Hi Imran, When router sends a frame , it sends a untagged frame which it believes that native vlan is 20 , and that frame reaches the switch and switch see the frame as untagged as think that it belongs to native vlan 30 and floods it to all ports which belong to this vlan 300 ( access port for vlan 300 and trunk ports which carry all vlans ) .
I didnt understood the point that ur talking about that ARP is a layer 2 broadcast i agree. How can u say that it is unicast for Layer 3 When a router generates a arp for ip 20.1.1.1 . tthe layer 2 header will be the source MAC of its own MAC and the dest MAC as broadcast only right ..... and inside the ARP header the Source IP is its won IP and Target IP is 20.1.1.1 . and source MAC will be its own MAC and Target MAC will be 000000.. So There is no IP header in ARP packet.. So where does unicast comes into picture for LAyer 3 ? Even router has to create a broadcast packet for ARP. So now router sends a arp packet to create L2 header . It send a UNTAGGED frame as it belongs to a native vlan of 20 and it hits switch and it updates the source MAC and sees it is a native vlan and it forwards to all trunk ports and also access ports for vlan 10. , So now another switch receives it and sends it to the destined host. SO Imran i guess , I am correct. Correct me if i am wrong Thank You So when the switch receives the frame and see this a broadcast frame. it wil broadcast it to all ports except to that port which came in. On Sun, Dec 11, 2011 at 2:54 PM, Imran Ali <[email protected]> wrote: > *kid , your question was answered perfectly by Rob.* > > *first off what is the use of trunk . ?* > > *Ans: to carry traffic of more than one vlan* . > > *can i say if trunk is up , everthing is fine ?* > > *no many factors may prevent proper decapsulation and rechability is > broken* > > *can you give me example when even though trunk is up . end hosts are not > talking ?* > > yes . "allowed vlan list " filtering traffiic and " native vlan mismatch " > > *ok can you expalin me how native vlan mismatch prevent end host talking > to each other in same vlan ?* > > *look at config provied in above mail . * > ** > *router's native vlan is 20 . and switch native vlan is 30. so when > router send packets to an ip in valn 20 . it sends them untagged , and i > repeat it with diff words " in its native " form like the one received > from PC . * > ** > *Swithch when it receives the packet believes it belongs to Vlan 30 , > because here in switch* vlan 30 is Native . > > *what made switch believe it belongs to vlan 30 ?* > > *because it is assumed that when ever i received a frame with out any > vlan tag it belongs to native vlan * > > *so it searches vlan 30 . This was a first packet . * > ** > *to build a packet router should know the mac address . so this paket is > ARP packet . * > ** > *how can you say that ?* > ** > *arp cache was empty as this is first time they are talking * > > *ok i agree it was arp packet sourced from router to switch , but what > happened to it ?* > > *for the switch its just a frame . and it made an assumption that it > blongs to ITS NATIVE vlan that is vlan 30 .* > > *ok what happened next . ?* > > *arp is broadcast at layer 2 and unicast at layer 3 . so swithch now > prepares for broadcasting the frame IN VLAN 30.* > > *that's fine but why it dint answered ?* > > > > *kid i leave this question to be ansered by you . if you have CCNA > concepts fresh in your mind , you will understand above explantion and > also be able to answer the question* . > > *OH that's why rechability is broken between the ip that belong to same > vlan due to mismatch in Natve vlan ?* > > *absolutely !* > > *so NATIVE VLAN MISMATCH is bad ?* > > *exactly > * > On Sat, Dec 10, 2011 at 7:03 PM, CCIE KID <[email protected]> wrote: > >> Hi, >> >> Still my issue is not been resolved. >> So what can be the conclusion man >> >> Can any expert can pitch in an answer for that >> >> >> On Sat, Dec 10, 2011 at 8:28 PM, me you <[email protected]> wrote: >> >> > *CONCLUSION: We do NOT have full reachability despite the vlan >> mismatch.* >> >> > >> > I would agree with you that your set up work, but I disagree with a >> > general statement that Native Vlan mismatch does not matter between a >> > router and switch. 