root secondary • In PVST mode: stp vlan vlan-list root secondary • In MSTP mode: stp [ instance instance-id ] root secondary Use one of the commands. By default, a device does not function as a secondary root bridge. Configuring the device priority CAUTION: • Yo u c a n n o t c h a n g e t h e p r i o r i t y o f a d e v i c e a f t e r i t i s c o n f i g u re d a s t h e ro o t b r i d g e o r a s a s e c o n d a r y ro o t bridge. • During root bridge selection, if all devices in a spanning tree have the same priority, the one with the lowest MAC address will be selected as the root bridge of the spanning tree. Device priority is a factor in spanning tree calculation. The priority of a device determines whether the device can be elected as the root bridge of a spanning tree. A lower numeric value indicates a higher priority. You can set the priority of a device to a low value to specify the device as the root bridge of the spanning tree. A spanning tree device can have different priorities in different MSTIs. To configure the priority of a device in a specified MSTI:
81 Step Command Remarks 1. Enter system view. system-view N/A 2. Configure the priority of the current device. • In STP/RSTP mode: stp priority priority • In PVST mode: stp vlan vlan-list priority priority • In MSTP mode: stp [ instance instance-id ] priority priority Use one of the commands. The default setting is 32768. Configuring the maximum hops of an MST region By setting the maximum hops of an MST region, you can restrict the region size. The maximum hops configured on the regional root bridge will be used as the maximum hops of the MST region. Configuration BPDUs sent by the regional root bridge always have a hop count set to the maximum value. When a device receives this configuration BPDU, it decrements the hop count by 1, and uses the new hop count in the BPDUs that it propagates. When the hop count of a BPDU reaches 0, it is discarded by the device that received it. This prevents devices beyond the reach of the maximum hop from participate in spanning tree calculation, so the size of the MST region is limited. Make this configuration on the root bridge only. All other devices in the MST region use the maximum hop value set for the root bridge. To configure the maximum number of hops of an MST region: Step Command Remarks 1. Enter system view. system-view N/A 2. Configure the maximum hops of the MST region. stp max-hops hops 20 by default. Configuring the network diameter of a switched network Any two terminal devices in a switched network ar e connected through a specific path composed of a series of devices. The network diameter is the number of devices on the path composed of the most devices. The network diameter is a parameter that indicates the network size. A bigger network diameter indicates a larger network size. Based on the network diameter you configured, the system automatically sets an optimal hello time, forward delay, and max age for the device. To configure the network diameter of a switched network: Step Command Remarks 1. Enter system view. system-view N/A
82
Step Command Remarks
2. Configure the network
diameter of the switched
network. • In STP/RSTP/MSTP mode:
stp bridge-diameter diameter
• In PVST mode:
stp vlan vlan-list bridge-diameter diameter Use one of the
commands.
The default setting is 7.
NOTE:
• In STP/RSTP/MSTP mode, each MST region is considered as a device and the configured network
diameter is effective only for the CIST (or the common root bridge), but not for MSTIs.
• In PVST mode, the network diameter configurat ion is effective on the root bridge only.
Configuring spanning tree timers
The following timers are used for spanning tree calculation:
• Forward delay
It is the delay time for port state transition. To prevent temporary loops on a network, the spanning
tree sets an intermediate port state, the learning st ate, before it transitions from the discarding state
to the forwarding state, and requires that the port transitions its state afte r a forward delay timer to
make sure that the state transition of the lo cal port keeps synchronized with the peer.
• Hello time
The device detects whether a link failure has occu rred with the hello time interval. The spanning
tree sends a configuration BPDU every hello time in terval. If the device receives no configuration
BPDUs within the hello time interval, it recalculates the spanning tree.
• Max age
In the CIST of an MSTP network or each VLAN of a PVST network, the device uses the max age
parameter to determine whether a configuration BPDU received by a port has expired. If a port
receives a configuration BPDU that has expired, that MSTI must be re-calculated. The max age
timer is ineffective for MSTIs.
To avoid frequent network changes, be sure that the settings of the hello time, forward delay and
max age timers meet the following formulas:
{ 2 × (forward delay – 1 second) ƒ max age
{ Max age ƒ 2 × (hello time + 1 second)
HP does not recommend you to manually set the spanning tree timers. Instead, you can specify the
network diameter and let spanning tree protocols automatically calculate the timers based on the
network diameter. If the network diameter uses the defa ult value, the timers also use their default values.
