Cisco WS-X6708-10G-3CXL= - 10 Gigabit Ethernet Module Instrukcja Użytkownika Pobierz pdf (Strona 47)

White Paper

Enhanced PAgP

With the introduction of Cisco Virtual Switching System in the first software release, an enhancement to the PAgP

protocol (Enhanced PAgP or PAgP+) has been implemented to assist in the dual-active detection. A list of all

software releases for respective switch platforms supporting Enhanced PAgP is included in Table 1 (Figure 35).

Figure 35. Dual-Active Detection Mechanisms

The result of this detection is that the standby virtual switch (switch 2) always transitions to become an active virtual

switch and the active virtual switch (switch 1) always enters into recovery mode.

Upon the detection of VSL going down on switch 2, the switch will immediately transmit a PAgP message on all port

channels enabled for Enhanced PAgP dual-active detection, with a Type-Length-Value (TLV) containing its own

Active ID = 2. When the access switch receives this PAgP message on any member of the port channel, it detects

that it has received a new active ID value and considers such a change as an indication that it should consider switch

2 to be the new active virtual switch. In turn, the access switch modifies its local active ID value to Active ID = 2 and

immediately sends a message to both virtual switches on all members of the port channel with the new Active ID = 2

to indicate that it now considers switch 2 to be the active virtual switch.

Form this point onward, the access switch sends TLVs containing Active ID = 2 to the virtual switches in all its

regularly scheduled PAgP messages.

Use the following commands to configure the Cisco Virtual Switching System to take advantage of dual-active

detection using Enhanced PAgP:

vss#conf t

Enter configuration commands, one per line. End with CNTL/Z.

vss(config)#switch virtual domain 10

vss(config-vs-domain)#dual-active detection pagp

vss(config-vs-domain)#dual-active trust channel-group 20

vss(config-vs-domain)#

To verify the configuration and make sure that Enhanced PAgP is compatible with its neighbors, issue the following

command:

vss#sh switch virtual dual-active pagp

PAgP dual-active detection enabled: Yes

PAgP dual-active version: 1.1

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Cisco WS-X6708-10G-3CXL= - 10 Gigabit Ethernet Module Instrukcja Użytkownika Strona 47