1 2811, 3 subinterfaces and 1 3750 trunkport with 3 >> > vlans. Neither of the native vlans have reachability. >> > >> > >> > interface FastEthernet0/0 >> > >> > no ip address >> > >> > duplex auto >> > >> > speed auto >> > >> > ! >> > >> > interface FastEthernet0/0.10 >> > >> > encapsulation dot1Q 10 >> > >> > ip address 10.1.1.1 255.255.255.0 >> > >> > ! >> > >> > interface FastEthernet0/0.20 >> > >> > encapsulation dot1Q 20 native >> > >> > ip address 20.1.1.1 255.255.255.0 >> > >> > ! >> > >> > interface FastEthernet0/0.30 >> > >> > encapsulation dot1Q 30 >> > >> > ip address 30.1.1.1 255.255.255.0 >> > >> > >> > >> > 3750 >> > >> > interface GigabitEthernet1/0/1 >> > >> > switchport trunk encapsulation dot1q >> > >> > switchport trunk native vlan 30 >> > >> > switchport mode trunk >> > >> > end >> > >> > >> > interface Vlan1 >> > >> > no ip address >> > >> > ! >> > >> > interface Vlan10 >> > >> > ip address 10.1.1.2 255.255.255.0 >> > >> > ! >> > >> > interface Vlan20 >> > >> > ip address 20.1.1.2 255.255.255.0 >> > >> > ! >> > >> > interface Vlan30 >> > >> > ip address 30.1.1.2 255.255.255.0 >> > >> > >> > >> > 3750(config)#do ping 10.1.1.1 >> > >> > >> > Type escape sequence to abort. >> > >> > Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds: >> > >> > !!!!! >> > >> > Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/9 ms >> > >> > 3750(config)#do ping 20.1.1.1 >> > >> > >> > Type escape sequence to abort. >> > >> > Sending 5, 100-byte ICMP Echos to 20.1.1.1, timeout is 2 seconds: >> > >> > ..... >> > >> > Success rate is 0 percent (0/5) >> > >> > 3750(config)#do ping 30.1.1.1 >> > >> > >> > Type escape sequence to abort. >> > >> > Sending 5, 100-byte ICMP Echos to 30.1.1.1, timeout is 2 seconds: >> > >> > ..... >> > >> > Success rate is 0 percent (0/5) >> > >> > >> > Deb ip icmp on *Dec 10 14:36:59.527: ICMP: echo reply sent, src >> 10.1.1.1, >> > dst 10.1.1.2 >> > >> > *Dec 10 14:36:59.527: ICMP: echo reply sent, src 10.1.1.1, dst 10.1.1.2 >> > >> > *Dec 10 14:36:59.531: ICMP: echo reply sent, src 10.1.1.1, dst 10.1.1.2 >> > >> > *Dec 10 14:36:59.531: ICMP: echo reply sent, src 10.1.1.1, dst 10.1.1.2 >> > >> > *Dec 10 14:36:59.535: ICMP: echo reply sent, src 10.1.1.1, dst 10.1.1.2 >> > >> > --More-- >> > >> > *Dec 10 14:37:04.179: ICMP: echo reply sent, src 20.1.1.1, dst 30.1.1.2 >> > >> > --More-- >> > >> > *Dec 10 14:37:06.183: ICMP: echo reply sent, src 20.1.1.1, dst 30.1.1.2 >> > >> > --More-- >> > >> > *Dec 10 14:37:08.187: ICMP: echo reply sent, src 20.1.1.1, dst 30.1.1.2 >> > >> > --More-- >> > >> > *Dec 10 14:37:10.195: ICMP: echo reply sent, src 20.1.1.1, dst 30.1.1.2 >> > >> > --More-- >> > >> > *Dec 10 14:37:12.199: ICMP: echo reply sent, src 20.1.1.1, dst 30.1.1.2 >> > >> > >> > To say vlan mismatch between a router and a switch does not matter is >> > misleading or wrong. We could say if "this is that way" then "that is >> this >> > way" "that and this will work":) >> > >> > >> > Rob >> > >> > >> > >> > On Sat, Dec 10, 2011 at 5:39 PM, CCIE KID <[email protected]> wrote: >> > >> >> Hi Oyebande, >> >> >> >> Thank u mate. U confirmed my understanding. So from router to switch it >> >> doesnt matter to match the native vlan on both sides. >> >> Unlike Switch to Switch to form trunk port ,native vlans should match >> to >> >> form trunk link >> >> to pass data traffic on that link. >> >> >> >> Thanks all for their confirmation >> >> >> >> >> >> >> >> On Sat, Dec 10, 2011 at 5:19 PM, Oluwagbenga Oyebande < >> >> [email protected]> wrote: >> >> >> >>> >> >>> *CONCLUSION: We have full reachability despite the vlan mismatch.* >> >>> * >> >>> * >> >> >>> * >> >>> Three routers and one switch. >> >>> >> >>> >> >>> * >> >>> * >> >>> R2811(Fa0/0.1)-------------TRUNK-LINK-----------------------Cat3550 >> >>> (Fa0/1) >> >>> * >> >>> * >> >>> native vlan 20 >> >>> native vlan 10 >> >>> >> >>> >> >>> R3825 >> >>> (Gi0/0.1) >> >>> ------------- >> >>> TRUNK-LINK >> >>> ----------------------- >> >>> Cat3550 (Gi0/2) >> >>> native vlan 30 >> >>> >> >>> native vlan 10 >> >>> >> >>> *R2811-forvlan10(Fa0/0)--* >> >>> ACCESS-LINK >> >>> *-----* >> >>> Cat3550 (Fa0/4) >> >>> * >> >>> * >> >>> >> >>> explicitly configured in vlan 10 as access port >> >>> >> >>> I included the third link