Dear experts, Understand this is a question on an old cisco IOS but need some input and advice from you experts. I have an old cisco switch 4006 running on the old Cisco CatOS 4006 7.6(17) Currently I need to reload the configuration. Based on the previous old configuration. the show run shows the following "set spantree portinstancecost 2/3 cost -1 mst" However, when I tried to enter this command in the configuration mode, it rejected The error message came out "invalid range" But when I set it to "set spantree portinstancecost 2/3 cost 1 mst" - the switch accepted the command - My question, if the CatOS does not allow me to input negative value, how did the show run came out with "-1"? - Will it work the same way if I put "1" or I need to do something to make it "-1" on the configuration. Any advice, feedback is deeply appreciated. many thanks!
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Hi guys, I was reading through the topic on Ether-Channels, and I'm quite confused, and need your guys guidance.. taken from a book im reading, For example, an EtherChannel consisting of two links bundled together requires a 1-bit index. If the index is 0, link 0 is selected; if the index is 1, link 1 is used. Either the lowestorder address bit or the XOR of the last bit of the addresses in the frame is used as the index. A four-link bundle uses a hash of the last 2 bits. Likewise, an eight-link bundle uses a hash of the last 3 bits. The hashing operation’s outcome selects the EtherChannel’s outbound link As an example, consider a packet being sent from IP address 192.168.1.1 to 172.31.67.46. Because EtherChannels can be built from two to eight individual links, only the rightmost (least-significant) 3 bits are needed as a link index. From the source and destination addresses, these bits are 001 (1) and 110 (6), respectively. For a two-link EtherChannel, a 1-bit XOR is performed on the rightmost address bit: 1 XOR 0 = 1, causing Link 1 in the bundle to be used. A four-link EtherChannel produces a 2-bit XOR: 01 XOR 10 = 11, causing Link 3 in the bundle to be used. Finally, an eight-link EtherChannel requires a 3-bit XOR: 001 XOR 110 = 111, where Link 7 in the bundle is selected. From what I have understand... it is possible for us to build and configure EtherChannels from 2 to 8 individual links. My question is.. 1) So it is possible to build Etherchannels with 3, 5, 6 or 7 individual links? 2) if so, a two-link etherchannel , they uses a 1-bit index... and only the rightmost least significant bits are needed as link index. - for a four-link etherchannel, they uses a 2-bit, and for an eight-link bundle uses 3bits as the index... so in that case, how many bits do etherchannel uses for a 3-link, 5-link, 6 and 7-link bundles? please kindly direct me in the right direction ... thanks... Regards, Jason
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