Functions and default values of IS-IS timers on S series switches

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The functions and default values of IS-IS timers are as follows:
CSNP Timer
10s
csnp-interval: specifies the interval for sending CSNPs on a broadcast network.

HELLO Timer
10s (3s for the DIS)
Specifies the interval for sending Hello messages.
lsp-retransmit Timer
5s
Specifies the interval for re-sending LSP packets, that is, the interval between marking LSP packets with SRM on a P2P link and sending LSP packets.

lsp-throttle Timer
50 ms
Specifies the minimum interval for sending LSP packets.

lsp-generation Timer
2s
Specifies the maximum interval for generating LSP packets.

lsp-max-age Timer
1200s
Specifies the maximum Keepalive time of an LSP generated by the current IS-IS process, which is configured using the timer lsp-max-age command.

lsp-refresh Timer
900s
Specifies the LSP refresh interval, which is configured using the timer lsp-refresh command.

spf
10s
Specifies the maximum delay in route calculation.

PSNP Timer
5s
Specifies the interval between marking PSNPs with SSN and sending PSNPs.

Specifies the minimum interval for sending packets on a broadcast network.
50 ms

Specifies the interval between marking LSP packets with SRM and sending LSP packets.

Other related questions:
Calculate the backpressure timer value of PFC frames
Priority-based Flow Control (PFC) is a flow control mechanism based on priority. After the data center bridging (DCB) function is enabled on a switch and negotiation succeeds, the switch stops sending packets in the corresponding priority queue when it receives PFC frames. Backpressure timer value = 512 x Time(n)/Interface bandwidth Time(n) indicates the backpressure timer value. The unit is the time an interface uses to send 521 bits.

On S series switches, what are the methods of defining the values of Hold and Keepalive timers on BGP peers
For S series switches that support BGP, the value of Hold and Keepalive timers can be set with the peer timer command. This command specifies the hold time when the BGP connection is interrupted and the interval for sending Keepalive messages. Large values of the two timers reduce the impact of link flapping, and small values enable the device to detect link changes. After the peer relationship is set up, the values of the two timers are negotiated by both peers, and the smaller ones are used.

Enable and disable PoE on an S series switch
Enable or disable the PoE function on S series switches:

1. By default, the PoE function is enabled on an interface
2. Enable or disable PoE power supply.
<HUAWEI>system-view
[HUAWEI]interface gigabitethernet 1/0/0
[HUAWEI-GigabitEthernet1/0/0]undo poe enable  //Disable PoE power supply.
[HUAWEI-GigabitEthernet1/0/0]poe enable       //Enable PoE power supply.

The downlink electrical interfaces of PoE switches support PoE power supply, with up to 30 W power on each interface. The maximum power supply distance is 100 m.
Only ES0D0G48VA00 (S7700)/LE0DG48VEA00 (S9300) cards of modular switches (S7700/S9700/S9300/S12700) support PoE power supply.

If the switch connects to 48 V standard PoE powered devices but cannot negotiate power supply capabilities with the devices, you can run poe force-power on the interfaces to forcibly power on the devices.


Default MUX VLAN configuration on S series switch
By default, the MUX VLAN function is disabled on interfaces of S series switches (except S1700). To enable this function on an interface, run the port mux-vlan enable command on the interface.

RD value of a VPN instance on S series switches
Traditional BGP cannot process the VPN routes that have overlapping address spaces. Assume that both VPN1 and VPN2 use addresses on the network segment 10.110.10.0/24, and each of them advertises a route destined for this network segment. The local PE identifies the two VPN routes based on VPN instances and sends them to the remote PE. Because routes from different VPNs cannot work in load-balancing mode, the remote PE adds only one of the two routes based on BGP route selection rules. As a result, the route to the other VPN is lost. To ensure that VPN routes of VPNs with overlapping address spaces are correctly processed, PE devices use MP-BGP to advertise VPN routes and use the VPN-IPv4 address family to identify the routes. RDs distinguish the IPv4 prefixes with the same address space. IPv4 addresses with RDs are VPN-IPv4 addresses (VPNv4 addresses). After receiving IPv4 routes from a CE, a PE converts the routes to globally unique VPN-IPv4 routes and advertises the routes on the public network. The following is a configuration example: # ip vpn-instance vpna ipv4-family route-distinguisher 200:1 vpn-target 111:1 export-extcommunity vpn-target 111:1 import-extcommunity #

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