to clear all doubts about expected behaviour >> >>> of vlan 10 connected devices. >> >>> >> >>> >> >>> * >> >>> *Catalyst 3550 Swicth Spec* >> >>> >> >>> Cat3550(config)#do sh vers | i Model num|RELEA >> >>> Cisco IOS Software, C3550 Software (C3550-IPSERVICESK9-M), Version >> >>> 12.2(44)SE3, RELEASE SOFTWARE (fc2) >> >>> Model number: WS-C3550-24-SMI >> >>> * >> >>> * >> >>> *2811 Router Spec* >> >>> >> >>> Router(config)#do sh ver | i image >> >>> System image file is "flash:c2800nm-adventerprisek9-mz.124-24.T2.bin" >> >>> * >> >>> * >> >>> *3825 Router Spec* >> >>> * >> >>> * >> >>> R3825(config-subif)#do sh ver | i Software >> >>> Cisco IOS Software, 3800 Software (C3825-ADVENTERPRISEK9-M), Version >> >>> 12.4(24)T2, RELEASE SOFTWARE (fc2) >> >>> >> >>> *2811 (for vlan 10 ) Router Spec * >> >>> * >> >>> * >> >> >>> R2811-forvlan10(config)#do sh ver | i Software >> >>> Cisco IOS Software, 2800 Software (C2800NM-ADVENTERPRISEK9-M), >> Version >> >>> 12.4(24)T2, RELEASE SOFTWARE (fc2) >> >>> >> >>> >> >>> *CDP *(so we have Fas 0/1 connected to 2811and we have Gig 0/2 >> >> >>> connected to 3825 and Fa0/4 Connected to R2811-forvlan10) >> >>> >> >>> Cat3550(config-if)#do sh cdp nei | i R2811|R3825|ID >> >>> Device ID Local Intrfce Holdtme Capability Platform >> Port >> >>> ID >> >>> R2811-forvlan10 Fas 0/4 123 R S I 2811 >> Fas >> >>> 0/0 >> >>> R2811 Fas 0/1 139 R S I 2811 >> Fas >> >>> 0/0 >> >>> R3825 Gig 0/2 129 R S I 3825 >> Gig >> >>> 0/0 >> >>> >> >>> >> >>> *INTERFACE CONFIG* >> >>> * >> >>> * >> >>> Cat3550(config-if)#do sh run int *fa0/1* >> >>> interface FastEthernet0/1 >> >>> description *TRUNK to R2811* >> >>> switchport trunk encapsulation dot1q >> >>> switchport trunk native vlan 10 >> >>> switchport mode trunk >> >>> end >> >>> >> >>> Cat3550(config-if)#do sh run int fa0/4 >> >>> interface FastEthernet0/4 >> >>> description *ACCESS LINK TO R2811-forvlan10* >> >> >>> switchport access vlan 10 >> >>> switchport mode access >> >>> end >> >>> >> >>> Cat3550(config-if)#do sh run int gi0/2 >> >>> interface GigabitEthernet0/2 >> >>> description *TRUNK to R3825* >> >> >>> switchport trunk encapsulation dot1q >> >>> switchport trunk native vlan 10 >> >>> switchport mode trunk >> >>> end >> >>> >> >>> Cat3550(config-if)#do sh run int vlan 10 >> >>> interface Vlan10 >> >>> ip address 10.1.1.2 255.255.255.0 >> >>> end >> >>> >> >>> Cat3550(config-if)#do sh int status >> >>> Port Name Status Vlan Duplex Speed >> Type >> >>> Fa0/1 TRUNK to R2811 connected trunk a-full a-100 >> >>> 10/100BaseTX >> >>> Fa0/4 ACCESS LINK TO R28 connected 10 a-full a-100 >> >>> 10/100Base >> >>> Gi0/2 TRUNK to R3825 connected trunk a-full a-1000 >> >>> 1000BaseSX >> >>> >> >>> *VLANS* >> >>> * >> >> >>> * >> >>> VLAN Name Status Ports >> >>> ---- -------------------------------- --------- >> >>> ------------------------------- >> >>> 1 default active Fa0/2, Fa0/3, Fa0/5, >> >>> Fa0/6 >> >>> Fa0/7, Fa0/8, Fa0/9, >> >>> Fa0/10 >> >>> Fa0/11, Fa0/12, >> Fa0/13, >> >>> Fa0/14 >> >>> Fa0/15, Fa0/16, >> Fa0/17, >> >>> Fa0/18 >> >>> Gi0/1 >> >>> 10 VLAN0010 active Fa0/4 >> >>> 20 VLAN0020 active >> >>> 30 VLAN0030 active >> >>> >> >>> >> >>> R2811(config-subif)#do sh run int fa0/0.1 >> >>> interface FastEthernet0/0.1 >> >>> description "MISMATCHED NATIVE VLAN 20/10" >> >>> encapsulation dot1Q 20 native >> >>> ip address 10.1.1.1 255.255.255.0 >> >>> end >> >>> >> >>> R3825(config-subif)#do sh run int gi0/0.1 >> >>> interface GigabitEthernet0/0.1 >> >>> description "MISMATCHED NATIVE VLAN 30/10" >> >>> encapsulation dot1Q 30 native >> >>> ip address 10.1.1.3 255.255.255.0 >> >>> end >> >>> >> >>> R2811-forvlan10(config-if)#do sh run int fa0/0 >> >>> interface FastEthernet0/0 >> >>> description "THIS ONE IS AN ACCESS LINK WHICH WE WILL PUT IN VLAN 10 >> ON >> >>> THE SWITCH" >> >>> ip address 10.1.1.4 255.255.255.0 >> >>> duplex auto >> >>> speed auto >> >>> end >> >>> >> >>> >> >>> >> >>> Cat3550(config-if)#do ping 10.1.1.255 >> >>> Type escape sequence to abort. >> >>> Sending 5, 100-byte ICMP Echos to 10.1.1.255, timeout is 2 seconds: >> >>> Reply to request 0 from 10.1.1.3, 1 ms >> >>> Reply to request 0 from 10.1.1.1, 1 ms >> >>> Reply to request 0 from 10.1.1.4, 1 ms >> >>> >> >>> R2811(config-subif)#do ping 10.1.1.255 >> >>> Type escape sequence to abort. >> >>> Sending 5, 100-byte ICMP Echos to 10.1.1.255, timeout is 2 seconds: >> >>> Reply to request 0 from 10.1.1.3, 1 ms >> >>> Reply to request 0 from 10.1.1.2, 1 ms >> >>> Reply to request 0 from 10.1.1.4, 1 ms >> >>> >> >>> >> >>> R3825(config-subif)#do ping 10.1.1.255 >> >>> Type escape sequence to abort. >> >>> Sending 5, 100-byte ICMP Echos to 10.1.1.255, timeout is 2 seconds: >> >>> Reply to request 0 from 10.1.1.2, 4 ms >> >>> Reply to request 0 from 10.1.1.1, 4 ms >> >>> Reply to request 1 from 10.1.1.2, 1 ms >> >>> Reply to request 1 from 10.1.1.1, 1 ms >> >>> Reply to request 1 from 10.1.1.4, 1 ms >> >>> >> >>> R2811-forvlan10(config-if)#do ping 10.1.1.255 >> >>> >> >>> Type escape sequence to abort. >> >>> Sending 5, 100-byte ICMP Echos to 10.1.1.255, timeout is 2 seconds: >> >>> >> >>> Reply to request 0 from 10.1.1.3, 4 ms >> >>> Reply to request 0 from 10.1.1.1, 4 ms >> >>> Reply to request 0 from 10.1.1.2, 4 ms >> >>> >> >>> >> >>> *CONCLUSION: So we have full reachability despite the vlan mismatch.* >> >> >>> >> >>> >> >>> Olugbenga Oyebande >> >>> >> >>> >> >>> >> >>> >> >>>> On Fri, Dec 9, 2011 at 7:38 PM, Oluwagbenga Oyebande < >> >>>> [email protected]> wrote: >> >>>> >> >>>>> Hi CCIE Kid >> >>>>> >> >>>>> I agree with Narottam. I would like to add something to Q2 >> >>>>> >> >>>>> >> >>>>> Answ to Q1. The trunk will form as you have already seen. >> >>>>> >> >>>>> Answ to Q2. If by user traffic you mean IP traffic, then the answer >> >>>>> depends on the IP configuration of your switch's *VLAN 10 SVI. *If >> >> >>>>> you have 10.1.1.0/24 subnet configured on the switch's SVI then IP >> >>>>> traffic should pass in spite of native vlan mismatch. If you have >> another >> >>>>> subnet (or no ip address) configured on it then IP traffic will not >> pass. >> >>>>> * >> >> >>>>> * >> >>>>> >> >>>>> >> >>>>> On Fri, Dec 9, 2011 at 7:45 AM, Narottam Prajapati < >> >>>>> [email protected]> wrote: >> >>>>> >> >>>>>> HI >> >>>>>> >> >>>>>> Native VLAN numbering mismatch will not affect to trunk forming >> >>>>>> process. Trunk will form between both devics. >> >>>>>> >> >>>>>> Regarding Traffic forwarding traffic will forward without any >> tagigng >> >>>>>> due >> >>>>>> to default behaviour of dot1q encapsulation. >> >>>>>> >> >>>>>> When router try to forward traffic to switch frames forwards up to >> >>>>>> switch >> >>>>>> and switch 2 assume that this traffic is for native VLAN traffic >> >>>>>> because >> >>>>>> frames are untaged. >> >>>>>> >> >>>>>> Hi Group >> >>>>>> >> >>>>>> make me correct if any thing is wrong. >> >>>>>> >> >>>>>> Regards, >> >>>>>> Narottam Prajapati >> >>>>>> >> >>>>>> On Fri, Dec 9, 2011 at 11:25 AM, Shaughn Smith < >> [email protected]> >> >>>>>> wrote: >> >>>>>> >> >>>>>> > Your question was answered. A few times. >> >>>>>> > >> >>>>>> > CCIE # 23962 (SP) >> >>>>>> > >> >>>>>> > Sent from my iPhone 4 >> >>>>>> > >> >>>>>> > On 09 Dec 2011, at 7:40 AM, CCIE KID <[email protected]> >> wrote: >> >>>>>> > >> >>>>>> > > Hi all, >> >>>>>> > > >> >>>>>> > > Still my question has not been answered. What will happen if a >> >>>>>> router >> >>>>>> > > connected to a switch is placed in two different native Vlans. >> U >> >>>>>> guys are >> >>>>>> > > all talking about connecting two switches and incorporating two >> >>>>>> different >> >>>>>> > > native vlans. >> >>>>>> > > >> >>>>>> > > My scenario is simple. R1-----------------------Sw1 >> >>>>>> > > >> >>>>>> > > I m using two different native vlans from R1 to Sw1 . Whether >> >>>>>> trunk will >> >>>>>> > > form.? Or if the trunk forms, whether user traffic will be >> able >> >>>>>> to pass >> >>>>>> > > through or not. >> >>>>>> > > >> >>>>>> > > Please reply to my questions >> >>>>>> > > >> >>>>>> > > Thank You >> >>>>>> > > >> >>>>>> > > On Fri, Dec 9, 2011 at 4:23 AM, George J. Sanchez < >> >>>>>> [email protected] >> >>>>>> > >wrote: >> >>>>>> > > >> >>>>>> > >> I've seen plenty of customers networks with native vlan >> >>>>>> mismatches, >> >>>>>> > >> traffic will pass. With that being said, newer code may fix >> >>>>>> different >> >>>>>> > >> "features" that previous codes had issues with. >> >>>>>> > >> >> >>>>>> > >> Regards, >> >>>>>> > >> Joe Sanchez >> >>>>>> > >> >> >>>>>> > >> On Dec 8, 2011, at 1:28 PM, Narbik Kocharians < >> [email protected] >> >>>>>> > >> >>>>>> > wrote: >> >>>>>> > >> >> >>>>>> > >>> This is what i was referring to: >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> R1 s F0/0 is connected to SW1 s port F0/1 >> >>>>>> > >>> >> >>>>>> > >>> R2 s F0/1 is connected to SW2 s port F0/2 >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> SW1 s F0/19 is connected to SW2 s F0/19 >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> *SW1#sh run int f0/19 | B inter* >> >>>>>> > >>> >> >>>>>> > >>> interface FastEthernet0/19 >> >>>>>> > >>> >> >>>>>> > >>> switchport trunk encapsulation dot1q >> >>>>>> > >>> >> >>>>>> > >>> switchport trunk native vlan 10 >> >>>>>> > >>> >> >>>>>> > >>> switchport mode trunk >> >>>>>> > >>> >> >>>>>> > >>> end >> >>>>>> > >>> >> >>>>>> > >>> * >> >>>>>> > >>> * >> >>>>>> > >>> >> >>>>>> > >>> *SW2#sh run int f0/19 | B inter* >> >>>>>> > >>> >> >>>>>> > >>> interface FastEthernet0/19 >> >>>>>> > >>> >> >>>>>> > >>> switchport trunk encapsulation dot1q >> >>>>>> > >>> >> >>>>>> > >>> switchport mode trunk >> >>>>>> > >>> >> >>>>>> > >>> end >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> *NOTE: The trunk is UP* >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> *SW1#Show int trunk* >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> Port Mode Encapsulation Status Native >> >>>>>> vlan >> >>>>>> > >>> >> >>>>>> > >>> Fa0/19 on 802.1q trunking 10 >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> Port Vlans allowed on trunk >> >>>>>> > >>> >> >>>>>> > >>> Fa0/19 1-4094 >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> Port Vlans allowed and active in management domain >> >>>>>> > >>> >> >>>>>> > >>> Fa0/19 1,10,80 >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> Port Vlans in spanning tree forwarding state and not >> >>>>>> pruned >> >>>>>> > >>> >> >>>>>> > >>> Fa0/19 1,10,80 >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> *SW2#sh spanning-tree blockedports * >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> Name Blocked Interfaces List >> >>>>>> > >>> >> >>>>>> > >>> -------------------- ------------------------------------ >> >>>>>> > >>> >> >>>>>> > >>> VLAN0001 Fa0/19 >> >>>>>> > >>> >> >>>>>> > >>> VLAN0010 Fa0/19 >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> Number of blocked ports (segments) in the system : 2 >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> *All Traffic is blocked for the two Vlans.* >> >>>>>> > >>> >> >>>>>> > >>> *And sure you can get around it, and one way to do this is to >> >>>>>> filter >> >>>>>> > >> BPDUs >> >>>>>> > >>> that carry the VLANs as you mentioned:* >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> SW1(config)#int f0/19 >> >>>>>> > >>> >> >>>>>> > >>> SW1(config-if)#spanning-tree bpdufilter en >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> *SW1#sh spannin blockedports * >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> Name Blocked Interfaces List >> >>>>>> > >>> >> >>>>>> > >>> -------------------- ------------------------------------ >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> Number of blocked ports (segments) in the system : 0 >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> *And I am sure there are other ways. But remember this is the >> >>>>>> default >> >>>>>> > >>> behavior BUT not on all IOSes, on some IOSes, it will >> complain >> >>>>>> that >> >>>>>> > there >> >>>>>> > >>> is a Native VLAN mismatch, but it will NOT block the VLANs >> >>>>>> configured >> >>>>>> > as >> >>>>>> > >>> Native* >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> On Thu, Dec 8, 2011 at 10:35 AM, Narbik Kocharians < >> >>>>>> [email protected] >> >>>>>> > >>> wrote: >> >>>>>> > >>> >> >>>>>> > >>>> Yes, you are correct, you can get around it, i was referring >> >>>>>> to the >> >>>>>> > >>>> default behavior. >> >>>>>> > >>>> >> >>>>>> > >>>> >> >>>>>> > >>>> On Thu, Dec 8, 2011 at 9:23 AM, Paul Cocker < >> >>>>>> [email protected]> >> >>>>>> > >> wrote: >> >>>>>> > >>>> >> >>>>>> > >>>>> Spanning-tree... >> >>>>>> > >>>>> >> >>>>>> > >>>>> I'm guessing the vlan is in the bpdu. >> >>>>>> > >>>>> >> >>>>>> > >>>>> with this config... >> >>>>>> > >>>>> >> >>>>>> > >>>>> SW1 >> >>>>>> > >>>>> interface FastEthernet0/13 >> >>>>>> > >>>>> switchport trunk encapsulation dot1q >> >>>>>> > >>>>> switchport trunk native vlan 10 >> >>>>>> > >>>>> switchport mode trunk >> >>>>>> > >>>>> switchport nonegotiate >> >>>>>> > >>>>> >> >>>>>> > >>>>> SW2 >> >>>>>> > >>>>> interface FastEthernet0/13 >> >>>>>> > >>>>> switchport access vlan 20 >> >>>>>> > >>>>> switchport trunk encapsulation dot1q >> >>>>>> > >>>>> switchport trunk native vlan 20 >> >>>>>> > >>>>> switchport mode trunk >> >>>>>> > >>>>> switchport nonegotiate >> >>>>>> > >>>>> no cdp enable >> >>>>>> > >>>>> >> >>>>>> > >>>>> >> >>>>>> > >>>>> you get this... >> >>>>>> > >>>>> >> >>>>>> > >>>>> *Mar 1 00:18:26.994: %SPANTREE-2-RECV_PVID_ERR: Received >> >>>>>> BPDU with >> >>>>>> > >>>>> inconsistent peer vlan id 10 on FastEthernet0/13 VLAN20. >> >>>>>> > >>>>> *Mar 1 00:18:26.994: %SPANTREE-2-BLOCK_PVID_LOCAL: >> Blocking >> >>>>>> > >>>>> FastEthernet0/13 on VLAN0020. Inconsistent local vlan. >> >>>>>> > >>>>> >> >>>>>> > >>>>> You can disable spanning tree, or use bpdufilter to get >> >>>>>> around it. >> >>>>>> > >>>>> >> >>>>>> > >>>>> >> >>>>>> > >>>>> On 08/12/2011 16:58, Carlos G Mendioroz wrote: >> >>>>>> > >>>>> >> >>>>>> > >>>>>> What mechanism is responsible for such blocking ? >> >>>>>> > >>>>>> >> >>>>>> > >>>>>> -Carlos >> >>>>>> > >>>>>> >> >>>>>> > >>>>>> Narbik Kocharians @ 08/12/2011 13:34 -0300 dixit: >> >>>>>> > >>>>>> >> >>>>>> > >>>>>>> Between any two switch if the Native VLAN is mismatched >> the >> >>>>>> trunk >> >>>>>> > >> will >> >>>>>> > >>>>>>> come up but you won't be able to pass any traffic through >> >>>>>> it, and >> >>>>>> > you >> >>>>>> > >>> can >> >>>>>> > >>>>>>> see that with a "Show spanning block". >> >>>>>> > >>>>>>> On Thu, Dec 8, 2011 at 4:31 AM, David Bass >> >>>>>> > >>> <[email protected]<mailto: >> >>>>>> > >>>>>>> [email protected]**>> wrote: >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> We are talking about CCIE lab, so best practice and >> >>>>>> "working" >> >>>>>> > >> status >> >>>>>> > >>>>>>> all go out the window :). In his scenario he's talking >> >>>>>> about >> >>>>>> > >> router >> >>>>>> > >>>>>>> to switch trunk, so no VTP or STP (if you do this switch >> >>>>>> to switch >> >>>>>> > >>>>>>> you'll definitely have issues though, so very good to >> >>>>>> know)...CDP >> >>>>>> > >>>>>>> will definitely bark non-stop though which is very >> >>>>>> irritating. >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> On Dec 8, 2011, at 6:08 AM, Carlos G Mendioroz wrote: >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>>> May be depending on the equipment, the trunk will "form" >> >>>>>> just >> >>>>>> > fine, >> >>>>>> > >>>>>>>> if VLAN hopping is not considered to be a problem :) >> >>>>>> > >>>>>>>> CDP may barf. If VLAN 1 is involved, other griefs will >> pop. >> >>>>>> > >>>>>>>> >> >>>>>> > >>>>>>>> Different problems: >> >>>>>> > >>>>>>>> -framing: no problem, but "native VLAN" frames do not >> >>>>>> signal >> >>>>>> > >>>>>>> which VLAN >> >>>>>> > >>>>>>>> they belong to, so if they do not match, frames will hop >> >>>>>> from one >> >>>>>> > >>>>>>> VLAN >> >>>>>> > >>>>>>>> to the other. >> >>>>>> > >>>>>>>> >> >>>>>> > >>>>>>>> -signalling (DTP): AFAIK, VLANs are not part of the info >> >>>>>> > >>>>>>> interchanged, so the trunk will form even if native is >> not >> >>>>>> the >> >>>>>> > >> same. >> >>>>>> > >>>>>>>> >> >>>>>> > >>>>>>>> -control: (CDP/VTP/STP/...): well, you may have a >> problem >> >>>>>> here. >> >>>>>> > >>>>>>>> In particular, CDP/VTP go on VLAN 1, so if this is one >> of >> >>>>>> the >> >>>>>> > VLANs >> >>>>>> > >>>>>>>> involved in the crossing, it won't work. >> >>>>>> > >>>>>>>> >> >>>>>> > >>>>>>>> -Others ? >> >>>>>> > >>>>>>>> >> >>>>>> > >>>>>>>> -Carlos >> >>>>>> > >>>>>>>> >> >>>>>> > >>>>>>>> >> >>>>>> > >>>>>>>> David Bass @ 08/12/2011 08:25 -0300 dixit: >> >>>>>> > >>>>>>>>> The trunk will come up fine, but you won't have IP >> >>>>>> connectivity >> >>>>>> > >>>>>>> between the 2 devices on the VLANs/subnets you are >> >>>>>> expecting >> >>>>>> > >> because >> >>>>>> > >>>>>>> the 2 native VLANs are being bridged. Do some research >> on >> >>>>>> how >> >>>>>> > >> dot1q >> >>>>>> > >>>>>>> trunks