comments inline ""Michael Williams"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Hey all. I came across something and I can't find a good answer anywhere. > So here goes. > > There is a 7500 router with multiple T1s that go to many remote sites. Some > of these remote sites use multiple T1 lines. These are configured with PPP > Multilink and Virtual Templates. > > I know that when configuring MLP without Virtual Templates, you can specify > a multilink group (bundle). However, we aren't specifying a bundle or group > number on our serial interfaces. We simply have them using MLP and then a > "multilink virtual-template 1" command. > > Here's my question. How does the router (the Virtual Template) know which > line to put in which bundle? Does it use a neighbor-type relationship to > determine which links need to be part of which bundles?
If you are using PPP authentication, then it will use the authenticated name of the other side to determine what link goes with what bundle. It can also use a unique identifying value called the endpoint-discriminator, which is a a number that is negotiated when multilink is first negotiated in LCP. It can use both authenticated name and endpoint discriminator, and this is the default behavior. This behavior can be controlled using "multilink bundle-name" commands. > > Here is a sample of the output from the "hub" router: > > ------------------------------------------------------ > Router#show ppp mul > > Bundle Site1, 2 members, Master link is Virtual-Access1 > 696774 lost fragments, 77484296 reordered, 0 unassigned, sequence > 0x216AF0/0xBD6863 rcvd/sent > 317583 discarded, 17 lost received, 34/255 load > > Member Links: 2 > Serial5/0/0 > Serial5/0/1 > > Bundle Site2, 2 members, Master link is Virtual-Access2 > 483 lost fragments, 4395802 reordered, 0 unassigned, sequence > 0xB0B211/0x7718D rcvd/sent > 145 discarded, 0 lost received, 245/255 load > > Member Links: 2 > Serial11/0/0 > Serial11/0/1 > ------------------------------------------------------ > > So again, how did the Virtual-Template know to group S5/0/0 and S5/0/1 into > a bundle? Again, see above. Probably a combo of the authenticated name and the endpoint discriminator. > > A secondary question: What's the advantage(s) to using Virtual-Templates > over simply configuring the MLP bundles directly? In my experience, doing it the with direct MLP bundle command is flakier. I've had several weird multilink problems that I solved just reverting to the virtual-template method. The virtual-template way has given me less problems. But the direct MLP way is more intuitive. But as a side-note, I often see MPPP on serial interfaces as sort of a fool's errand, unless perhaps you are linking a Cisco router to another vendor (MPPP on dial networks like ISDN is still useful). The only really good reason to use MPPP on a serial link is for link load-balancing. But if you just need link load-balancing, then all I have to say is "CEF". End of story. CEF accomplishes the same thing, and is overall faster, less resource-intensive, and more stable than MPPP. > > If anyone has a good link or document about how Cisco implements MLP with > and without Virutal-Templates, let me know. Aside from straight "here's how > to configure" documents, I can't find any good info. It's the same. With the direct way, the multilink interface in effect becomes the virtual-template. > > Thanks! > Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=27096&t=26877 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