Configure the timers on the root bridge only, and the ti mer settings on the root bridge apply to all devices
on the entire switched network.
Configuration restrictions and guidelines
• The length of the forward delay timer is related to the network diameter of the switched network. The
larger the network diameter is, the longer the fo rward delay time should be. If the forward delay
timer is too short, temporary redundant paths migh t occur. If the forward delay timer is too long,
network convergence might take a long time. HP recommends you to use the default setting.
83 • An appropriate hello time setting enables the device to quickly detect link failures on the network without using excessive network resources. If the hello time is too long, the device will mistake packet loss as a link failure and trigger a new spanni ng tree calculation process. If the hello time is too short, the device will frequently send the same configuration BPDUs, which adds the device burden and wastes network resources. HP recommends you to use the default setting. • If the max age timer is too short, the device wi ll frequently begin spanning tree calculation and might mistake network congestion as a link failure. If the max age timer is too long, the device might fail to quickly detect link failures and begin s panning tree calculations, reducing the auto-sensing capability of the network. HP recommends you to use the default setting. Configuration procedure To configure the spanning tree timers: Step Command Remarks 1. Enter system view. system-view N/A 2. Configure the forward delay timer. • In STP/RSTP/MSTP mode: stp timer forward-delay time • In PVST mode: stp vlan vlan-list timer forward-delay time Optional. Use one of the commands. The default setting is 15 seconds. 3. Configure the hello timer. • In STP/RSTP/MSTP mode: stp timer hello time • In PVST mode: stp vlan vlan-list timer hello time Optional. Use one of the commands. The default setting is 2 seconds. 4. Configure the max age timer. • In STP/RSTP/MSTP mode: stp timer max-age time • In PVST mode: stp vlan vlan-list timer max-age time Optional. Use one of the commands. The default setting is 20 seconds. Configuring the timeout factor The timeout factor is a parameter used to decide the timeout time, in the following formula: Timeout time = timeout factor × 3 × hello time. After the network topology is stabilized, each non-root-bridge device forwards configuration BPDUs to the downstream devices at the interval of hello time to determine whether any link is faulty. If a device does not receive a BPDU from the upstream device within nine times the hello time, it assumes that the upstream device has failed and starts a new spanning tree calculation process. Sometimes a device might fail to receive a BPDU from the upstream device because the upstream device is busy. If a spanning tree calculation occurs, the calculation can fail and also waste network resources. In a stable network, you can prevent undesired spanning tree calculations by setting the timeout factor to 5, 6, or 7. To configure the timeout factor: Step Command Remarks 1. Enter system view. system-view N/A
84 Step Command Remarks 2. Configure the timeout factor of the device. stp timer-factor factor 3 by default. Configuring the maximum port rate Th e m a xi mu m ra t e o f a p o r t re fe r s t o t h e m a xi m u m nu m b e r o f B PD Us t h e p o r t c a n s e n d wi t h i n e a ch h e l l o time. The maximum rate of a port is related to the ph ysical status of the port and the network structure. The higher the maximum port rate is, the more BPDUs will be sent within each hello time, and the more system resources will be used. By setting an approp riate maximum port rate, you can limit the rate at which the port sends BPDUs and prevent spanning tr ee protocols from using excessive network resources when the network becomes unstable. HP recommends you to use the default setting. To configure the maximum rate of a port or a group of ports: Step Command Remarks 1. Enter system view. system-view N/A 2. Enter interface view or port group view. • Enter Layer 2 Ethernet interface view or Layer 2 aggregate interface view: interface interface-type interface-number • Enter port group view: port-group manual port-group-name Use one of the commands. 3. Configure the maximum rate of the ports. stp transmit-limit limit 10 by default. Configuring edge ports If a port directly connects to a user terminal rather than another device or a shared LAN segment, this port is regarded as an edge port. When network to pology change occurs, an edge port will not cause a temporary loop. Because a device does not determ ine whether a port is directly connected to a terminal, you must manually configure the port as an edge port. After that, the port can transition rapidly from the blocked state to the forwarding state. Configuration restrictions and guidelines • If BPDU guard is disabled, a port set as an edge port will become a non-edge port again if it receives a BPDU from another port. To restore the edge port, re-enable it. • If a port directly connects to a user terminal, configure it as an edge port and enable BPDU guard for it. This enables the port to transition to th e forwarding state quickly while ensuring network security. • You cannot configure edge port settings and loop guard on a port at the same time. Configuration procedure To specify a port or a group of ports as edge port or ports:
