uplinkfast と backbonefastをやってみる。
例の三角形トポロジにおいて、blocking portを持っているスイッチの、fwd portの線を抜いて見ると、root portがダウンするためaltn portがlearning, listening, forwardingと遷移する。
00:40:14: STP: VLAN0001 new root port Fa0/5, cost 38
00:40:14: STP: VLAN0001 Fa0/5 -> listening
00:40:15: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/12, changed state to down
00:40:16: STP: VLAN0001 sent Topology Change Notice on Fa0/5
00:40:16: %LINK-3-UPDOWN: Interface FastEthernet0/12, changed state to down
00:40:29: STP: VLAN0001 Fa0/5 -> learning
00:40:44: STP: VLAN0001 Fa0/5 -> forwarding
今度はuplinkfastを有効にしてみる。
2950_2(config)#spanning-tree uplinkfast
2950_2(config)#
00:43:30: setting bridge id (which=1) prio 49153 prio cfg 49152 sysid 1 (on) id C001.0008.e32e.5980
00:43:30: STP: VLAN0001 Fa0/5 -> blocking (uplinkfast)
00:43:30: %SPANTREE_FAST-7-PORT_FWD_UPLINK: VLAN0001 FastEthernet0/12 moved to Forwarding (UplinkFast).
00:43:30: STP: VLAN0001 sent Topology Change Notice on Fa0/12
00:43:30: setting bridge id (which=1) prio 49154 prio cfg 49152 sysid 2 (on) id C002.0008.e32e.5980
00:43:30: setting bridge id (which=1) prio 49155 prio cfg 49152 sysid 3 (on) id C003
2950_2(config)#.0008.e32e.5980
00:43:30: setting bridge id (which=1) prio 49156 prio cfg 49152 sysid 4 (on) id C004.0008.e32e.5980
00:43:30: setting bridge id (which=1) prio 49157 prio cfg 49152 sysid 5 (on) id C005.0008.e32e.5980
00:43:30: setting bridge id (which=1) prio 49158 prio cfg 49152 sysid 6 (on) id C006.0008.e32e.5980
00:43:30: setting bridge id (which=1) prio 49159 prio cfg 49152 sysid 7 (on) id C007.0008.e32e.5980
00:43:30: setting bridge id (which=1) prio 49160 prio cfg 49152 sysid 8 (on) id C008.0008.e32e.5980
00:43:30: setting bridge id (which=1) prio 49161 prio cfg 49152 sysid 9 (on) id C009.0008.e32e.5980
00:43:30: setting bridge id (which=1) prio 49162 prio cfg 49152 sysid 10 (on) id C00A.0008.e32e.5980
00:43:30: setting bridge id (which=1) prio 49186 prio cfg 49152 sysid 34 (on) id C022.0008.e32e.5980
00:43:30: setting bridge id (which=1) prio 49251 prio cfg 49152 sysid 99 (on) id C063.0008.e32e.5980
今度はlink downが起きると瞬時にalt portがforwardingになる。
00:46:38: STP: VLAN0001 new root port Fa0/5, cost 3038
00:46:38: %SPANTREE_FAST-7-PORT_FWD_UPLINK: VLAN0001 FastEthernet0/5 moved to Forwarding (UplinkFast).
00:46:39: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/12, changed state to down
00:46:40: STP: VLAN0001 sent Topology Change Notice on Fa0/5
00:46:40: %LINK-3-UPDOWN: Interface FastEthernet0/12, changed state to down
2950_2#
backbonefastは、自分のportではない間接linkdownの際に機能する。Root Link Queryの要求と応答によって機能するため、ネットワーク上のすべてのＳＷで設定する必要がある。
また、portfastやuplinkfastと違い、瞬時にalt portをアップさせることはできない。
ちなみに私はbackbonefastをサポートしているＳＷを2台しか持っていないので実際の動作は確認できない。