work and you should be able to figure it out. On >> >>>>>> Dec 7, >> >>>>>> > >> 2011, >> >>>>>> > >>>>>>> at 11:40 PM, CCIE KID <[email protected] >> >>>>>> > >>>>>>> <mailto:[email protected]>> wrote: >> >>>>>> > >>>>>>>>>> Hi fellas, >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> I tested a scenario where the Native vlan differs from >> >>>>>> the >> >>>>>> > >>>>>>> router port to >> >>>>>> > >>>>>>>>>> the switch port. I understood that if the NAtive vlan >> >>>>>> > >>>>>>> mismatches on a trunk >> >>>>>> > >>>>>>>>>> port , then appropriate trunking wont be formed. >> >>>>>> > >>>>>>>>>> But when i connect my router to a switch and in the >> >>>>>> router >> >>>>>> > >>>>>>> subinterface . I >> >>>>>> > >>>>>>>>>> am having a native vlan of 20 and in the switch port >> it >> >>>>>> is >> >>>>>> > >>>>>>> having a native >> >>>>>> > >>>>>>>>>> vlan of 10 , but still the trunk is forming perfectly >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> Can someone correct me >> >>>>>> > >>>>>>>>>> fa0/1.1 fa0/1 >> >>>>>> > >>>>>>>>>> >> >>>>>> Router1-----------------------**------------------------Switch 1 >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> Router 1 >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> inter fa 0/1.1 >> >>>>>> > >>>>>>>>>> encap dot1q 20 native >> >>>>>> > >>>>>>>>>> ip add 10.1.1.1 255.255.255.0 >> >>>>>> > >>>>>>>>>> no sh >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> Switch 1 >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> int fa 0/1 >> >>>>>> > >>>>>>>>>> enc dot1q 10 native >> >>>>>> > >>>>>>>>>> swi trunk enc dot >> >>>>>> > >>>>>>>>>> swi mo trunk >> >>>>>> > >>>>>>>>>> no sh >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> But s >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> -- >> >>>>>> > >>>>>>>>>> With Warmest Regards, >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> CCIE KID >> >>>>>> > >>>>>>>>>> CCIE#29992 (Security) >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> Blogs and organic groups at http://www.ccie.net >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> ______________________________**______________________________** >> >>>>>> > >>>>>>> ___________ >> >>>>>> > >>>>>>>>>> Subscription information may be found at: >> >>>>>> > >>>>>>> >> >>>>>> > >>> http://www.groupstudy.com/**list/CCIELab.html< >> >>>>>> > >> http://www.groupstudy.com/list/ >> >>>>>> > >>> CCIELab.html> >> >>>>>> > >>>>>>>>> Blogs and organic groups at http://www.ccie.net >> >>>>>> > >>>>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> ______________________________**______________________________** >> >>>>>> > >>>>>>> ___________ >> >>>>>> > >>>>>>>>> Subscription information may be found at: >> >>>>>> > >>>>>>> >> >>>>>> > >>> http://www.groupstudy.com/**list/CCIELab.html< >> >>>>>> > >> http://www.groupstudy.com/list/ >> >>>>>> > >>> CCIELab.html> >> >>>>>> > >>>>>>>> >> >>>>>> > >>>>>>>> -- >> >>>>>> > >>>>>>>> Carlos G Mendioroz <[email protected] <mailto: >> >>>>>> [email protected]>> >> >>>>>> > >>>>>>> LW7 EQI Argentina >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> Blogs and organic groups at http://www.ccie.net >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> ______________________________**______________________________** >> >>>>>> > >>>>>>> ___________ >> >>>>>> > >>>>>>> Subscription information may be found at: >> >>>>>> > >>>>>>> >> >>>>>> > >>> http://www.groupstudy.com/**list/CCIELab.html< >> >>>>>> > >> http://www.groupstudy.com/list/ >> >>>>>> > >>> CCIELab.html> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>>> -- >> >>>>>> > >>>>>>> *Narbik Kocharians >> >>>>>> > >>>>>>> *CCSI#30832, CCIE# 12410 (R&S, SP, Security) >> >>>>>> > >>>>>>> *www.MicronicsTraining.com* >> >>>>>> > >>> <http://www.micronicstraining.