85 Step Command Remarks 1. Enter system view. system-view N/A 2. Enter interface view or port group view. • Enter Layer 2 Ethernet interface view or Layer 2 aggregate interface view: interface interface-type interface-number • Enter port group view: port-group manual port-group-name Use one of the commands. 3. Configure the current ports as edge ports. stp edged-port enable All ports are non-edge ports by default. Configuring path costs of ports Path cost is a parameter related to the rate of a port . On a spanning tree device, a port can have different path costs in different MSTIs. Setting appropriate pat h costs allows VLAN traffic flows to be forwarded along different physical links, achieving VLAN-based load balancing. You can have the device automatically calculate the default path cost, or you can configure the path cost for ports. Specifying a standard for the device to use when it calculates the default path cost CAUTION: If you change the standard that the device uses to calculate the default path costs, you restore the path costs to the default. You can specify a standard for the device to use in automatic calculation for the default path cost. The device supports the following standards: • dot1d-1998 —The device calculates the default path cost for ports based on IEEE 802.1d-1998. • dot1t —The device calculates the default path cost for ports based on IEEE 802.1t. • legacy —The device calculates the default path cost for ports based on a private standard. Tabl e 14 sho ws the mappings between the link speed and the path cost. Table 14 Mappings between the link speed and the path cost Link speed Port type Path cost IEEE 802.1d-1998 IEEE 802.1t Private standard 0 N/A 65535 200,000,000 200,000 10 Mbps Single port 100 2,000,000 2000 Aggregate interface containing 2 Selected ports 1,000,000 1800 Aggregate interface containing 3 Selected ports 666,666 1600
86 Link speed Port type Path cost IEEE 802.1d-1998 IEEE 802.1t Private standard Aggregate interface containing 4 Selected ports 500,000 1400 100 Mbps Single port 19 200,000 200 Aggregate interface containing 2 Selected ports 100,000 180 Aggregate interface containing 3 Selected ports 66,666 160 Aggregate interface containing 4 Selected ports 50,000 140 1000 Mbps Single port 4 20,000 20 Aggregate interface containing 2 Selected ports 10,000 18 Aggregate interface containing 3 Selected ports 6666 16 Aggregate interface containing 4 Selected ports 5000 14 10 Gbps Single port 2 2000 2 Aggregate interface containing 2 Selected ports 1000 1 Aggregate interface containing 3 Selected ports 666 1 Aggregate interface containing 4 Selected ports 500 1 Configuration restrictions and guidelines • When it calculates path cost for an aggregate inte rface, IEEE 802.1t takes into account the number of Selected ports in its aggregation group, but IEEE 802.1d-1998 does not. The calculation formula of IEEE 802.1t is: Path cost = 200,000,000/link speed (in 100 kbps), where link speed is the sum of the link speed values of the Selected ports in the aggregation group. • When multiple ports operate at a rate higher than 10 Gbps and the standard for default path cost calculation is dot1d-1998 or legacy, the path cost of a single port or an aggregate interface takes the smallest value. As a result, the forwarding pat h selected might not be optimal. To solve this problem, use dot1t as the standard for default path cost calculation, or manually set the path cost for a port ( Configuring path costs of ports ). Configuration procedure To specify a standard for the device to use when it calculates the default path cost: Step Command Remarks 1. Enter system view. system-view N/A
87
Step Command Remarks
2. Specify a standard for the
device to use when it
calculates the default path
costs of its ports. stp pathcost-standard
{ dot1d-1998 | dot1t | legacy } Optional.
legacy by default.
Configuring path costs of ports
When the path cost of a port changes, the system re-c alculates the role of the port and initiates a state
transition.
To configure the path cost of ports:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter interface view or port
group view.
• Enter Layer 2 Ethernet interface view or
Layer 2 aggregate interface view:
interface interface-type
interface-number
• Enter port group view:
port-group manual port-group-name Use one of the commands.
3.
Configure the path cost of the
ports.
• In STP/RSTP mode:
stp cost cost
• In PVST mode:
stp vlan vlan-list cost cost
• In MSTP mode:
stp [ instance instance-id ] cost cost Use one of the commands.
By default, the system
automatically calculates the
path cost of each port.
