ooh VSTP/PVST+ interop. Boy have we had some fun here over the years.. Cisco PVST+ sends IEEE and Cisco BPDUs on the *native* VLAN and Cisco BPDUs for each VLAN that is tagged on an interface. Juniper VSTP only sends IEEE BPDUs on the native VLAN 1 (or did as of 11.4) but sends Cisco BPDUs for each tagged VLAN.
A gotcha to watch out for is if you are using "default" VLAN in Junos as your native, you need to manually set the VLAN-ID to 1 or the VSTP config will not pick it up: set vlan default vlan-id 1 There is a change in 12.2 regarding something similar to this: "VSTP compatibility with Cisco PVST+—When you configure VSTP using the set protocol vstp vlan all configuration mode command, VLAN ID 1 is now excluded, thus making Junos OS VSTP compatible with Cisco PVST+. To include VLAN ID 1 in the VSTP VLAN, you must now add it explicitly using the set protocol vstp vlan 1 configuration mode command." If you're in a pure Juniper environment, you don't need to worry too much though - as long as you have a common native VLAN (or even if you have none) everything generally works pretty well provided you make sure you're not running an EX software version affected by this bad boy: http://kb.juniper.net/InfoCenter/index?page=content&id=KB22111&cat=EX_SERIES&actp=LIST&smlogin=true If your VLAN count is getting up over 100, consider MSTP - the CPU thrashing on a 3550 or 3750 when they all reconverge has some NASTY side-effects (like delaying the sending of BPDUs, causing the issue to spiral even further). On 11/12/2012, at 7:28 AM, Mike Azevedo <[email protected]> wrote: > you can bcast storm your network to a halt if you are not careful. Use VSTP > on juniper side to match the cisco PVST+. I believe Juniper's RSTP uses one > instance of spanning tree over the physical network not an instance per vlan > like cisco's implementation. I would also watch out for vlan 1. > > > > ----- Original Message ----- > > From: "Benny Amorsen" <[email protected]> > To: "harbor235" <[email protected]> > Cc: "Juniper List" <[email protected]> > Sent: Monday, December 10, 2012 3:16:10 PM > Subject: Re: [j-nsp] juniper cisco switch interconnection > > harbor235 <[email protected]> writes: > >> Has anyone connected a Juniper EX series switch with a Cisco switch (I have >> a 3550)? > > Yes > >> Do you use a standard crossover cable? MDIX? > > I have only attempted 1Gbps, that just worked with a straight cable. > >> Any Layer 2 issues with RSTP and PVST+? > > It seems to work so far... > >> Any specific configuration required to make it work? > > Avoid VLAN 1. You can probably make VLAN 1 work if you try, but for me > it was easier to simply not use it. > > > /Benny > > _______________________________________________ > juniper-nsp mailing list [email protected] > https://puck.nether.net/mailman/listinfo/juniper-nsp > > _______________________________________________ > juniper-nsp mailing list [email protected] > https://puck.nether.net/mailman/listinfo/juniper-nsp > _______________________________________________ juniper-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/juniper-nsp