**com/< >> >>>>>> http://www.micronicstraining.com/ >> >>>>>> > > >> >>>>>> > >>>>>>>> >> >>>>>> > >>>>>>> Sr. Technical Instructor >> >>>>>> > >>>>>>> YES! We take Cisco Learning Credits! >> >>>>>> > >>>>>>> Training & Remote Racks available >> >>>>>> > >>>>>>> >> >>>>>> > >>>>>> >> >>>>>> > >>>>> >> >>>>>> > >>>>> Blogs and organic groups at http://www.ccie.net >> >>>>>> > >>>>> >> >>>>>> > >>>>> >> >>>>>> ______________________________**______________________________** >> >>>>>> > >>>>> ___________ >> >>>>>> > >>>>> Subscription information may be found at: >> >>>>>> > http://www.groupstudy.com/** >> >>>>>> > >>>>> list/CCIELab.html < >> >>>>>> http://www.groupstudy.com/list/CCIELab.html> >> >>>>>> > >>>>> >> >>>>>> > >>>>> >> >>>>>> > >>>>> >> >>>>>> > >>>>> >> >>>>>> > >>>>> >> >>>>>> > >>>>> >> >>>>>> > >>>>> >> >>>>>> > >>>>> >> >>>>>> > >>>> >> >>>>>> > >>>> >> >>>>>> > >>>> -- >> >>>>>> > >>>> *Narbik Kocharians >> >>>>>> > >>>> * >> >>>>>> > >>>> CCSI#30832, CCIE# 12410 (R&S, SP, Security) >> >>>>>> > >>>> *www.MicronicsTraining.com* < >> http://www.micronicstraining.com/ >> >>>>>> > >> >>>>>> > >>>> Sr. Technical Instructor >> >>>>>> > >>>> YES! We take Cisco Learning Credits! >> >>>>>> > >>>> Training & Remote Racks available >> >>>>>> > >>>> >> >>>>>> > >>>> >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> -- >> >>>>>> > >>> *Narbik Kocharians >> >>>>>> > >>> *CCSI#30832, CCIE# 12410 (R&S, SP, Security) >> >>>>>> > >>> *www.MicronicsTraining.com* < >> http://www.micronicstraining.com/> >> >>>>>> > >>> Sr. Technical Instructor >> >>>>>> > >>> YES! We take Cisco Learning Credits! >> >>>>>> > >>> Training & Remote Racks available >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> > >>> Blogs and organic groups at http://www.ccie.net >> >>>>>> > >>> >> >>>>>> > >>> >> >>>>>> >> _______________________________________________________________________ >> >>>>>> > >>> Subscription information may be found at: >> >>>>>> > >>> http://www.groupstudy.com/list/CCIELab.html >> >>>>>> > >> >> >>>>>> > >> >> >>>>>> > >> Blogs and organic groups at http://www.ccie.net >> >>>>>> > >> >> >>>>>> > >> >> >>>>>> >> _______________________________________________________________________ >> >>>>>> > >> Subscription information may be found at: >> >>>>>> > >> http://www.groupstudy.com/list/CCIELab.html >> >>>>>> > >> >> >>>>>> > >> >> >>>>>> > >> >> >>>>>> > >> >> >>>>>> > >> >> >>>>>> > >> >> >>>>>> > >> >> >>>>>> > >> >> >>>>>> > > >> >>>>>> > > >> >>>>>> > > -- >> >>>>>> > > With Warmest Regards, >> >>>>>> > > >> >>>>>> > > CCIE KID >> >>>>>> > > CCIE#29992 (Security) >> >>>>>> > > >> >>>>>> > > >> >>>>>> > > Blogs and organic groups at http://www.ccie.net >> >>>>>> > > >> >>>>>> > > >> >>>>>> >> _______________________________________________________________________ >> >>>>>> > > Subscription information may be found at: >> >>>>>> > > http://www.groupstudy.com/list/CCIELab.html >> >>>>>> > >> >>>>>> > >> >>>>>> > Blogs and organic groups at http://www.ccie.net >> >>>>>> > >> >>>>>> > >> >>>>>> >> _______________________________________________________________________ >> >>>>>> > Subscription information may be found at: >> >>>>>> > http://www.groupstudy.com/list/CCIELab.html >> >>>>>> >> >>>>>> >> >>>>>> Blogs and organic groups at http://www.ccie.net >> >>>>>> >> >>>>>> >> >>>>>> >> _______________________________________________________________________ >> >>>>>> Subscription information may be found at: >> >>>>>> http://www.groupstudy.com/list/CCIELab.html >> >>>>>> >> >>>>>> >> >>>>>> >> >>>>>> >> >>>>>> >> >>>>>> >> >>>>>> >> >>>>>> >> >>>>> >> >>>>> >> >>>>> -- >> >>>>> -- >> >>>>> Olugbenga Oyebande >> >>>>> MD, DAIT >> >>>>> 234-803-302-5287 >> >>>>> http://www.dait-ng.com >> >>>>> Cisco Unified Network, VPN >> >>>>> DAIT Enterprise Network Servers >> >>>>> Broadband Internet Deployment & ISP Consultancy >> >>>>> >> >>>>> >> >>>> >> >>> >> >>> >> >>> -- >> >>> -- >> >>> Olugbenga Oyebande >> >>> MD, DAIT >> >>> 234-803-302-5287 >> >>> http://www.dait-ng.com >> >>> Cisco Unified Network, VPN >> >>> DAIT Enterprise Network Servers >> >>> Broadband Internet Deployment & ISP Consultancy >> >>> >> >>> >> >> >> >> >> >> -- >> >> With Warmest Regards, >> >> >> >> CCIE KID >> >> CCIE#29992 (Security) >> >> >> >> >> >> >> > >> >> >> -- >> With Warmest Regards, >> >> CCIE KID >> CCIE#29992 (Security) >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, please >> visit www.ipexpert.com >> >> Are you a CCNP or CCIE and looking for a job? Check out >> www.PlatinumPlacement.com >> >> http://onlinestudylist.com/mailman/listinfo/ccie_rs >> > > -- With Warmest Regards, CCIE KID CCIE#29992 (Security) _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