Configuration example
# In MSTP mode, specify the device to calculate the default path costs of its ports by using IEEE
802.1d-1998, and set the path cost of GigabitEthernet 1/0/3 to 200 on MSTI 2.
system-view
[Sysname] stp pathcost-standard dot1d-1998
[Sysname] interface gigabitethernet 1/0/3
[Sysname-GigabitEthernet1/0/3] stp instance 2 cost 200
# In PVST mode, specify the device to calculate the default path costs of its ports by using IEEE
802.1d-1998, and set the path cost of GigabitEthernet 1/0/3 to 2000 on VLANs 20 through 30.
system-view
[Sysname] stp mode pvst
[Sysname] stp pathcost-standard dot1d-1998
[Sysname] interface gigabitethernet 1/0/3
[Sysname-GigabitEthernet1/0/3] stp vlan 20 to 30 cost 2000
88 Configuring the port priority When the priority of a port changes, MSTP re-calculates the role of the port and initiates a state transition. The priority of a port is an important factor in de termining whether the port can be elected as the root port of a device. If all other conditions are the same, the port with the highest priority will be elected as the root port. On a spanning tree device, a port can have different priorities and play different roles in different spanning trees, so that data of different VLANs can be propagated along different physical paths, implementing per-VLAN load balancing. You can set port priority values based on the actual networking requirements. To configure the priority of a port or a group of ports: Step Command Remarks 1. Enter system view. system-view N/A 2. Enter interface view or port group view. • Enter Layer 2 Ethernet interface view or Layer 2 aggregate interface view: interface interface-type interface-number • Enter port group view: port-group manual port-group-name Use one of the commands. 3. Configure the port priority. • In STP/RSTP mode: stp port priority priority • In PVST mode: stp vlan vlan-list port priority priority • In MSTP mode: stp [ instance instance-id ] port priority priority Use one of the commands. The default setting is 128. Configuring the port link type A point-to-point link directly connects two devices. If two root ports or designated ports are connected over a point-to-point link, they can rapidly transition to the forwarding state after a proposal-agreement handshake process. Configuration restrictions and guidelines • You can configure the link type as point-to-point for a Layer 2 aggregate interface or a port that operates in full duplex mode. HP recommends you to use the default setting and let the device to automatically detect the port link type. • The stp point-to-point force-false or stp point-to-point force-true command configured on a port in MSTP or PVST mode is effective for all MSTIs or VLANs. • If the physical link to which the port connects is not a point-to-point link but you set it to be one, the configuration might bring a temporary loop. Configuration procedure To configure the link type of a port or a group of ports:
89
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter interface view or
port group view.
• Enter Layer 2 Ethernet interface view or Layer
2 aggregate interface view:
interface interface-type interface-number
• Enter port group view:
port-group manual port-group-name Use one of the
commands.
3. Configure the port link
type. stp point-to-point
{ auto | force-false |
force-true } By default, the link type is
auto
where the port
automatically detects the
link type.
Configuring the mode a port uses to
recognize/send MSTP packets
A port can receive/send MSTP pac kets in the following formats:
• dot1s —802.1s-compliant standard format
• legacy —Compatible format
By default, the packet format recognition mode of a port is auto. The port automatically distinguishes the
two MSTP packet formats, and determines the format of packets that it will send based on the recognized
format.
You can configure the MSTP packet format on a port. When operating in MSTP mode after the
configuration, the port sends and receives only MSTP packets of the format that you have configured to
communicate with devices that send packets of the same format.
MSTP provides MSTP packet format incompatibility guard. In MSTP mode, if a port is configured to
recognize/send MSTP packets in a mode other than auto, and if it receives a packet in a format different
from the specified type, the port becomes a designat ed port and remains in the discarding state to
prevent the occurrence of a loop.
MSTP provides MSTP packet format frequent change gu ard. If a port receives MSTP packets of different
formats frequently, the MSTP packet format configuration contains errors. If the port is operating in MSTP
mode, it will be shut down for protection. Ports disabled in this way can be re-activated after a detection
interval. For more information about the detection interval, see Fundamentals Configuration Guide.
To configure the MSTP packet format to be supported on a port or a group of ports:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter interface view or
port group view.
• Enter Layer 2 Ethernet interface view or Layer 2
aggregate interface view:
interface interface-type interface-number
• Enter port group view:
port-group manual port-group-name Use one of the
commands.