On S series switches, what are the methods of defining the values of Hold and Keepalive timers on BGP peers

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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.

Other related questions:
How to set the durations of the Hold timer and Keepalive timer of the BGP peer
You can run the peer timer command to set the durations of the Hold timer and Keepalive timer. This command specifies the timeout period of the BGP connection and the interval to send the Keepalive message. A longer timeout period can relieve the impact of link flapping, whereas a shorter timeout period makes the timer rapidly perceive link changes. After connections are established between two peers, the durations of the two timers are negotiated by the two peers and the shorter durations are adopted.

What is the value range of the AS number for BGP on S series switches
The value range of the BGP AS number varies according to the versions of S series switches. 1. V100R002 and earlier versions: The value is an integer that ranges from 1 to 65535. 2. V100R003 to V200R001: The value can contain either two bytes or four bytes. A 2-byte AS number is in the x format. Here, "x" is an integer ranging from 1 to 65535. A 4-byte AS number is in the x.y format. Here, "x" and "y" are integers ranging from 1 to 65535 and 0 to 65535 respectively. 3. V200R002 and later versions: The value can contain either two bytes or four bytes. A 2-byte AS number is in the x format. Here, "x" is an integer ranging from 1 to 4294967295. A 4-byte AS number is in the x.y format. Here, "x" and "y" are integers ranging from 1 to 65535 and 0 to 65535 respectively. Note: You can type bgp ? in the system view in any version to display the specific value range. The following takes V200R007 as an example: [SwitchA] bgp ? INTEGER<1-4294967295> AS number in asplain format (number<1-4294967295>) STRING<3-11> AS number in asdot format (number<1-65535>.number<0-65535>)

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

How to troubleshoot the fault of LDP session flapping due to the expiration of KeepAlive Hold timer
If the KeepAlive Hold timer expires, run the display mpls ldp session command to check whether KeepAlive messages are properly sent on the two ends of the LDP session. If not, the system is busy or faulty. If KeepAlive messages are properly sent but the peer end does not receive them, ping the transport address of the TCP connection with the peer end to check the forwarding status.

Meanings of BGP peer status
In addition to the common Idle and Established status, BGP peer also has the following status: 1. active: indicates that the TCP connection of the BGP session has not been established. 2. no neg: indicates that the negotiation is not performed. If IPv4 Unicast is configured at one end, and IPv4 Unicast and IPv4 Multicast are configured at the other end, after the peer is established, you can discover that IPv4 Unicast negotiation succeeds, and the BGP peer is in Established status. However, the IPv4 Multicast is in no neg status in that IPv4 Multicast is not configured at one end. 3. Idle (Admin): indicates the BGP peer is proactively disabled, and there is no attempt to establish it again. If the peer ignore command is executed, or this peer is set to be down through the MIB, this peer remains in this status.

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