57 th IETF VIENNA draft-sheng-ppvpn-isis-bgp-mpls vpn-01.txt PPVPN @ 57 th IETF meeting IS-IS as the...

57th IETF VIENNA draft-sheng-ppvpn-isis-bgp-mpls vpn-01.txt

PPVPN @ 57th IETF meeting

IS-IS as the PE/CE Protocol

in BGP/MPLS VPNdraft-sheng-ppvpn-isis-bgp-mpls-00.txt

[email protected][email protected]

[email protected] [email protected]

Slide 1


Motivation

In 2547 VPN, PE-CE routing protocol can be EBGP,OSPF,RIP,Static routing etc,IS-IS can also assume this function.

In OSPF case ,there are draft-rosen and draft-ishiguro addressing the problem.

In IS-IS case,no such draft,this draft will fill the vacancy.

Slide 2


When IS-IS is already used in customer network.

CEs need only run one routing protocol. Little impact on transition from legacy customer network.

A new choice for CE-PE routing protocol.

Benefits

Slide 3


Fundamental Model Assumptions

No back door IS-IS link between CEs in the same VPN.

Multiple IS-IS instances(Applicable to Extended Model)

Support Multiple IS-IS instances in one PE Each instance bound to one specific VRF.

IS-IS interaction with BGP on PE PEs have the capability to import IS-IS and BGP routes to/from

each other in particular VRFs. Import BGP routes to IS-IS as external routes,TLV 130. Narrow IS-IS metric style:0-1023, Wide IS-IS metric style:0-4261412864(2^32-2^25),TLV 135

Contents(1/5)

Slide 4


Extended Model Support back door IS-IS link between CEs of

the same VPN.

Contents(2/5)

Slide 5


Contents(3/5) Extended Model

Carry IS-IS information with BGP Extended communities (first two bytes)

IS-IS Route Type Extended Communites Attribute.• Level type (bit 1/byte 3rd,0/1:level 1/2)• Metric style type (bit 2/byte 3rd,0/1:narrow/wide)• TLV Reachability type (0/1:internal/external)• Metric type (0/1: internal metric/external metric)• Sham-link endpoint address (1:sham link end)

IS-IS System ID Extended Communites Attribute MED.The value of the IS-IS distance associated with the route, plus 1.

Slide 6



Route loop prevention on PEs PE1 and PE2 both import BGP routes into their attached CE sites, the route loop maybe happen. To avoid the route loop, it is assumed here that both PE1 and PE2 act as L1/2 router and there exists level-1 adjacency between each PE-CE link. Refer to RFC 2966 to avoid route loop (use up/down bit).

IS-IS interaction with BGP on PE When Egress PE receives a VPN-IP routes, converts them back to IS-IS. The creation of IS-IS LSP bases on IS-IS route original information carried by BGP extended communities

Slide 7



Sham-link Creation Each end PE assigns an shamlink endpoint address. BGP imports direct route designated as source shamlink endpoint address on PE2. Converted BGP route carries BGP extended communities (sham-link endpoint address bit set,IS-IS System ID Extended Communites Attribute equal to the System ID of the IS-IS instance on the PE2. PE1 receives the route, gets the IS-IS System ID in BGP route, checks the sham-link endpoint address bit, create shamlink or not. PE1 adds Neighbor reachability TLV in its self-originated LSP and floods it to CE1. Similar process will happen on PE2.When PE finds that the system ID of the other end of the sham-link is changed, flushes the old LSP and generates new LSP according to the new system ID got from BGP route.

Slide 8


Next Step

Please review the draft Comments are welcome Discussion and revision Can it progress to WG draft?

Slide 9

57 th IETF VIENNA draft-sheng-ppvpn-isis-bgp-mpls vpn-01.txt PPVPN @ 57 th IETF meeting IS-IS as the...

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